Random Mix of Questions

Question 1

How does the micturition reflex prevent urination?

Answer 1

Higher control centers in the brain can inhibit the reflex by inhibiting the descending inputs that control the reflex from being expressed. (Parasympathetic neurons and somatic motor neurons)

Question 2

Name the epithelial segments of the kidney:

Answer 2

Bowman’s capsule->Proximal Tubule->Loop of Henle->Distal tubule->Collecting ducts

Question 3

Name the vascular segments of the kidney:

Answer 3

Afferent arteriole-> Efferent arteriole-> Peritubular capillaries

Question 4

What vascular segments create the filtrant?

a. Afferent arteriole
b. Efferent arteriole
c. Peritubular capillaries

Answer 4

Afferent and Efferent arterioles

Question 5

What vascular segment is responsible for reabsorption?

a. Afferent arteriole
b. Efferent arteriole
c. Peritubular capillaries

Answer 5

Peritubular capillaries

Question 6

How much of the Cardiac Output is diverted to the kidneys?

a. 5L/min
b. 3L/min
c. 500 mL/min
d. 1 L/min

Answer 6

d. 1 L/min - which is 1/5 of the CO (5L)

Question 7

What is in the filtrate?

a. red blood cells
b. plasma
c. electrolytes
d. plasma proteins
e. toxins
f. everything except red blood cells

Answer 7

f. everything except red blood cells

Question 8

What are the 3 processes of the kidneys?

a. filtration
b. reabsorption
c. secretion
d. degradation
e. a, b, c

Answer 8

e. a, b, c

Question 9

What are the steps the plasma must go through to enter Bowman’s capsule?

Answer 9

Plasma must:
1. Cross the endothelial cells (“fenistrated gaps” that are large enough for glucose, water and electrolytes to flow through. They have a negative charge).
2. Cross the epithelial cells (Podicytes) that have a negative charge
3. Fill the Bowman’s capsule
(negatively charged ions like Cl and large plasma proteins are repelled unless there is a state of inflammation which makes the “gaps” bigger and these can pass through)

Question 10

The presence of proteins in the urine indicates what may be happening?

a. Protein intake is too high
b. Muscle wasting
c. Filtration barrier is breaking down
d. Filtration barrier is becoming more selective

Answer 10

c. Filtration barrier is breaking down

Question 11

What lab value tells you how well the kidneys are doing at removing metabolic byproducts?

a. AST/ALT
b. Albumin
c. Hematocrit
d. BUN

Answer 11

d. BUN

Question 12

A teenage boy is trying to control an asthma attack and inhales a beta-adrenergic agonist. The cardiovascular effect of this drug would be to:

a. decrease venous return
b. decrease heart rate
c. decrease peripheral resistance
d. decrease the height of the atrial wave
e. decrease the initial blood pressure reduction that occurs on standing

Answer 12

c. decrease peripheral resistance

Beta- adrenergic receptors relax the vascular smooth muscle, so peripheral resistance would decrease, and more blood would flow back to heart.

Question 13

A man with prostate hypertrophy complains of difficulty in emptying the bladder, although pressing on him stomach during urination helps. Another aid to bladder emptying would be to:

a. increase the action of muscarinic receptors on the detrusor muscle
b. decrease adrenergic tone in the detrusor muscle
c. decrease the synthesis of nitric oxide in the corpus cavernous
d. block prostaglandin synthesis
e. block beta-adrenergic action on the internal sphincter of the bladder

Answer 13

a. increase the action of muscarinic receptors on the detrusor muscle

Stimulation of the parasympathetic nerves and subsequent activation of muscarinic receptors on the detrusor smooth muscle would cause bladder contraction.

Question 14

A mother brings her 9 year old boy to the emergency department. He is having difficulty getting air into and out of his lungs. He wheezes, he strains his neck muscles, and he looks cyanotic. What statement is true about him?

a. He is contracting his neck muscles to force air out through his constricted bronchioles
b. part of his breathing difficulty is due to collapses of his small airways during expiration
c. His functional residual capacity has increased
d. His pulmonary blood pressure will decrease
e. His FEV1 has increased

Answer 14

c. His functional residual capacity has increased

The amount of air remaining in the lungs after quiet, unforced exhalation would increase during an asthma episode because the constricted bronchioles impede outflow.

Question 15

An obese woman with hypertension complains of getting tired and out of breath after walking half a block. Lying down to rest does not alleviate her symptoms as well as resting in a sitting position. What statement about her breathing is true?

a. Slow, deep breathing would decrease the work of breathing for her
b. Her obesity is compressing her bronchioles
c. She has respiratory acidosis
d. The work of expanding her rib cage is increased because of her obesity
e. She needs a lower intrathoracic pressure than normal to move air into her lungs

Answer 15

d.The work of expanding her rib cage is increased because of her obesity

To lift her ribs up and out during inspiration, she has to lift the ribs and the heavy fat layers on top of them. A supine or prone position makes expanding the lungs even more difficult because the effect of gravity in pulling the diaphragm and abdominal contents downward is lost.

Question 16

An escaped convict is shot by police while fleeing through the woods and being tracked down by bloodhounds. The bullet severes his left femoral artery, and he loses 2 L of blood before being transported to the hospital and stabilized. What statement would be true about his condition when he arrives at the hospital?

a. His Po2 would be decreased
b. Respiratory alkalosis would occur
c. Blood potassium levels would decrease
d. His glomerular filtration rate would be decreased
e. Albuminuria would occur

Answer 16

d. His glomerular filtration rate would be decreased

The loss of blood would decrease his blood pressure and cause sympathetically mediated constriction of his afferent glomerular arterioles. The reduced blood pressure and the constriction of his afferent arterioles would lessen blood flow through the glomeruli and decrease the glomerular filtration rate.

Question 17

A woman has untreated diabetes mellitus and a high concentration of unreabsorbed glucose in her urine. This high urinary glucose would:

a. Increase urine volume
b. Increase sodium reabsorption
c. Increase urinary concentrating ability
d. Decrease inulin clearance
e. Alkalinize the urine

Answer 17

a. Increase urine volume

Unreabsorbed glucose would cause an osmotic diuresis.

Question 18

A 60-year-old female alcoholic with cirrhosis has developed ascites. This abdominal fluid accumulation is due to:

a. Closure of lymphatic aquaporin channels resulting from the buildup of toxins no longer able to be metabolized by the diseased liver
b. Decreased plasma oncotic pressure in the capillaries
c. Increased hydrostatic pressure in the lymph ducts
d. A decreased supply of clotting factors
e. Increased extracellular fluid osmolality

Answer 18

b. Decreased plasma oncotic pressure in the capillaries

Because the cirrhotic liver does not synthesize sufficient albumin and other plasma proteins, the plasma oncotic pressure is low, allowing the plasma hydrostatic pressure (because it is less opposed by the plasma oncotic pressure) to drive fluid into the interstitium to produce the ascites.

Question 19

An illegal immigrant crosses the Mexican border and is picked up by the border guards in the Arizona desert, where he has been walking lost, without food or water, for 2 days. The extreme heat and lack of water would:

a. Decrease aldosterone release from the adrenals
b. Cause constriction of the efferent glomerular arteries
c. Cause the release of atrial natriuretic factor
d. Decrease plasma sodium concentrations
e. Decrease the extracellular volume

Answer 19

e. Decrease the extracellular volume

Sodium is the predominant anion in the extracellular compartment, and loss of salt and water, from sweating and in the urine, would cause this compartment to shrink.

Question 20

A 42-year-old woman ruptures her spleen during a skiing accident and has lost 2 L of blood into her abdominal cavity by the time she reaches the hospital. As a result of this blood loss, she would:

a. Have decreased viscosity in the blood remaining in her cardiovascular system
b. Have decreased plasma oncotic pressure
c. Become hyponatremic
d. Have an increased atrial Po2 − venous Po2 gradient
e. Have decreased plasma osmolarity

Answer 20

d. Have an increased atrial Po2 − venous Po2 gradient

Because her blood volume has decreased, she would extract more oxygen from the remaining blood as it passed through the capillary bed.

Question 21

A 2-year-old girl is brought to the nephrology clinic because a urinalysis has found protein in her urine. She is diagnosed as having minimal change disease, a condition in which the glomerulus has become permeable to large molecules, such as plasma proteins. In addition to having albuminuria, this child might have:

a. Anemia because the kidney would stop producing erythropoietin
b. Metabolic acidosis from loss of bicarbonate in the urine
c. Edema because of reduced plasma oncotic pressure
d. A decrease in glucose resorption
e. A decreased glomerular filtration rate

Answer 21

c. Edema because of reduced plasma oncotic pressure

Urinary loss of albumin would decrease plasma oncotic pressure. This loss, by reducing the concentration of osmotically active particles in plasma relative to that in the interstitial fluid, would drive fluid into the interstitial space and produce edema.

Question 22

A student in a Japanese restaurant ate sushi made using raw pufferfish containing tetrodotoxin, a poison that irreversibly blocks fast sodium channels. What would happen as a result of the sodium channel block?

a. Resting membrane potential would increase
b. The T wave of the electrocardiogram would become smaller
c. Conduction through the atrioventricular node would become slower
d. Neuromuscular transmission might fail
e. Aldosterone secretion would decrease

Answer 22

d.Neuromuscular transmission might fail

The action potential to the neuromuscular synapse is conducted by fast sodium channels. Blockage of these channels would block the conduction of this action potential and block the release of neurotransmitter at the neuromuscular junction.

Question 23

A 28-year-old man, running in the Boston Marathon, weighs himself before and immediately after the marathon and finds that he has lost 3 lb during the race. One physiologic consequence of this weight loss would be:

a. An increase in plasma bicarbonate
b. A decrease in hematocrit
c. A decrease in cardiac output
d. An increase in plasma osmolality
e. A decrease in intraocular pressure

Answer 23

d. An increase in plasma osmolality

The weight loss is caused by the loss of hypotonic fluid through sweating and increased respiratory water loss. Loss of hypotonic fluid would increase plasma osmolality, an increase partly, but not completely, compensated for by a shift of water out of the cells and into the extracellular fluid.

Question 24

A patient referred for pulmonary function testing purses his lips during exhalation and breathes slowly, but deeply. A blood sample, taken while he is breathing room air, gives the following values: pH 7.35, Paco2 55 mm Hg, Pao2 50 mm Hg, and HCO3− 28 mEq/L. What statement about this patient is true?

a. He has partly compensated metabolic acidosis
b. His central chemoreceptors have become desensitized to plasma carbon dioxide levels
c. Pulmonary artery pressure would be decreased
d. The low oxygen tension would cause increased destruction of red blood cells
e. His residual volume would be decreased

Answer 24

b.His central chemoreceptors have become desensitized to plasma carbon dioxide levels

The central chemoreceptors become desensitized to plasma CO2 levels over time if high CO2 concentrations are present, but the desensitization occurs in an indirect way. CO2 in the cerebrospinal fluid combines with oxygen to form carbonic acid, which dissociates into H+ and HCO3−. HCO3−, the portion of carbonic acid able to cross the blood-brain barrier into the central nervous system, makes the central chemoreceptors insensitive to the high H+ concentrations.

Question 25

A Peace Corps volunteer contracts severe diarrhea from drinking untreated water. What would be expected to occur as a result of the patient’s massive diarrheal fluid loss? a. Fluid loss would be from the extracellular compartment b. Loss of electrolytes would cause cerebral edema c. The patient would become alkalotic d. The glomerular filtration rate would decrease e. The patient would have increased plasma potassium concentrations

Answer 25

d. The glomerular filtration rate would decrease The fluid loss would cause the plasma volume, blood pressure, and glomerular filtration rate to decrease.

Question 26

A woman develops pulmonary fibrosis during her recovery from adult respiratory distress syndrome. This condition would cause: a. An increased inspiratory reserve volume b. Increased dead space c. A decreased FEV1 d. Increased exhaled carbon dioxide e. Rapid, shallow breathing

Answer 26

e. Rapid, shallow breathing Fibrosis “stiffens” the lungs, and excessive force is required to increase their volume during inspiration. Rapid, shallow breathing is most energy-efficient and is used by patients with this disease.

Question 27

An 88-year-old man’s prostate cancer has metastasized to the bone, and erosion of the bone by the cancer has released abnormal amounts of calcium into the blood. This release would: a. Increase parathyroid hormone secretion b. Increase osteoblast activity c. Increase liver metabolism of vitamin D d. Cause decreased absorption of dietary calcium e. Decrease calcitonin release

Answer 27

d. Cause decreased absorption of dietary calcium Hypercalcemia would decrease parathyroid secretion, which would decease calcium absorption.

Question 28

A 15-year-old girl joins the cross-country team in the spring and runs 2 hours a day to improve her performance. She hopes to improve her endurance enough to compete in a regional half-marathon in the fall. How would this training schedule change her cardiovascular system? a. Increase maximal heart rate b. Increase hematocrit c. Increase the number of mitochondria in skeletal smooth muscle d. Increase resting arterial blood pressure e. Decrease the lactate threshold

Answer 28

c. Increase the number of mitochondria in skeletal smooth muscle The number and density of mitochondria in skeletal muscle increase as a result of endurance training, enhancing aerobic capacity.

Question 29

An 80-year-old patient, during a physical examination needed before entering a retirement home, is found to have a blood pressure of 160/80 mm Hg and is told that he has systolic hypertension. His high systolic blood pressure is most probably due to: a. Microvascular disease secondary to poorly controlled diabetes b. Age-related desensitization of baroreceptors c. Age-related loss of compliance of the arteries d. Turbulent flow secondary to atherosclerosis e. Renin release and angiotensin production secondary to renal arterial stenosis

Answer 29

c. Age-related loss of compliance of the arteries As an individual ages, the arterial wall becomes more rigid and requires a larger force to distend it, and systolic pressure increases.

Question 30

A 23-year-old woman, who had a blood clot in her calf vein the day after she gave birth, experiences sudden pain and dyspnea later from a pulmonary embolism originating from this clot. What would be expected to occur as an immediate result of this embolism? a. Her ventilation/perfusion ratio would decrease b. Pulmonary hypertension would occur c. Symptoms of obstructive pulmonary disease would appear d. Dead space would decrease e. Her FEV1 would increase

Answer 30

b. Pulmonary hypertension would occur Pulmonary vascular resistance would increase because with blockage of a portion of the blood vessels, blood must flow through a smaller cross-sectional area. This increase in resistance would increase pulmonary artery pressure.

Question 31

A man with diabetic nephropathy has kidney function so compromised that it is recommended he start dialysis. In this process, blood is passed through a tube made with a semipermeable membrane that has isotonic fluid on the other side. What can be expected with this setup? a. Water would not be excreted into the surrounding fluid unless a pressure gradient is applied across the semipermeable membrane b. Excess thyroid hormone could be removed if thyrotoxicosis were present c. Malignant hypertension can be avoided d. Cholesterol levels can be reduced e. Red blood cells may swell and burst while passing through the dialysis tube

Answer 31

a. Water would not be excreted into the surrounding fluid unless a pressure gradient is applied across the semipermeable membrane Water would have a net transport across the membrane only in the presence of an osmotic gradient or a pressure gradient. Because the surrounding fluid is isotonic, and an osmotic gradient is absent, a pressure gradient would have to be supplied. This is usually done by increasing the hydrostatic pressure of the blood flowing through the tube.

Question 32

A patient with metastatic cancer is given morphine for pain and lactulose, an osmotic laxative, to treat the constipation caused by the opiate. In addition to its laxative effect, lactulose administration could cause: a. A decreased plasma potassium concentration b. Metabolic alkalosis c. Impaired fat absorption d. Increased secretion of antidiuretic hormone e. Irritate the bowel wall and increase its permeability to plasma proteins

Answer 32

d. Increased secretion of antidiuretic hormone Osmotic diarrhea causes free water loss in the diarrhea fluid. Antidiuretic hormone would be secreted to counteract the free water loss in the diarrhea fluid by decreasing free water loss by the kidney.

Question 33

Which of the following statements concerning skeletal muscle fibers is NOT correct? A) Skeletal muscle fibers continue to divide throughout childhood as skeletal muscles grow B) Skeletal muscle fibers begin as undifferentiated cells called myoblasts during fetal development C) Skeletal muscle fibers are multinucleated cells D) Some skeletal muscle fibers may reach lengths of 20cm

Answer 33

A) Skeletal muscle fibers continue to divide throughout childhood as skeletal muscles grow After development, growth of skeletal muscle occurs as a result of hypertrophy of existing muscle cells, not by increasing the number of cells. Satellite cells may produce some new skeletal muscle cells after muscle damage. During fetal development undifferentiated cells called myoblasts fuse to form a multinucleated cell that differentiates into a skeletal muscle fiber. Some fibers may extend for the entire length of a muscle, up to 20cm. Reference: [See p. 252]].

Question 34

Thick filaments are composed of ______, while thin filaments are composed of _______. A) Actin; myosin, tropomyosin, and troponin B) Myosin, Troponin, and troponin; actin C) Tropomyosin and troponin; myosin D) Myosin; actin, tropomyosin, and troponin

Answer 34

D) Myosin; actin, tropomyosin, and troponin Thick filaments are composed of the motor protein myosin. Thin filaments are primarily composed of actin, and they also contain smaller amounts of the regulatory proteins tropomyosin and troponin. Reference: [See p. 253; see also Fig.

Question 35

A cross-bridge is A) The region of overlap between thick and thin filaments recognized as the A band B) The proteins that connect two sarcomeres recognized as the Z line C) The portions of myosin molecules that extend from the surface of the thick filaments toward the thin filaments D) The portion of the actin covered by the tropomyosin

Answer 35

C) The portions of myosin molecules that extend from the surface of the thick filaments toward the thin filaments Tension is generated in muscles when the heads of the myosin molecules (cross-bridges) extend to the thin filaments to develop tension. The A band represents the length of the thick filaments in a sarcomere. The Z lines define the two ends of a sarcomere. Tropomyosin covers the myosin binding sites on the actin. Reference: [See p. 253; see also Figs. 9-6 and 9-7]

Question 36

According to the sliding filament mechanism of skeletal muscle contraction, during contraction A) The thick filaments stay the same size but the thin filaments shorten B) The sarcomeres shorten C) The thin filaments stay the same size but the thick filaments shorten D) Both thick and thin filaments shorten

Answer 36

B) The sarcomeres shorten ATP is important for the dissociation of myosin from actin. It is the binding of a molecule of ATP to the myosin that breaks the link between actin and myosin. This allows the cross bridge cycle to be repeated. Hydrolysis of ATP by Ca++-ATPase in the sarcoplasmic reticulum provides the energy for active transport of Ca++ ions back into the sarcoplasmic reticulum from muscle cytosol. This restores cytosolic Ca++ to pre-release levels, ending the contraction and allowing the muscle fiber to relax. In skeletal muscle, actin does not get phosphorylated. The hydrolysis of ATP by myosin ATPase provides the energy for the myosin cross-bridge to bind actin and execute another cycle of power stroke. Calcium binds to troponin and causes the tropomyosin shift. Reference: [See pp. 255-257; see also Fig. 9-8 and Table 9-1].

Question 37

Which of the following is a "regulatory" muscle protein, not directly involved in the act of contraction? A) Troponin B) Actin C) Tropomyosin D) Troponin and tropomyosin E) Myosin and actin

Answer 37

D) Troponin and tropomyosin Troponin and tropomyosin are the regulatory proteins, regulating the initiation of contraction and relaxation. Troponin is activated by the high levels of intracellular calcium. When activated it causes displacement of tropomyosin from actin, thereby enabling the myosin cross-bridges to bind with actin sites. During relaxation, tropomyosin binds with actin preventing cross-bridge binding. Actin and myosin are the major contractile proteins of the muscle. Reference: [See p. 257; see also Fig. 9-9].

Question 38

Excitation-contraction coupling A) Occurs after cross-bridge cycling B) Is characterized by a graded potential in the plasma membrane of the muscle fiber C) Involves a decrease in the cytosolic calcium concentration D) Describes what happens in a muscle fiber between stimulation by acetylcholine and cross-bridge formation

Answer 38

D) Describes what happens in a muscle fiber between stimulation by acetylcholine and cross-bridge formation Excitation-contraction coupling is the sequence of events that follow stimulation of the motor endplate by acetylcholine. These events include an action potential that spreads across the muscle fiber's plasma membrane and the increase in cytosolic concentration of calcium. Excitation-contraction coupling must occur before cross-bridge cycling can occur. Reference: [See pp. 257-258].

Question 39

The ability of a muscle fiber action potential to cause an increase in cytosolic calcium concentration is dependent upon A) The conduction of action potentials down T-tubules which are in intimate contact with the sarcoplasmic reticulum. B) The presence of the voltage sensitive protein called the ryanodine receptor in the T-tubule membrane C) The calcium channel protein called the dihydropyridine receptor which is located in the sarcoplasmic reticulum membrane D) Ca++-ATPase pumps in the sarcoplasmic reticulum

Answer 39

A) The conduction of action potentials down T-tubules which are in intimate contact with the sarcoplasmic reticulum. As an action potential spreads down a T-tubule, it activates the voltage sensitive dihydropyridine receptor in the cell membrane. When the dihydropyridine receptor interacts with the ryanodine receptor in the sarcoplasmic reticulum, it causes the calcium channel in the ryanodine receptor to open and release calcium into the cytosol. The Ca++-ATPase pumps in the sarcoplasmic reticulum work to return calcium to the sarcoplasmic reticulum, and as such would reduce the cytosolic concentration of calcium. Reference: [See pp. 258-259; see also Figs. 9-11 and 9-12].

Question 40

Which of the following statements about motor neurons and muscle fibers is correct? A) A single muscle fiber may be innervated by multiple motor neurons B) Each motor neuron forms a single junction with a muscle fiber C) A single motor neuron plus the muscle fibers it innervates is called a motor unit D) Skeletal muscle fibers are innervated by neurons of the sympathetic system.

Answer 40

C) A single motor neuron plus the muscle fibers it innervates is called a motor unit A single motor neuron plus all the muscle fibers it innervates is called a motor unit. Motor neurons branch multiple times, and each branch may form a junction with a muscle fiber called a neuromuscular junction. However, each muscle fiber is controlled by a branch from only one motor neuron. Skeletal muscles are innervated by the somatic motor system. Reference: [See p. 260; see also Fig. 9-13].

Question 41

At the neuromuscular junction, A) The release of acetylcholinesterase from the motor neuron causes an EPP in the motor end plate B) Acetylcholinesterase inhibits repolarization of the motor end - plate C) An EPP is a graded potential D) Summation of end-plate potentials is required to trigger an action potential in the muscle membrane

Answer 41

C) An EPP is a graded potential At the neuromuscular junction acetylcholine (ACh) diffuses from the axon terminal to the motor end plate where it binds to nicotinic ACh receptors (AChR). This elicits an excitatory motor end-plate potential (EPP) by allowing sodium ions to enter the muscle from the extracellular fluid in the synaptic cleft. Also, some potassium leaves the muscle cell. The movement of these ions occurs through the channel of the AChR. Acetylcholinesterase (AChE) is located on the motor end-plate and is the enzyme that breaks down ACh by hydrolyzing it. When free ACh falls to low levels due to AChE enzyme action, lack of ACh binding to the receptor closes the ion channels and ion movement through the channel stops. The depolarized end-plate returns to resting potential and is ready to respond to the next round of ACh released in response to the next action potential. Although an EPP is a graded potential and not an action potential, summation of end-plate potentials is not required to trigger an action potential. One EPP is more than enough to depolarize the muscle plasma membrane adjacent to the end plate to its threshold leading to an action potential in the muscle fiber membrane. Reference: [See pp. 260-261; see also Fig. 9-15].

Question 42

Which of the following statements regarding the action of curare at a neuromuscular junction is true? A) Curare is an acetylcholine agonist B) Curare binds to acetylcholine receptors C) Curare inhibits acetylcholinesterase D) Curare inhibits acetylcholine release from motor neuron terminals

Answer 42

B) Curare binds to acetylcholine receptors At the neuromuscular junction curare binds to acetylcholine receptors, preventing ACh from binding. Curare is an acetylcholine antagonist because it does not activate the ACh receptors. ACh has no effect on acetylcholinesterase or on acetylcholine release from presynaptic terminals.

Question 43

A person exposed to a pesticide or nerve gas containing organophosphates might experience all of the following EXCEPT: A) Failure to release acetylcholine at the neuromuscular junction B) Prolonged depolarization of the motor end plate C) Paralysis eventually leading to death D) Inability to break down acetylcholine

Answer 43

A) Failure to release acetylcholine at the neuromuscular junction Organophosphates have no effect on the release of acetylcholine by motor neurons. Organophosphates inhibit acetylcholinesterase thus preventing the breakdown of acetylcholine. The sustained presence of acetylcholine would continue to stimulate receptors on the motor end plate leading to a prolonged depolarization. After a prolonged exposure the acetylcholine receptors eventually become insensitive leading to paralysis. If the paralysis affects the respiratory muscles, death may occur.

Question 44

Which of the following statements concerning types of skeletal-muscle contraction is correct? A) In a concentric contraction, the load equals the tension produced B) In a concentric contraction, the load exceeds the tension produced C) In an eccentric contraction, the tension produced exceeds the load D) Concentric contractions begin as isometric contractions

Answer 44

D) Concentric contractions begin as isometric contractions All contractions begin as isometric contractions. Initially, tension develops and increases in the muscle, but muscle fiber length stays the same (isometric contraction). In a concentric contraction (an isotonic contraction) the muscle shortens, which means that tension exceeds the load. In an eccentric contraction (an isotonic contraction) the muscle lengthens, which means the load exceeds the tension

Question 45

Which of the following statements is NOT correct? A) When a muscle contraction maintains a constant level of maximal tension it is said to be in fused tetanus B) Summation occurs due to the repetitive stimulation of a muscle which maintains a steady increase in cytosolic calcium concentrations that leads to a steady increase in muscle tension C) Unfused tetanus occurs at very low stimulation frequencies such that the muscle is allowed to completely relax between each stimulus D) Tetanus occurs as a result of inhibiting the action of the Ca++-ATPase pump in the sarcoplasmic reticulum

Answer 45

C) Unfused tetanus occurs at very low stimulation frequencies such that the muscle is allowed to completely relax between each stimulus Unfused tetanus occurs at low stimulation frequencies, but relaxation between each stimulus is only partial and is not complete. At higher stimulation frequencies a sustained contraction occurs, and a steady tension is achieved which is called fused tetanus or just tetanus. Summation occurs because with each additional stimulus, tension increases due to the sustained level of calcium in the cytosol. This is not due to the inhibition of the Ca++-ATPase pump in the sarcoplasmic reticulum, but rather due to the continued activation of the ryanodine receptor in the sarcoplasmic reticulum.

Question 46

``` It is known that ATP is the direct source of energy for muscle contraction. If the level of ATP drops due to excessive contraction, which of the following compounds stores ATP and can rapidly produce ATP but in a very limited supply? A) ADP B) Creatine-phosphate C) Glucose D) Glycogen E) Fatty acids ```

Answer 46

B) Creatine-phosphate Creatine-phosphate, which is abundant in the muscle cytoplasm, is an additional reserve of chemical energy for immediate use. Its phosphate group can be transferred to ADP to form the needed ATP. Creatine-phosphate is then replenished during muscle recovery. The amount of ATP available via the creatine-phosphate system is limited by the amount of creatine-phosphate present in the muscle cell. ADP is not a source of ATP energy, although it is needed to generate ATP. Glycogen is a storage form of glucose and although glucose and fatty acids can be oxidized and generate ATP, these events occur during the muscle recovery phase and cannot restore ATP levels rapidly while contraction is occurring.

Question 47

Which of the following comparisons of type I (slow-oxidative) skeletal-muscle fibers and type IIb (fast-glycolytic) skeletal-muscle fibers is correct? A) Type I fibers have fewer mitochondria B) Type I fibers fatigue faster C) Type I fibers store more glycogen D) Type I fibers can generate more tension E) Type I fibers have a smaller diameter.

Answer 47

E) Type I fibers have a smaller diameter. Type I muscle fibers (slow-oxidative) have a smaller diameter when compared to Type IIb glycolytic fibers. Oxidative skeletal muscle fibers have more mitochondria than glycolytic fibers, and they are more resistant to fatigue. Glycolytic muscle fibers (Type IIb) contain more glycogen than do oxidative fibers. Type IIb fast glycolytic fibers can generate more tension because they have a greater total number of thick and thin filaments acting together to generate greater tension and velocity.

Question 48

Muscles in the back have a higher proportion of fast-glycolytic fibers (type IIb) relative to slow oxidative (type I) than do muscles in the arms. A) True B) False

Answer 48

B) False his statement is false. The arms have many fast-glycolytic fibers that are used for rapid, precise movements. Back muscles have few, if any, glycolytic muscle fibers. The back muscle fibers are mainly the slow oxidative type used for sustained contractions. Reference: [See pp. 269-270].

Question 49

Which of the following is involved in the hypertrophy of skeletal muscle fibers following exercise? A) Only an increase in the number of muscle fibers B) Only an increase in the diameter and size of muscle fibers C) Only an increase in the number of muscle filaments per muscle fiber D) An increase in the number of muscle filaments per muscle fiber and the resulting increase in the diameter and size of muscle fibers E) An increase in the number of muscle fibers, an increase in the number of muscle filaments per muscle fiber, and the resulting increase in the diameter and size of muscle fibers

Answer 49

D) An increase in the number of muscle filaments per muscle fiber and the resulting increase in the diameter and size of muscle fibers An increase in the size of the whole muscle that follows exercise and subjecting of the skeletal muscle to a load occurs mainly as a result of an increase in the number of muscle filaments (myosin and actin) resulting in the thickening of the muscle fiber (increased diameter). There is no increase in the number of muscle fibers. Muscle fiber production occurs mainly during early development and formation of the skeletal muscle.

Question 50

``` Which of the following is NOT required in the regulation of contraction in smooth muscle? A) Calcium B) Calmodulin C) Troponin D) Myosin light chain kinase ```

Answer 50

C) Troponin Smooth muscle contraction occurs when cytosolic calcium levels rise. Calcium binds to the regulatory protein, calmodulin, which is similar in structure to troponin. The calcium-calmodulin complex then binds to and activates the enzyme myosin light chain kinase. This kinase phosphorylates the myosin light chains on the globular head of myosin. This phosphorylation activates the myosin allowing cross-bridges to form. Troponin itself plays no role in the regulation of contraction in smooth muscle.

Question 51

Which of the following comparisons of skeletal and smooth muscle contraction is correct? A) Skeletal muscle contraction requires the influx of extracellular Ca++, whereas smooth muscle contraction does not B) Skeletal muscle contraction involves interactions between thick and thin filaments, whereas smooth muscle contraction does not C) Skeletal muscle contraction results from cross-bridge cycling, whereas smooth muscle contraction does not D) Smooth muscle contraction requires release of Ca++ from sarcoplasmic reticulum, whereas skeletal muscle contraction does not E) The site of calcium regulation of skeletal muscle contraction is on the thin filament, whereas in smooth muscle contraction calcium regulation involves the thick filament

Answer 51

E) The site of calcium regulation of skeletal muscle contraction is on the thin filament, whereas in smooth muscle contraction calcium regulation involves the thick filament The site of calcium regulation is very different in the two types of muscle. In skeletal muscle, calcium binds to troponin, a regulatory protein, allowing actin (thin filament) and myosin to interact. In smooth muscle, calcium promotes the phosphorylation of myosin (thick filament), activating the myosin. Contraction of both skeletal muscle and smooth muscle involves the interaction of thin and thick filaments in the cross-bridge cycles. In both muscle types the activity of the cross-bridge cycle is regulated by cytosolic calcium levels, but the source of the increase in cytosolic calcium differs. In skeletal muscle, the calcium that initiates contraction comes from the sarcoplasmic reticulum, whereas in the smooth muscle, calcium also comes from the extracellular fluid.

Question 52

Which of the following comparisons between smooth and skeletal muscle fibers is true? A) Nervous stimulation of smooth muscle is always excitatory, whereas nervous stimulation of skeletal muscle may be excitatory or inhibitory. B) The contractile activity of smooth muscle may be affected by hormones, whereas the contractile activity of skeletal muscle is not C) Smooth muscle may be innervated by both the autonomic system and the somatic motor system, whereas skeletal muscle may be innervated by the somatic motor system only D) In the smooth muscle action potential, depolarization is due to the influx of Na++, whereas in the skeletal muscle action potential, depolarization is due to the influx of Ca++

Answer 52

B) The contractile activity of smooth muscle may be affected by hormones, whereas the contractile activity of skeletal muscle is not Smooth muscle plasma membranes contain receptors for a variety of hormones and neurotransmitters, the binding of which can lead to either membrane excitation or inhibition. In contrast, skeletal muscle fibers receive input from somatic motor nerves only, and it is always excitatory. Smooth muscle may be innervated by both divisions of the autonomic nervous system (i.e. sympathetic and/or parasympathetic), but skeletal muscles can only be innervated by the somatic motor system. In action potentials, the influx of Ca++ depolarizes smooth muscle cells while the influx of Na+ depolarizes skeletal muscle cells.

Question 53

Which of the following statements concerning smooth muscle activation is NOT correct? A) Smooth muscle cells are activated by the autonomic nervous system B) Neurotransmitter is released from swollen regions of neurons called varicosities C) Some neurotransmitters increase smooth muscle contraction, while other neurotransmitters decrease smooth muscle contraction D) Smooth muscles have a very high rate of fatigue

Answer 53

D) Smooth muscles have a very high rate of fatigue Smooth muscles have a slow rate of fatigue. Low ATPase activity generally prevents smooth muscle from running out of ATP. This prevents fatigue and allows smooth muscles to contract for longer periods of time than skeletal muscles. All other statements regarding smooth muscle are true.

Question 54

Which of the following statements concerning cardiac muscle cells is correct? A) Dihydropyridine receptors act as calcium channels in the sarcoplasmic reticulum B) Most of the calcium required for contraction is extracellular calcium that enters the cell through voltage gated calcium channels C) Unlike a twitch in skeletal muscle fibers, a twitch in cardiac muscle fibers only releases enough calcium to expose about 30% of the cross-bridge attachment sites on the actin filaments D) Tetanic contractions are possible in cardiac muscle cells because they have a much shorter absolute refractory period than skeletal muscle cells

Answer 54

C) Unlike a twitch in skeletal muscle fibers, a twitch in cardiac muscle fibers only releases enough calcium to expose about 30% of the cross-bridge attachment sites on the actin filaments A twitch in cardiac muscle fibers only releases enough calcium to expose about 30% of the cross-bridge attachment sites on the actin filaments. By modifying the amount of calcium released into the cytosol, the strength of a cardiac muscle fiber contraction can be varied. Most of the calcium required for contraction is released from the sarcoplasmic reticulum. Modified ryanodine receptors are the calcium channels of the sarcoplasmic reticulum. Cardiac muscle fibers do not experience tetanus due to a long absolute refractory period. The cardiac muscle fiber must relax at least partially before the absolute refractory period is over.

Question 55

Which of the following corresponds to the state of myosin under resting conditions and rigor mortis? a. Myosin + ATP b. Myosin + ADP + Pi c. Actin + Myosin + ADP +Pi d. Actin + Myosin

Answer 55

b. Myosin + ADP + Pi ATP is required to detach myosin from actin.

Question 56

If the transverse tubules of a skeletal muscle are disconnected from the plasma membrane, will action potentials trigger a contraction?

Answer 56

No. The transverse tubules conduct the muscle action potential from the plasma membrane into the interior of the fiber, where it can trigger the release of Ca from the SR. If the transverse tubules were not attached to the plasma membrane, an action potential could not be conducted to the SR and there would be no release of Ca to initiate a contraction.

Question 57

What conditions will produce the maximum tension in a skeletal muscle fiber?

Answer 57

Max tension is produced when: a. the fiber is stimulated by an action potential frequency that is high enough to produce a maximal tetanic tension. b. at its optimum length, where the thick and thin filaments have greatest overlap and create the most cross-bridges.

Question 58

If the blood flow to a skeletal muscle were markedly decreased, which types of motor units would most rapidly undergo a severe reduction in their ability to produce ATP for contraction?

Answer 58

The oxidative motor units, fast and slow, will be affected first by the decrease in blood flow because they depend on blood flow to provide both the fuel -glucose and fatty acids- and the oxygen required to metabolize the fuel. The fast-glycolytic motor units will be affected more slowly because they rely predominantly on internal stores of glycogen which is anaerobically metabolized.

Question 59

In the lab, will an isolated skeletal muscle contract when it is placed in a solution with no calcium ions and stimulated: a) by directly depolarizing its membrane, b) stimulating the nerve to the muscle? What would happen if it were smooth muscle?

Answer 59

In the absence of extracellular Ca, skeletal muscle contracts normally because the Ca required comes from the SR within the fibers. If the motor neuron to the muscle is stimulated in a Ca-free medium- the muscle will NOT contract because the influx of Ca from the ECF is needed to trigger release of ACh to trigger the action potential. Smooth muscle: in a Ca free solution do not contract either way because Ca must enter the cell to cause a contraction or Ca release from SR.

Question 60

An endocrine tumor secretes a hormone that leads to elevation of extracellular fluid Ca concentrations. How might this affect cardiac muscle?

Answer 60

a. Elevation of extracellular Ca would increase the amount of Ca entering the cytosol via L-type Ca channels. b. This creates a greater depolarization and would increase the strength of the contraction via release of more Ca through the ryanodine receptor channels.

Question 61

``` Doubling the radius of an artery would _______ the resistance in that artery by _______. A) Decrease; two B) Decrease; four C) Decrease; sixteen D) Increase; two E) Increase; four ```

Answer 61

C) Decrease; sixteen Resistance = 1/radius4. Therefore, doubling the radius would decrease the resistance by sixteen.

Question 62

``` The valve that separates the left atrium and the left ventricle is called the A) Tricuspid valve B) Bicuspid valve C) Left semilunar valve D) Right semilunar valve ```

Answer 62

B) Bicuspid valve The bicuspid valve separates the left atrium and ventricle. This valve is also called the left atrioventricular (AV) valve. The tricuspid valve separates the right atrium and ventricle. The left semilunar valve is also known as the aortic valve, and it separates the left ventricle and the aorta. The right semilunar valve is also known as the pulmonary valve, and it separates the right ventricle and the pulmonary trunk.

Question 63

``` What part of the conductive system of the heart directly delivers the action potential to the ventricular muscle cells or fibers? A) Purkinje fibers B) Bundles of His C) Gap junctions D) Pacemaker cells E) AV node ```

Answer 63

A) Purkinje fibers The best answer here is the Purkinje fibers. Once the pacemaker cells fire, the excitation reaches the AV node and from there it proceeds down the two branches of the bundle of His (left and right branches) and finally to the Purkinje system of conductive cells (fibers). These cells make contact with cardiac muscle cells of the ventricle and excite them to discharge and contract. Note also that not every cardiac muscle cell is innervated by the Purkinje cells. Cardiac muscle cells have gap junctions, which allow the direct transfer of electrical excitation from one muscle cell to another.

Question 64

``` The action potential in myocardial cells is prolonged compared to skeletal muscle cells due to the presence of _______ in myocardial cells. A) L-type calcium channels B) F-type sodium channels C) T-type calcium channels D) Voltage-gated potassium channels ```

Answer 64

A) L-type calcium channels Long-lasting (L-type) calcium channels in myocardial cells open in response to the initial depolarization of these cells. These channels allow calcium ions to enter the cell from the extracellular fluid. Because these channels remain open longer than other voltage-gated ion channels, they allow the membrane to remain depolarized for a longer period of time. F-type sodium channels and T-type calcium channels are important in the pacemaker cells of the SA node. Voltage-gated potassium channels are responsible for the repolarization phase of the action potential in both myocardial cells and skeletal muscle cells.

Question 65

Which of the following statements regarding the pacemaker activity of the heart is true? A) The pacemaker of the heart is normally in the AV node B) Heart rate is increased when adrenergic receptors on the pacemaker cells are activated C) The pacemaker potential is caused by a spontaneous decrease in membrane permeability to sodium D) F-type sodium channels open at threshold E) T-type calcium channels open at threshold

Answer 65

B) Heart rate is increased when adrenergic receptors on the pacemaker cells are activated The heart rate would be increased when adrenergic receptors on the pacemaker cells are activated. The heart is innervated by both sympathetic and parasympathetic nerve fibers. The sympathetic postganglionic fibers release primarily norepinephrine, which acts on beta-adrenergic receptors. Heart rate will increase when these receptors are activated. The SA node is the normal pacemaker for the heart, not the AV node. The pacemaker potential, or slow depolarization in SA cells, is due to a decrease in potassium efflux, an increase in sodium influx through F-type channels, and a transient increase in calcium influx through T-type channels.

Question 66

The type of ion channel important in the oscillation of spontaneous discharges in pacemaker cells of the SA node is the T-type calcium channel. A) True B) False

Answer 66

A) True This statement is true. T-type calcium channels are very critical for pacemaker cell function. These channels require a low voltage for their activation and allow calcium to enter the cells at a membrane potential below threshold. This influx of calcium brings the cell membrane potential to threshold level. In pacemaker cells an L-type calcium channel opens at threshold resulting in the depolarization phase of the action potential. In cardiac muscle cells, the L-type calcium channel is important in allowing calcium to enter the heart after depolarization and thereby prolonging the repolarization phase and refractory period of the action potential.

Question 67

Tetanic contractions in cardiac muscle do not occur due to the long absolute refractory period. A) True. B) False.

Answer 67

A) True. This statement is true. The long absolute refractory period in cardiac muscle occurs due to the prolonged open time of the L-type calcium channels. Relaxation of the cardiac muscle cell begins before the absolute refractory period has ended. As a result, the cardiac muscle cannot develop tetanus.

Question 68

Which of the following statements regarding the cardiac cycle is true? A) The AV valves are open during most of diastole (mainly ventricular diastole) B) The aortic valve is closed throughout the interval between the QRS and T waves C) The first heart sound is the opening of the AV valves D) The ventricular pressure is greater than the aortic pressure during isovolumetric contraction E) SL valves open when pressure in the ventricles is less than pressure in the great arteries

Answer 68

A) The AV valves are open during most of diastole (mainly ventricular diastole) During the cardiac cycle, AV valves are open during ventricular diastole, and blood is passing from the atria to ventricles through the AV valves. The first heart sound, or lub, is made by the closing of the AV valves, not their opening. Ventricular pressure is less than aortic pressure during isovolumetric contraction, and SL valves are closed. The time between the QRS and T waves is when the ventricle is contracting (ventricular systole) and pushing the blood through the open aortic valve into the aorta.

Question 69

Which of the following statements concerning the period of isovolumetric ventricular contraction is true? A) Pressure in the ventricles is decreasing B) The volume of blood in the ventricles is decreasing C) The ventricles are completely closed chambers D) The blood in the atria is moving into the ventricles

Answer 69

C) The ventricles are completely closed chambers During isovolumetric ventricular contraction, ventricular systole produces an increase in ventricular pressure. This increase in pressure is great enough to close the AV valves, but it is not great enough to open the SL valves. As a result, the ventricles are closed chambers and the volume of blood in them does not change. This period ends when pressure in the ventricle becomes greater than the pressure in the great arteries and the SL valves open and blood begins to leave the ventricles.

Question 70

The majority of ventricular filling occurs while A) Both the atria and ventricles are in systole B) The atria are in diastole and the ventricles are in systole C) Both the atria and ventricles are in diastole D) The atria are in systole and the ventricles are in diastole

Answer 70

C) Both the atria and ventricles are in diastole Approximately 80% of ventricular filling occurs while the heart is completely at rest. This period of passive filling is followed by atrial systole which adds the final 20% of blood to the ventricles (still in diastole) to achieve the end diastolic volume (EDV).

Question 71

The left ventricle ejects a larger volume of blood during systole than does the right ventricle because the left ventricular pressure is greater than the right. A) True B) False

Answer 71

B) False Although during systole the left ventricular pressure is higher than the right ventricular pressure, the two ventricles pump the same volume of blood.

Question 72

Which of the following statements concerning the cardiac output in a resting, average adult human is true? A) It is the amount of blood delivered by one of the heart's ventricles in one hour B) It is approximately 5 liters per min C) It is equal to [HR] X [EDV] D) It is the sum of blood pumped by both left and right ventricles in one minute

Answer 72

B) It is approximately 5 liters per min Since at resting condition, the average heart rate is about 72 beats per minute and since in the average adult person, the stroke volume is about 70 ml, the product of these two values is 5000 ml or 5 liters per minute. Cardiac output is the amount of blood delivered by either of the ventricles in one minute. It is defined by HR (heart rate) X SV (stroke volume). Note that during exercise cardiac output increases markedly to supply blood to the exercising muscles.

Question 73

Which of the following is an appropriate definition of the Frank-Starling mechanism? A) Stroke volume decreases as end-systolic volume increases B) Stroke volume increases as contractility increases C) Stroke volume increases as end-diastolic volume increases D) Stroke volume increases as end-systolic volume decreases

Answer 73

C) Stroke volume increases as end-diastolic volume increases While all of these statements are true, only the following is an accurate definition of the Frank-Starling mechanism. A larger end-diastolic volume leads to an increase in stroke volume. This effect is independent of contractility, yet an increase in contractility also results in an increase in stroke volume. Stroke volume and end-systolic volume are inversely related since EDV-SV = ESV.

Question 74

Which of the following is NOT a result of sympathetic stimulation of the heart? A) Increase in heart rate B) Decrease in contractility C) Increase in calcium entry into the myocardial cells D) Decrease in the length of time required for a cell to contract and relax

Answer 74

B) Decrease in contractility Sympathetic stimulation of the heart leads to an increase in contractility, not a decrease. Sympathetic stimulation of the heart leads to an increase in the slope of the pacemaker potential by increasing the permeability of the F-type Na+ channels. This results in an increase in heart rate. Sympathetic stimulation of the heart leads to an increase in calcium entry into the cells. This increased cytosolic calcium leads to increases in contractility and force of contraction. Sympathetic stimulation also causes the entire process of contraction/relaxation to occur more quickly, thus it decreases the time required for a cell to contract and relax.

Question 75

``` For an average, healthy adult, the normal systolic and diastolic pressure values within the main systemic arteries are _________ and __________ mm Hg respectively. These same values for the left ventricle are ______________ and ______________ mm Hg. A) 120 and 80; 120 and 10 B) 80 and 40; 100 and 80 C) 120 and 80; 120 and 50 D) 80 and 120; 10 and 120 ```

Answer 75

A) 120 and 80; 120 and 10

Question 76

Which of the following statements concerning blood flow is NOT correct? A) Blood flow increases when MAP increases B) Blood flow increases when the radius of the vessel increases C) Blood flow increases when resistance increases D) Blood flow increases when arterioles vasodilate

Answer 76

C) Blood flow increases when resistance increases Blood flow decreases when resistance increases. Blood flow increases when MAP increases, vessel radius increases, and resistance decreases. A decrease in resistance is the direct result of an increase in vessel radius, vasodilation.

Question 77

Because sympathetic stimulation of the arterioles causes vasoconstriction, the sympathetic system plays no role in vasodilation. A) True B) False

Answer 77

B) False The arterioles receive a vast supply of post-ganglionic sympathetic nerve fibers that release norepinephrine. Norepinephrine acts on the alpha adrenergic receptors on smooth muscle to cause vasoconstriction, and there is always at least a basal level of firing by these neurons which is known as sympathetic tone. Dilation of the arterioles can be obtained by decreasing the rate of sympathetic activity below this tonic basal level. In addition, smooth muscles of the skeletal muscle arterioles have beta 2 adrenergic receptors. Stimulation of these receptors due to sympathetic stimulation of the adrenal medulla to secrete epinephrine (adrenaline) results in vasodilation of these arterioles.

Question 78

Net filtration pressure would be increased by A) A decrease in the concentration of plasma proteins B) A decrease in capillary hydrostatic pressure C) A decrease in the concentration of interstitial fluid proteins D) An increase in hydrostatic pressure of the interstitial fluid

Answer 78

A) A decrease in the concentration of plasma proteins Net filtration pressure increases due to an increase in capillary hydrostatic pressure, a decrease in the concentration of plasma proteins, an increase in the concentration of interstitial fluid proteins, or a decrease in the hydrostatic pressure of the interstitial fluid.

Question 79

Which two physiological pumps help to increase venous return of blood to the heart? A) Left and right heart pumps B) Skeletal muscle pump and respiratory pump C) Venous pump and respiratory pump D) Skeletal muscle pump and ventricular pump

Answer 79

B) Skeletal muscle pump and respiratory pump The two physiologic pumps involved in venous return are the skeletal muscle pump and the respiratory pump. The skeletal muscle pump is especially important in leg muscles and particularly during walking activity. The veins, which are located between the large leg skeletal muscles, are squeezed during the contractions of these muscles, and this pushes the blood in the veins toward the heart. The one-way valves of the veins do not allow back flow of blood. The skeletal muscle pump is not very effective during sleep and resting conditions when body is in the supine position. The respiratory pump is effective during the inspiratory phase of breathing. Inspiration increases chest volume and decreases pressure within the chest cavity, which in turn aids in venous blood flow towards the heart. You can imagine that inspiration acts like a vacuum pump, sucking the blood towards the chest cavity.

Question 80

mmediately after a hemorrhage, baroreceptors _________ their firing rate, signaling the medullary cardiovascular center to __________ the activity of the sympathetic nerves to the heart, arterioles and veins. The result of this reflex would be to increase the __________ and ____________ to above normal levels and to bring the ___________,____________ and ____________back toward pre-hemorrhage values. A) Increase; increase; stroke volume and peripheral resistance; heart rate, cardiac output and arterial blood pressure. B) Decrease; increase; heart rate and peripheral resistance; stroke volume, cardiac output and arterial blood pressure. C) Increase; decrease; heart rate and peripheral resistance; stroke volume, cardiac output and arterial blood pressure. D) Decrease; increase; heart rate and arterial blood pressure; peripheral resistance, stroke volume and cardiac output. E) Decrease; decrease; heart rate and cardiac output; stroke volume, peripheral resistance and arterial blood pressure.

Answer 80

B) Decrease; increase; heart rate and peripheral resistance; stroke volume, cardiac output and arterial blood pressure. Following hemorrhage, as a result of blood loss, blood pressure would rapidly decrease. This leads to a decrease in the firing rate of baroreceptors in response to less stretch. This signals the medullary cardiovascular areas to increase the activity of the sympathetic nerves to the heart, arterioles, and veins. This would cause the heart rate and the peripheral resistance to increase, all in an effort to bring the stroke volume, cardiac output, and arterial pressure back towards normal.

Question 81

Compared with resting levels of blood flow (ml/min), during strenuous exercise A) Blood flow to the heart, brain, and skeletal muscles would increase B) Blood flow to the kidneys and abdominal organs would decrease. C) Blood flow to the skin and brain would decrease. D) Blood flow to the skeletal muscles, abdominal organs, and skin will increase

Answer 81

B) Blood flow to the kidneys and abdominal organs would decrease. During exercise, there is a patterned redistribution of blood flow. Blood flow to the heart and exercising muscles increases dramatically (3.5 times in the heart and 10 times in skeletal muscle), whereas blood flow to kidneys and abdominal organs decreases (30% in kidneys). Blood flow to the brain does not change markedly but it does increase in the skin (4.5 times) to help in heat exchange.

Question 82

Which of the following does NOT enhance platelet aggregation leading to the formation of a platelet plug? A) Exposed collagen and von Willebrand factor. B) ADP C) Thromboxane A2 D) Prostacyclin E) Fibrinogen

Answer 82

D) Prostacyclin Prostacyclin is a potent inhibitor of platelet aggregation. Many different factors contribute to platelet aggregation including exposed collagen and von Willebrand factor, ADP, thromboxane A2, and fibrinogen.

Question 83

Which of the following blood contains the lowest oxygen? a. aorta b. left atrium c. right ventricle d. pulmonary veins e. systemic arterioles

Answer 83

c. right ventricle

Question 84

If other factors are equal, which of the following vessels has the lowest resistance? a. length=1cm; radius =1cm b. length=4cm; radius=1cm c. length=8cm; radius=2cm d. length=1cm; radius=2cm e. length=0.5cm; radius= 2cm

Answer 84

e. length=0.5cm; radius= 2cm

Question 85

Which of the following correctly ranks pressures during isovolumetric contraction during a normal cardiac cycle? a. left ventricular> aortic > left atrial b. aortic > left atrial > left ventricular c. left atrial > aortic > left ventricular d. aortic > left ventricular > left atrial e. left ventricular > left atrial > aortic

Answer 85

d. aortic > left ventricular > left atrial

Question 86

Which is not a characteristic of the body's capillaries? a. large total surface area b. small individual diameter c. thin walls d. high blood velocity e. highly branched

Answer 86

d. high blood velocity

Question 87

Which of the following would not result in tissue edema? a. an increase in the concentration of plasma proteins b. an increase in the pore size of systemic capillaries c. an increase in venous pressure d. blockage of lymph vessels e. a decrease in the protein concentration of the plasma

Answer 87

a. an increase in the concentration of plasma proteins

Question 88

Which statement is true when comparing systemic and pulmonary circuits? a. The blood flow is greater through the systemic. b. The blood flow is greater through the pulmonary c. The absolute pressure is higher in the pulmonary d. The blood flow is the same in both e. The pressure gradient is the same in both.

Answer 88

d. The blood flow is the same in both Pressures are higher in systemic but flow is the same.

Question 89

What is mainly responsible for the delay between the atrial and ventricular contractions? a. the shallow slope of the AV node pacemaker potentials b. slow action potential conduction velocity of AV node cells. c. slow action potential conduction velocity along atrial muscle cell membranes d. slow action potential conduction in the purkinje network of the ventricles e. greater parasympathetic nerve firing to the ventricles than to the atria.

Answer 89

b. slow action potential conduction velocity of AV node cells. Slow propagation though the AV node delays the beginning of ventricular contraction.

Question 90

Which of the following would help to restore homeostasis in the first few moments after person's MAP has become elevated? a. a decrease in baroreceptor action potential frequency b. a decrease in action potential frequency along parasympathetic neurons in the heart c. an increase in action potential frequency along sympathetic neurons in the heart d. a decrease in action potential frequency along sympathetic neurons to arterioles e. an increase in in total peripheral resistance.

Answer 90

d. a decrease in action potential frequency along sympathetic neurons to arterioles Reduced firing to the arterioles would reduce total peripheral resistance and reduce MAP towards normal.

Question 91

Which is false about L-type Ca channels in cardiac ventricular cells? a. They are open during the plateau of the action potential b. They allow Ca entry that triggers SR Ca release. c. They are found in the t-tubules in the membrane d. They open in response to depolarization of the membrane. e. They contribute to the pacemaker potential.

Answer 91

e. They contribute to the pacemaker potential. Ventricular muscle cells do not have pacemaker potential and L-type channel is not open during this phase of an AP in autorhythmic cells.

Question 92

Which correctly pairs an ECG phase with the cardiac event? a. P wave: depolarization of the ventricles b. P wave: depolarization of the AV node c. QRS wave: depolarization of the ventricles d. QRS wave: Repolarization of the ventricles e. T wave: repolarization of the atria

Answer 92

c. QRS wave: depolarization of the ventricles

Question 93

When a person engages in prolonged, strenous exercise: a. blood flow to the kidneys is reduced b. cardiac output is reduced c. TPR increases d. systolic arterial blood pressure is reduced e. blood flow to the brain is reduced

Answer 93

a. blood flow to the kidneys is reduced

Question 94

Which would cause greater increase in resistance to flow? a. doubling the blood viscosity b. halving the tube radius

Answer 94

b. halving the tube radius - (4th power)

Question 95

If all plasma Ca channels in cardiac muscle cells were blocked with a drug, what would happen to the muscles action potentials and contraction?

Answer 95

The plateau of the AP would be absent. The signal for the release of Ca from the SR is dependent upon the Ca entering across the plasma membrane.

Question 96

A person is taking a drug that blocks beta-adrenergic receptors. What changes in cardiac function will the drug cause?

Answer 96

Decreased heart rate and contractility. These are the effects mediated by the sympathetic nerves on beta-adrenergic receptors of the heart.

Question 97

A person is given a drug that doubles the blood flow to the kidneys but does not change MAP. What must the drug be doing?

Answer 97

The drug has caused the arterioles in the kidney to dilate enough to reduce the resistance by 50%.

Question 98

A person is accumulating edema throughout the body. Average capillary pressure is 25mmHg and lymphatic function is normal. What is happening?

Answer 98

Low plasma protein. OR - capillary permeability to plasma proteins has increased- such as with a burn victim. Capillary pressure is lower than normal so it is not causing the edema.

Question 99

The following data was collected on an experimental animal during a drug treatment: Before: HR = 80bpm, SV =80mL/beat After: HR =100bpm, SV 64mL/beat TPR remains unchanged. What has the drug done to MAP?

Answer 99

Nothing. CO and TPR are the same so - CO x TPR = MAP remains the same. MAP depends on CO but NOT on the combination of HR and SV that creates CO.

Question 100

When the nerves in the arterial baroreceptors are cut, what happens to MAP?

Answer 100

It increases because it is not getting signal and the medulla reflexively responds by increasing MAP.

Question 101

What happens to hematocrit several hours after hemorrage?

Answer 101

It decreases. IF starts entering capillaries to expand blood volume which dilutes Hct as it is too soon for new RBC to be produced.

Question 102

If Patm= 0mmHg and Palv= -2mmHg, the: a. transpulmonary pressure (Ptp) is 2 mmHg b. it is the end of the normal inspiration and there is no airflow c. it is the end of normal expiration and there is no airflow d. transpulmonary pressure is -2 mmHg e. air is flowing into the lung.

Answer 102

e. air is flowing into the lung. The pressure gradient is driving air inward from the atmosphere to the lungs.

Question 103

Transpulmonary pressure increases by 3 mmHg during normal inspiration. In subject A, 500mL of air is inspired. In subject B, 250 mL of air is inspired for the same change in Ptp. Which is true? a. The compliance of the lung in subject B is less than that of Subject A. b. The airway resistance of subject A is greater than that of subject B. c. The surface tension of the lung in subject B is less than that in subject A. d. The lung of subject A is deficient in surfactant e. The compliance cannot be estimated from the data given.

Answer 103

a. The compliance of the lung in subject B is less than that of Subject A. For the same change in transpulmonary pressure, a less compliant lung will have smaller change in volume. (stiffer)

Question 104

Which of the following will increase Po2? a. increase in metabolism and no change in alveolar ventilation b. breathing air with 15% oxygen at sea level c. increase in alveolar ventilation matched by an increase in metabolism d. increased alveolar ventilation with no change in metabolism e. carbon monoxide poisoning

Answer 104

d. increased alveolar ventilation with no change in metabolism

Question 105

Which of the following will cause the largest increase in systemic arterial oxygen saturation in the blood? a. an increase in red cell concentration of 20% b. breathing 100% O2 in a normal subject at sea level. c. an increase in arterial Po2 from 40 to 60 mmHg d. hyperventilation in a healthy subject at sea level. e. breathing gas at 5% CO2, 21% O2, and 74% N at sea level.

Answer 105

c. an increase in arterial Po2 from 40 to 60 mmHg

Question 106

Which of the following is not true about asthma? a. The basic defect is chronic airway inflammation b. It is always caused by an allergy c. the smooth airway muscle is hyperresponsive d. It can be treated with inhaled steroids e. It can be treated with a bronchodilator

Answer 106

b. It is always caused by an allergy Can be cold-air or exercise induced

Question 107

Which of the following is true? a. peripheral chemoreceptors increase firing with low arterial Po2 but are not sensitive to an increase in arterial Pco2. b. The primary stimulus to the central chemoreceptors is low Po2. c. Peripheral chemoreceptors increase firing during metabolic alkalosis. d. THe increase in ventilation during exercise is due to a decrease in arterial Po2. e. Peripheral and central chemoreceptors both increase firing when Pco2 increases.

Answer 107

e. Peripheral and central chemoreceptors both increase firing when Pco2 increases. Respiratory acidosis (increase in blood Pco2 and decrease in pH) is a major stimulus to ventilation. This is mediated by the afferents from the peripheral chemoreceptors and by an increase in central chemoreceptor activity.

Question 108

Ventilation-Perfusion inequalities lead to hypoxemia because: a. the relationship between Pco2 and the content of CO2 in blood is sigmoidal. b. a decrease in ventilation-perfusion matching in a lung region causes pulmonary arteriolar vasodilation in that region. c. increases in ventilation cannot fully restore O2 content in areas with low ventilation-perfusion matching. d. increases in ventilation cannot normalize Pco2. e. pulmonary blood vessels are not sensitive to changes in Po2.

Answer 108

c. increases in ventilation cannot fully restore O2 content in areas with low ventilation-perfusion matching.

Question 109

After the expiration of a normal tidal volume, a subject breathes in as much air as possible. The volume of air inspired is the: a. inspiratory reserve volume b. vital capacity c. inspiratory capacity d. total lung capacity e. functional residual capacity

Answer 109

c. inspiratory capacity Inspiratory capacity = tidal volume + inspiratory reserve volume

Question 110

A patient is unable to make surfactant. To inhale a normal tidal volume, will her intrapleural pressure have to be more or less subatmospheric during inspiration, relative to a healthy person?

Answer 110

More subatmospheric. Decreased surfactant causes lungs to be less compliant (stiffer). Greater transpulmonary pressure is required to expand them. (newborn)

Question 111

What is normal alveolar ventilation? a. 1000mL/min b. 2000mL/min c. 4000mL/min d. 6000mL/min

Answer 111

c. 4000mL/min

Question 112

A person breathing room air has alveolar Po2 of 105mmHg and arterial Po2 of 80mmHg. Could hypoventilation be due to respiratory muscle weakness to produce these values?

Answer 112

No Hypoventilation - both alveolar and arterial Po2 are decreased to the same degree. This person has normal alveolar ventilation and the person is not hypoventilating. They may have a shunting issue, hole in heart wall to cause this.

Question 113

Which of the following have higher values in systemic venous blood than in systemic arterial blood? a. plasma CO2 b. erythrocyte Pco2 c. plasma bicarbonate concentration d. erythrocyte bicarbonate concentration e. plasma hydrogen ion concentration f. erthyrocyte hydrogen ion concentration g. erythrocyte carbamino concentration

Answer 113

All of them. Venous blood contains all of the metabolites.

Question 114

If the spinal cord were severed where it joins the brainstem, what would happen to respiration?

Answer 114

It would cease. Respiration depends on descending input from the medulla to the nerves in the diaphragm and inspiratory intercostal muscles.

Question 115

``` As air enters the trachea and descends toward the lungs, gas exchange with the blood first begins in the A) Bronchioles B) Alveolar ducts C) Alveolar sacs D) Respiratory bronchioles ```

Answer 115

D) Respiratory bronchioles

Question 116

Boyle's law describes the relationship between the pressure exerted by a fixed number of gas molecules and the temperature. A) True B) False

Answer 116

B) False Boyle's law describes the relationship between the pressure exerted by a fixed number of gas molecules and the volume at some constant temperature. In other words, at any given temperature, as the volume decreases, the pressure increases and vice versa.

Question 117

``` At the beginning of an inspiration A) Pip decreases B) Ptp decreases C) Palv increases D) Patm increases ```

Answer 117

A) Pip decreases At the beginning of an inspiration, the intrapleural pressure (Pip) decreases. This leads to an increase in transpulmonary pressure (Ptp) because Ptp = Palv - Pip. As the lungs expand, the alveolar pressure (Palv) decreases causing air to flow inward.

Question 118

Elastic recoil of the lungs A) Prevents the lungs from collapsing B) When combined with the elastic recoil properties of the chest wall, creates the positive intrapleural pressure C) Forces air to enter the lungs during expiration D) Opposes expansion of the lungs

Answer 118

D) Opposes expansion of the lungs Recoil would cause the alveoli to collapse, but due to the elastic recoil properties of the chest wall, there is a subatmospheric (negative) intrapleural pressure created that opposes collapse of the lungs. Elastic recoil also causes air to leave the lungs during expiration, when the transpulmonary pressure decreases.

Question 119

At the end of an unforced expiration A) The pressure of the intrapleural cavity is the same as atmospheric pressure B) The alveolar pressure is less than atmospheric pressure C) The tendency for the lungs to recoil to an unstretched state is balanced by the tendency of the chest wall to expand D) Alveolar pressure minus intrapleural pressure is zero

Answer 119

C) The tendency for the lungs to recoil to an unstretched state is balanced by the tendency of the chest wall to expand At the end of expiration, the elastic recoil forces of the lungs are balanced by the forces tending to expand the chest wall. Intrapleural pressure is negative as a result of these forces tending to pull the lungs away from the chest wall. Alveolar pressure is equal to atmospheric pressure, and therefore there is no pressure gradient moving air in or out of the lungs.

Question 120

Which of the following is true of a person with abnormally low lung compliance? The person A) Must work harder than a normal person to inspire the same amount of air B) Must have a greater than normal intrapleural pressure to inspire the same amount of air C) May have thinner lung tissues than a normal person D) May have less alveolar surface tension than a normal person E) May have a defect in type I alveolar cells

Answer 120

A) Must work harder than a normal person to inspire the same amount of air Lung compliance refers to the magnitude of the change in lung volume produced by a given change in trans-pulmonary pressure. This person would have to work harder to inspire the same amount of air as a person with normal lung compliance. A person with abnormally low lung compliance would need greater than normal trans-pulmonary pressure to inspire the same amount of air, so there would need to be lower (more negative) intrapleural pressure. They may have stiffer lung tissue, more surface tension, and that person may have less surfactant. These would cause a decrease in lung compliance.

Question 121

The respiratory disease that results from excessive constriction of the smooth muscle lining the airways is A) Asthma B) Emphysema C) Chronic bronchitis D) Chronic obstructive pulmonary disease

Answer 121

B) Emphysema Asthma is the result of excessive constriction of smooth muscle in the airways. Like asthma, the chronic obstructive pulmonary diseases, emphysema and chronic bronchitis, are characterized by decreased ventilation, but the causes are different. Emphysema is characterized by destruction of the alveoli and collapse of the lower respiratory passages, while chronic bronchitis is characterized by excessive mucous production.

Question 122

The vital capacity is the sum of A) Tidal volume + inspiratory reserve volume + expiratory reserve volume. B) Tidal volume + functional residual capacity. C) Tidal volume + residual volume. D) Inspiratory reserve volume + expiratory reserve volume.

Answer 122

A) Tidal volume + inspiratory reserve volume + expiratory reserve volume.

Question 123

A healthy young man has a resting tidal volume of 500 ml and an anatomic dead space of 150 ml. His breathing rate is 10 breaths/minute. He has a total lung capacity of 6000ml, and a residual volume of 1000ml. Which of the following statements is correct? A) His alveolar ventilation would be 5 L/minute B) Doubling the breathing rate would double his alveolar ventilation C) Doubling the depth of respiration (tidal volume) would double his alveolar ventilation D) His vital capacity is 5500ml E) His functional residual capacity is 5000ml

Answer 123

B) Doubling the breathing rate would double his alveolar ventilation If you multiply tidal volume by breathing rate you get minute ventilation, so minute ventilation is 500 ml x 10 breaths/min=5000 ml/minute. However, alveolar ventilation excludes the anatomic dead space, so alveolar ventilation is (500ml-150ml) x 10 breaths/min = 3500 ml/min. If you double his breathing rate, alveolar ventilation doubles; (500ml-150ml) ml x 20 breaths/min = 7000 ml/minute. Doubling the depth of respiration more than doubles alveolar ventilation; (1000ml-150ml) x 10 breaths/min = 8500 ml/min.

Question 124

``` The conducting airways have a volume of about 150ml which is not capable of exchanging gases with the blood. This is referred to as A) Physiological dead space B) Anatomical dead space C) Alveolar dead space D) Respiratory zone dead space ```

Answer 124

B) Anatomical dead space The sum of the alveolar dead space + the anatomical dead space = the physiologic dead space.

Question 125

``` n a mixture of gases the total pressure is simply the sum of the pressures of the individual gases, and the pressure each gas exerts is independent of the pressure the other gasses exert. This statement is called A) Boyle's law B) Henry's law C) Dalton's law D) Law of mass action ```

Answer 125

C) Dalton's law Boyle's law explains the relationship between pressure and volume. Henry's law states that the amount of gas dissolved in a liquid will be directly proportional to the partial pressure of the gas with which the liquid is in equilibrium. The Law of mass action explains the role of concentration of reactant and products in determining the rates and direction of a chemical reaction.

Question 126

Which of the following will result in an increase in the partial pressure of oxygen in the alveoli (PO2)? A) An increase in the PO2 in the surrounding air B) An increase in the rate of oxygen consumption by the cells of the body C) A decrease in the rate and depth of ventilation D) A decrease in anaerobic cellular respiration

Answer 126

A) An increase in the PO2 in the surrounding air An increase in the PO2 in the surrounding air will increase the PO2 in the alveoli. An increase in oxygen consumption and a decrease in rate and depth of ventilation would decrease PO2 in the alveoli. Anaerobic respiration does not have an effect on oxygen.

Question 127

Which of the following statements about ventilation-perfusion inequality is correct? A) Decreased alveolar PO2 leads to local vasoconstriction to decrease blood flow to the affected alveolus B) Increased capillary PO2 leads to local bronchoconstriction to decrease air flow to the affected alveolus C) Increased alveolar PO2 leads to local bronchoconstriction to decrease air flow to the alveolus D) Increased alveolar PCO2 leads to local vasoconstriction to decrease blood flow to the affected alveolus

Answer 127

A) Decreased alveolar PO2 leads to local vasoconstriction to decrease blood flow to the affected alveolus When airway blockage leads to a decrease in PO2 in a group of alveoli, local vasoconstriction will diverted blood flow away from those alveoli. Increased PO2 in capillaries or in alveoli would not lead to bronchoconstriction and reduced air flow to the alveoli. An increase in alveolar PCO2 indicates good alveolar function and would not lead to bronchoconstriction and reduced air flow to the alveolus.

Question 128

Which of the following stimuli would increase the flow of blood through a pulmonary capillary bed? A) Decreased PCO2 of the capillary blood B) Increased PO2 in the alveoli C) Increased PCO2 of the capillary blood D) Decreased PO2 of the alveoli

Answer 128

B) Increased PO2 in the alveoli Pulmonary capillaries respond differently from capillaries in other tissues. In response to increased PO2, pulmonary arterioles dilate, thereby promoting blood flow to the ventilated alveoli. This is an adaptive response and helps to move the inspired oxygen away from the lungs and into the tissues of the bodies.

Question 129

Which of the following statements regarding the transport of O2 in blood is true? A) Most of the O2 carried by blood is dissolved in plasma B) None of the O2 carried by blood is dissolved in plasma C) Most of the O2 carried by blood is bound to iron D) The PO2 of venous blood is greater than the PO2 of arterial blood

Answer 129

C) Most of the O2 carried by blood is bound to iron

Question 130

``` The amount of oxygen that leaves the hemoglobin and enters the tissues in a person at rest is approximately A) 10% B) 25% C) 50% D) 75% ```

Answer 130

B) 25%

Question 131

The affinity of hemoglobin for O2 is A) Decreased in rapidly metabolizing tissues B) Increased at higher than normal body temperatures C) Increased at higher than normal blood 2,3-DPG levels D) Decreased at more basic than normal blood pH

Answer 131

A) Decreased in rapidly metabolizing tissues The affinity of hemoglobin to bind O2 is decreased in tissues that are actively metabolizing, thereby promoting O2 delivery to tissues. An actively metabolizing tissue, such as contracting muscle tissue, tends to produce more acid (lactate, carbon dioxide) and also get warmer due to the heat of metabolism. The hemoglobin protein structure is adapted to have a lower affinity for oxygen in tissue environments that have higher temperature and acidity (lower pH), therefore releasing oxygen to the tissues. Another regulating factor is the concentration of a regulatory molecule called DPG (2,3-diphosphoglycerate). An increasing level of DPG causes a decrease in affinity of hemoglobin for oxygen. Affinity would be decreased by higher blood pH, a condition that occurs in the lungs tissue where greater affinity of hemoglobin for O2 facilitates binding of oxygen for transport away from the lungs to the tissues. Ventilation also creates a cooler environment in the lungs compared to tissues. This also helps increase binding of oxygen to hemoglobin.

Question 132

Which of the following conditions results in a shift from right to left in the Hb-O2 saturation curve? A) Increased acidity B) Increased temperature C) Blood flowing in capillaries to the alveoli D) Increased blood concentration of DPG E) Increased acidity, temperature, and blood concentration of DPG

Answer 132

C) Blood flowing in capillaries to the alveoli The Hb-O2 saturation curve shifts back to the left as a result of two major conditions, decreased acidity and decreased temperature. A shift to the left indicates increased affinity of hemoglobin for oxygen, a condition that results in the binding of oxygen to Hb. This condition is dominant in the lungs where metabolism is slow (reduced acid production) and the environment is cool due to ventilation. In the tissues where acid and heat are produced by metabolism, Hb affinity for O2 is low and oxygen is released to the tissues for use during oxidation (curve shifts right). These changes in affinity are properties of the Hb molecule, which changes its 3-D conformation in different acid and temperature condition. These changes are adaptive to the role of Hb in oxygen transport.

Question 133

``` Which of the following is the "most important" (most effective) mode of transport of carbon dioxide in the blood? A) As bicarbonate B) As dissolved carbon dioxide C) Bound to hemoglobin D) As carbonic acid ```

Answer 133

A) As bicarbonate Most carbon dioxide (60-65%) is transported as bicarbonate. Carbon dioxide reacts with water to form carbonic acid, which is then dissociated to form bicarbonate and hydrogen ions. This reaction is catalyzed with the help of the enzyme carbonic anhydrase, which is present in the red blood cell in high amounts. In the lungs, this reaction goes in the opposite direction. Approximately 10% of the carbon dioxide is transported as dissolved carbon dioxide.

Question 134

``` Hemoglobin has the ability to bind and carry all of the following molecules except: A) Hydrogen B) Carbon dioxide C) Oxygen D) Carbon monoxide E) Carbonic acid ```

Answer 134

E) Carbonic acid

Question 135

``` The major automatic (involuntary) regulatory centers for respiration, especially the inspiratory centers, are located in the _________ region of the brain. A) Spinal cord B) Cerebral cortex C) Pons D) Medulla E) Cerebellum ```

Answer 135

D) Medulla The hypothalamus and cerebral cortex also have influence over the medullar centers. The cortex is involved in voluntary control of respiration and the hypothalamus over exercise induced changes and those occurring during emotional states.

Question 136

``` Which of the following does NOT contain chemoreceptors regulating the rate of respiration? A) Aortic bodies B) Carotid bodies C) Brain medulla D) Heart ventricles ```

Answer 136

D) Heart ventricles Chemical mechanisms in the carotid and aortic bodies sense changes in oxygen levels and communicate these to the sensory neurons, which in turn inform the brain respiratory centers. Action potential frequency in these neurons increases with decreasing blood oxygen levels and increasing blood hydrogen levels. Activation of respiratory centers increases rate of respiration, bringing in more oxygen and compensating for reduced blood oxygen. The chemoreceptors in the medulla are mainly sensitive to the hydrogen ions produced by the reaction of carbon dioxide with water. A high level of carbonic anhydrase, the enzyme which catalyzes this reaction, is present in medullary chemoreceptor neurons. Increased carbon dioxide results in an increase in hydrogen production and stimulation of these chemoreceptor neurons which in turn stimulate the inspiratory neurons to increase the rate of ventilation. This causes removal of excess blood carbon dioxide by the lungs.

Question 137

``` Central chemoreceptors, which participate in the regulation of ventilation, respond most directly to A) PO2 B) PCO2 C) H+ D) Carbonic acid ```

Answer 137

C) H+ Central chemoreceptors respond directly to H+. However, the increase in the concentration of H+ is the result of diffusion of carbon dioxide from the blood into the medulla and the conversion of carbon dioxide to bicarbonate and hydrogen.

Question 138

``` Carbon monoxide is a gas that binds to heme iron with a higher affinity than does oxygen but has no effect on the partial pressure of oxygen. Breathing a gas mixture with normal sea level partial pressure of oxygen but with elevated carbon monoxide would produce A) Hypoventilation B) Hypoxic hypoxia C) Histotoxic hypoxia D) Anemic hypoxia E) Hypotension ```

Answer 138

D) Anemic hypoxia

Question 139

An appropriate adaptation to a long-term stay at high altitude is A) Reduced hemoglobin concentration in blood B) Increased erythropoiesis in bone marrow and red cell population in the blood C) Increased alveolar ventilation D) Increased partial pressure of oxygen in blood

Answer 139

B) Increased erythropoiesis in bone marrow and red cell population in the blood

Question 140

Which of the following structures composes the renal corpuscle? A) Glomerular capillaries B) Bowman's capsule C) Afferent arteriole D) Glomerular capillaries and Bowman's capsule E) Afferent arteriole and Bowman's capsule

Answer 140

D) Glomerular capillaries and Bowman's capsule

Question 141

Which of the following components of the filtration membrane form the filtration slits? A) The capillary endothelial cells B) The basement membrane C) The podocyte cells D) The capillary endothelial cells and the podocyte cells

Answer 141

C) The podocyte cells Filtration slits are the gaps that exist between the foot processes of the podocyte cells as they make contact with the basement membrane.

Question 142

The juxtaglomerular apparatus is composed of the A) Juxtaglomerular cells B) Macula densa C) Mesangial cells D) Juxtaglomerular cells and mesangial cells E) Juxtaglomerular cells and macula densa

Answer 142

E) Juxtaglomerular cells and macula densa

Question 143

``` Which of the following is NOT a basic renal process? A) Glomerular filtration B) Tubular reabsorption C) Tubular secretion D) Erythropoietin production ```

Answer 143

D) Erythropoietin production Erythropoietin production is an endocrine function of the kidney.

Question 144

Which of the following will cause an increase in the glomerular filtration rate? A) Increasing the hydrostatic pressure of the blood B) Increasing the colloid osmotic pressure of the blood C) Increasing sympathetic nerve discharge to glomerular afferent arterioles D) Efferent arteriole vasodilation

Answer 144

A) Increasing the hydrostatic pressure of the blood

Question 145

The entire volume of plasma in the average person is filtered by the kidney approximately every 30 minutes. A) True B) False

Answer 145

A) True

Question 146

Which of the following is true about the reabsorption process of substances such as sodium, glucose and amino acids in the nephron? A) It involves the Bowman's capsule B) It is restricted to the loop of Henle C) It occurs mainly in the proximal convoluted tubules D) It occurs mainly by osmosis

Answer 146

C) It occurs mainly in the proximal convoluted tubules

Question 147

In the process of reabsorption via transporters, when the binding sites on a renal transport protein become saturated A) The transport maximum for that transporter has been reached B) The substance being transported will begin to decrease in concentration in the urine C) The rate of transport will increase in order to reabsorb even more of the substance being transported D) The transporters will stop functioning

Answer 147

A) The transport maximum for that transporter has been reached

Question 148

Reabsorption of glucose in the kidney proximal tubules occurs by A) Diffusion, depending on plasma glucose concentration B) An active transport process that is linked to sodium reabsorption C) An active transport process that is linked to amino acid transport D) Active transport with no link to the transport of any other substance

Answer 148

B) An active transport process that is linked to sodium reabsorption

Question 149

``` Which of the following substances is NOT commonly secreted by the renal tubules? A) Sodium ions B) Potassium ions C) Drugs such as penicillin D) Hydrogen ions ```

Answer 149

A) Sodium ions Sodium is reabsorbed from the filtrate, but never secreted. Each of the others is commonly secreted into the filtrate. Reference: [See p. 486].

Question 150

When the clearance of a molecule is less than the glomerular filtration rate (GFR) of that molecule, which of the following statements regarding that molecule is true? A) It is filtered and is not subject to reabsorption or secretion B) It is filtered and is partially reabsorbed C) It is filtered and is partially secreted D) It is totally filtered

Answer 150

B) It is filtered and is partially reabsorbed Whenever the clearance of a substance is less than GFR, that substance must undergo reabsorption. If its clearance matched GFR, then it was neither reabsorbed nor secreted. If its clearance was greater than GFR, then it must have been secreted. There is no information to determine if it is totally filtered.

Question 151

Stretch receptors located in the bladder wall are important for micturition. A) True B) False

Answer 151

A) True Micturition or urination describes the process by which urine is ejected from the bladder. As the bladder fills with urine, stretch receptors located in the muscular wall of the bladder become stimulated. Afferent fibers from these stretch receptors send signals to the spinal cord and stimulate efferent parasympathetic neurons which cause the detrusor muscles to contract, expelling urine from the bladder through the urethra.

Question 152

In all nephron segments, the active transport of sodium by tubular cells is accomplished by the action of the Na+/K+ ATPase pump in the basolateral membrane. A) True B) False

Answer 152

A) True

Question 153

Movement of water out of the collecting ducts takes place by bulk flow. A) True B) False

Answer 153

B) False Movement of water out of the collecting ducts occurs by osmosis. Water moves through aquaporins under the force provided by an osmotic gradient.

Question 154

Which of the following is NOT associated with the increase in hypoosmotic urine production in persons with diabetes insipidus? A) Failure of the posterior pituitary to secrete vasopressin B) A blood glucose concentration that exceeds transport maximum in the nephron resulting in glucose, and thus water, remaining in the urine C) The inability of the kidneys to respond to vasopressin D) The inability of the kidneys to respond to ADH

Answer 154

B) A blood glucose concentration that exceeds transport maximum in the nephron resulting in glucose, and thus water, remaining in the urine Excessive glucose in the blood results in an osmotic dieresis. When blood glucose concentrations exceed the transport maximum of glucose, the glucose remaining in the filtrate causes water to remain in the filtrate as well. This condition is usually the result of diabetes mellitus. Central diabetes insipidus results from a lack of production of vasopressin by the hypothalamus or its release from the posterior pituitary.

Question 155

Which of the following does NOT contribute to the hypertonic medullary interstitium? A) Solute reabsorption in the ascending limb of the loop of Henle B) Sodium reabsorption in the distal tubule C) Urea reabsorption from the proximal tubule D) Urea recycling between the loop of Henle and the collecting duct

Answer 155

C) Urea reabsorption from the proximal tubule The medullary interstitium is hypertonic due to the action of the countercurrent multiplier and the recycling of urea between the loop of Henle and the collecting duct.

Question 156

``` Which of the following is a hormone formed in the blood as a result of converting a non-functional precursor protein into a functional protein which causes vasoconstriction, resulting in increased arterial pressure? A) Renin B) Aldosterone C) Angiotensin D) Vasopressin ```

Answer 156

C) Angiotensin Angiotensin has a vasoconstricting effect. Angiotensin I is formed in the blood by the action of the kidney hormone renin which enzymatically converts angiotensinogen to angiotensin I. The latter is then further converted to a more potent peptide, angiotensin II by angiotensin-converting enzyme produced by endothelial cells of capillaries. Angiotensin II causes vasoconstriction in the peripheral blood vessels, including the kidney, thus increasing blood pressure. Aldosterone is a steroid hormone formed by the adrenal cortex ADH is a peptide hormone made in the hypothalamic neurons and released at the site of the posterior pituitary.

Question 157

``` The hormone that most directly influences Na+ reabsorption in the collecting duct is A) Aldosterone B) Angiotensin C) Renin D) Vasopressin ```

Answer 157

A) Aldosterone Renin is released in response to low sodium concentrations and functions as the enzyme that converts angiotensinogen to angiotensin I. Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE). Angiotensin II stimulates adrenal cells to secrete aldosterone. Vasopressin plays no role in Na+ reabsorption.

Question 158

Which of the following drugs would be most effective in treating hypertension? A) An alpha-adrenergic agonist B) An ADH agonist C) An angiotensin-converting enzyme inhibitor D) A stimulator of aldosterone synthesis

Answer 158

C) An angiotensin-converting enzyme inhibitor

Question 159

``` Which of the following hormones would act on the kidney collecting ducts to increase water reabsorption as would occur during dehydration (increased plasma osmolarity)? A) Aldosterone B) Angiotensin C) Renin D) ADH (vasopressin) E) ANP (atrial natriuretic peptide) ```

Answer 159

D) ADH (vasopressin) ADH or anti-diuretic hormone, also called vasopressin, acts on the collecting ducts, increasing their permeability to water, leading to increased reabsorption of water and thus decreasing its loss in the urine. Aldosterone can also help increase water reabsorption but only by increasing reabsorption of sodium (and thus water) in the proximal and distal tubules. ANP or atrial natriuretic peptide would lead to a decrease in reabsorption of sodium and water.

Question 160

Which of the following statements regarding renal handling of water by the kidneys is correct? A) In the absence of vasopressin, urine is isoosmotic with plasma. B) In the absence of vasopressin, water cannot be reabsorbed in the proximal tubules. C) In the absence of vasopressin, the cortical collecting ducts have very low permeability to water. D) In the absence of vasopressin, the distal tubules secrete water.

Answer 160

C) In the absence of vasopressin, the cortical collecting ducts have very low permeability to water.

Question 161

Despite the presence of the Na+/K+ ATPase pumps in the basolateral membrane of most nephron tubules, the secretion of K+ into the lumen is limited to the cortical collecting duct cells because only these cells have luminal K+ leak channels. A) True B) False

Answer 161

A) True

Question 162

Much like small organic nutrients, calcium reabsorption by the kidney occurs in the proximal tubule and is not subject to regulation. A) True B) False

Answer 162

B) False While the kidney readily reabsorbs about 60% of the filtered calcium, the remainder of calcium reabsorption is under the control of parathyroid hormone (PTH).

Question 163

``` Which of the following substances is NOT involved in the buffering functions of the kidney? A) Oxalate B) Phosphate C) Ammonia D) Bicarbonate ```

Answer 163

A) Oxalate

Question 164

Which of the following statements regarding renal regulation of hydrogen-ion concentration by the kidneys is true? A) Renal regulation of extracellular H+ concentration is dependent upon regulating the amount of hydrogen ion filtered by the kidneys. B) Renal regulation of extracellular H+ concentration is dependent upon regulating the amount of hydroxides secreted by the kidneys C) Renal regulation of extracellular H+ concentration is accomplished in part by regulating the amount of bicarbonate ion excreted by the kidneys D) Most of the H+ excreted in the urine is bound to bicarbonate

Answer 164

C) Renal regulation of extracellular H+ concentration is accomplished in part by regulating the amount of bicarbonate ion excreted by the kidneys

Question 165

The presence of this substance in the urine is considered a sign of kidney disease or kidney disorder. A) Urea B) Electrolytes (e.g. sodium and potassium) C) Plasma proteins (e.g., albumins) D) Glucose

Answer 165

C) Plasma proteins (e.g., albumins)

Question 166

Where is the Na/Glucose symporter located? a. distal tubule b. Bowman's capsule c. proximal tubule d. ascending loop of henle

Answer 166

c. proximal tubule

Question 167

What is the primary transporter located in the ascending loop of Henle? a. Na/K ATPase b. Na/HCO3 symporter c. Na/K/Cl loop transporter d. Cl/HCO3 antiporter

Answer 167

c. Na/K/Cl loop transporter

Question 168

What type of control is the body's way of determining to keep or excrete water? a. Neural b. Hormonal c. Reflexively

Answer 168

b. Hormonal save salt: aldosterone save water: ADH to increase BP

Question 169

How does the brain know when to retain fluid?

Answer 169

By Na levels sensed by chemoreceptors on the hypothalamus. A high osmolarity signals the pituitary to release ADH there by removing aquaporins from the collecting ducts, decreasing water excretion and concentrating the urine while making the blood more isoosmotic.

Question 170

At which site along the tubules does the kidney determine to keep or excrete Na?

Answer 170

In the collecting ducts via hormonal control of aldosterone.

Question 171

The K in blood is sensed by: | _______ __________

Answer 171

Adrenal Gland - which releases aldosterone to increase K excretion.

Question 172

Where is the supply of Phosphate and Ca derived from?

Answer 172

Bone via hydroxyapatite

Question 173

Where are the receptors for PTH in the body?

Answer 173

Kidney

Question 174

Do we secrete Ca into the urine?

Answer 174

No

Question 175

Where do we reabsorb Ca in the kidney system?

Answer 175

Proximal Tubules

Question 176

What are the 3 ways to increase plasma Ca?

Answer 176

1. PTH signals Ca release from bone 2. Final hydroxylation of Vit D in kidney enhances Ca uptake in GI tract. 3. Increased Ca reabsorption in kidney and decreased excretion.

Question 177

Where do we buffer H ions?

Answer 177

``` Hemoglobin Intracellular proteins Bicarbonate Phosphate Albumin ```

Question 178

An acidotic state will: a. increase Ca levels b. decrease Ca levels

Answer 178

a. increase Ca levels

Question 179

An alkalotic state will: a. increase Ca b. decrease Ca

Answer 179

b. decrease Ca - because more of it is bound to Albumin

Question 180

How is renin released from juxtaglomerular cells? | 3 ways

Answer 180

1. Hypotension- do not stretch the afferent arterioles so there is a release of renin to make angiotensin 1 & 11 to cause constriction. 2. Sympathetic innervation causes the release of renin. 3. Macula densa cells- change overall dilation by the release of adenosine which affects renin.