Exam 3 Flashcards
(174 cards)
1
Q
What are the five types of blood vessels?
A
Arteries, Arterioles, Capillaries, Venules, and Veins
2
Q
Arteries
A
Large, thick-walls elastic tubes; carry blood Away from the heart
3
Q
Arterioles
A
Much smaller than arteries and are very muscular; have a major role in control of blood pressure
4
Q
capillaries
A
Very small, thin-walled; exchange gases and nutrients with other cells or lung
5
Q
Venules
A
Same size as arterioles, but less muscular; carry blood towards the heart
6
Q
Veins
A
Large with thinner walls; carry blood back to the heart
7
Q
Endocardium
A
Thin inner layer of epithelial cells
8
Q
Myocardium
A
Thick muscular walls of the heart
9
Q
Epicardium
A
Thin outer layer of connective tissue
10
Q
Pericardium
A
thin connective tissue sac surrounding the heart
11
Q
True or False: Mammals have complete separation of oxygenated and deoxygenated blood
A
True
12
Q
Atrioventricular (AV) Valves
A
Open from atria into ventricles; allow the transport from one chamber to another
13
Q
What are the two AV valves?
A
The tricuspid and bicuspid valves
14
Q
Semilunar valves
A
Open from ventricles into the great arteries
15
Q
What are the names of the semilunar valves?
A
Pulmonary and aortic valves
16
Q
Describe briefly the Systemic Loop
A
Left ventricle –> Body Tissue –> Right atrium
17
Q
What is the major artery of the systemic Loop?
A
The aorta
18
Q
What are the major veins of the systemic loop?
A
The Superior vena cava and the inferior vena cava
19
Q
Superior Vena cava
A
Brings blood back from the head, neck, and arms
20
Q
Inferior Vena Cava
A
Brings blood back from the lower body
21
Q
Describe briefly the Pulmonary Loop.
A
Right ventricle –> Lungs –> Left atrium
22
Q
What is the major artery of the pulmonary loop?
A
The pulmonary arteries
23
Q
What are the major veins of the pulmonary loop?
A
The pulmonary veins
24
Q
Left-to-Right Shunts
A
Congenital defect where portion of the left ventricular output goes back to the lungs instead of going to the systemic loop
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Septal Effect
Type of left-to-right shunt; hole in the interventricular septum
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Patent ductus arteriosis
type of left-to-right shunt; ductus arteriosus connecting aorta with pulmonary arteries fails to close at birth
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What typically happens to prevent the phenomenon of patent ductus arteriosis?
The reversal of blood flow through the ductus arteriosus at birth causes its closure within a few hours.
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What happens when the ductus arteriosus does NOT close shortly after birth?
Blood flows from the aorta into the pulmonary artery; see patent ductus arteriosis
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What does it mean for the heart to be autorythmic?
It stimulates its own action potentials
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How does the resting membrane potential of heart muscle differ from that of skeletal muscle?
The resting membrane potential of heart muscle is more negative, with a higher K+ permeability at rest
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Ryanodine
Regulates calcium release from sarcoplasmic reticulum
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L-Type Ca2+ channels
Larger, long-lasting, steady current
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T-Type Ca2+ Channels
Shorter current, transient
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Rising phase of heart impulse conduction
The opening of Na+ channels
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Plateau phase of heart impulse conduction
Initial decrease in K+ permeability and delay in opening of K+ channels; opening of Ca2+ channels in cell membrane and sarcoplasmic reticulum
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Falling phase of heart impulse conduction
Opening of K+ channels
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Why is there only 1% of cardiac muscle cells specialized for initiating and conducting action potentials?
They are self-excitatory, have few contractile proteins, and have a specific conduction pathway
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Sinoatrial (SA) Node
Normal pacemaker of heart located in upper right atrium; cells are specialized for initiation of action potentials
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Pacemaker Potential
Gradual, spontaneous depolarization of cardiac pacemaker cells; due to slow leak of NA+ ions
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Action Potential (of cardiac cells)
Due to opening of Ca2+ channels
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Describe the impulse conduction of of heart
1. Pacemaker cells in SA node spontaneously depolarizes
2. Impulse spreads downward to left across both atria via gap junctions
3. Ventricles are separated from atria by nonconducting connective tissue
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Electrocardiogram (ECG)
Recording of the electrical activity of the heart
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P wave (of ECG)
Represents atrial depolarization (atrial excitation)
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QRS Complex (of ECG)
Represents ventricular depolarization (ventricular excitation)
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T Wave (of ECG)
Represents ventricular repolarization (ventricular relaxation)
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What are the general principles of the cardiac cycle?
1. Contraction of the myocardium generates pressure changes that result in the orderly movement of blood
2. Blood flows from high pressure to low pressure
3. Events on the right and left sides of the heart are the same, but pressure is lower on the right
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systole
period of ventricular contraction
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Diastole
Period of ventricular relaxation; typically longer than systole
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What are the phases of the cardiac cycle?
1. Passive filling
2. Atrial contraction
3. Isovolumetric ventricular contraction
4. Ejection
5.
Isovolumetric ventricular relaxation
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What are the characteristics of passive filling?
1. Atria and ventricles are relaxed, and ventricular pressure = 0.
2. AV valves are open
3. Blood flows from veins into atria and ventricles
4. Aortic and pulmonary valves are closed
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What are the characteristics of Atrial contraction?
1. Late diastole
2. SA node depolarizes
3. Wave of depolarization spreads across both atria
4. Completion of ventricular filling (end diastolic volume is ~135 mL)
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What are the characteristics of isovolumetric ventricular contraction?
1. Early systole
2. Ventricular depolarization (AP conducts through AV node, down bundle of His, and along Perkinje fibers)
3. Ventricles contract
4. Increasing pressure closes AV valves
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What are the characteristics of ejection?
1. Most of systole
2. Ventricular depolarization
3. Aortic and pulmonary valves open
4. 2/3 of blood is ejected from each ventricle (Systolic b.p. = 120 mmHg)
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Stroke volume
Volume of blood ejected by each ventricle in a single beat
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Ejection fraction
Stroke volume (SV) / EDV
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What are the characteristics of isovolumetric ventricular relaxation?
1. Early diastole
2. Wave of repolarization across ventricles
3. Ventricles relax
4. Ventricular pressure falls below atrial pressure (semilunar valves close)
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How long is a NORMAL systole?
About 0.3 seconds
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How long is a NORMAL diastole?
About 0.5 seconds
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What is the normal systemic arterial blood pressure?
120/80 mmHg
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What is normal pulmonary arterial blood pressure?
25/8 mmHg
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What would happen if the pulmonary arterial blood pressure was any higher than the normal 25/8 mmHg?
It would force fluid into the lungs
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Coronary Heart Disease
Any narrowing or blockage of coronary arteries
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Ischemia
Insufficient blood flow to an organ
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Myocardial ischemia
Insufficient blood flow to a part of the myocardium
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Silent Ischemia
No symptoms, but it is there; heart rate is higher than normal (75-80% of ischemic episodes are not painful)
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Angina pectoris
Severe pain in the chest and left arm
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How can angina pectoris be treated/controlled?
With nitrates
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Myocardial infarction
Heart attack; Complete blockage of blood flow to myocardium
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What are the most common causes of a heart attack?
Atherosclerosis
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What might occur due to the impaired impulse conduction through the heart during a heart attack?
Ventricular fibrillation
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What method is used after a heart attack if no pulse can be found?
Electrical defibrillation, paired with the injection of clot-dissolving drugs
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Angiogram
Inject dye into coronary circulation and then x-ray the heart for blocked arteries
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What are the different ways to treat people suffering from coronary heart disease?
1. Balloon angioplasty
2. Stent
3. Mechanical drilling of blockage
4. Coronary artery bypass surgery
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What is systolic BP?
Arterial blood pressure at its highest point in the cardiac cycle
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What is diastolic BP?
Arterial blood pressure at its lowest point in the cardiac cycle
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What factors influence the resistance of flow through blood vessels?
1. Blood viscosity
2. Total blood vessel length
3. Blood vessel diameter (****)
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True or False: Absolute pressure values are relevant to flow rate
FALSE. They are irrelevant
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What happens to flow when the radius of the vessel is halved?
It decreases 16-fold
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Stephen Hales
Made the first direct measurement of blood pressure; tied a horse to a gate and cannulated the carotid artery
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Sphygmomanometer
Measures blood pressure; no sound above systolic BP or below diastolic BP, but below systolic and above diastolic results in tapping sound
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Pulse pressure
Increase in arterial blood pressure produced by ventricular ejection
(Pulse pressure) = (Systolic BP) - (Diastolic BP)
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Mean arterial pressure (MAP)
Average arterial blood pressure over the whole cardiac cycle
(MAP) = (Diastolic BP) + 1/3(Pulse Pressure)
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Cardiac Output (CO)
Volume of blood ejected by each ventricle per minute
CO = HR x SV
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What can CO increase to during exercise?
Up to 35 L/min
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Heart rate
determined by the rate of depolarization of the SA node
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Myocardial contractility
Force of contraction of the myocardium
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What does the sympathetic nervous system to do myocardial contractility?
It increases contractility, therefore increasing stroke volume
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Otto Frank
Force of contraction is proportional to muscle fiber length
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What is the extent of the effect of the parasympathetic nervous system on myocardial contractility?
It has no effect. Few parasympathetic neurons innervate the ventricles, so it doesn't do anything.
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Ernest Sterling
Working with functional hearts shows that force of contraction is proportional to EDV
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End-diastolic volume (EDV)
1. Increased venous return to the heart leads to increased EDV
2. Increased EDV compensated for by increase in stroke volume
Mechanism is same length-tension relationship as observed in skeletal muscle
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Ejection Fraction
SV/EDV (Remains fairly constant)
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Frank-Starling Law of the Heart
Stroke volume is proportional to EDV
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What are the major resistance vessels?
The arterioles
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Hypoxia
O2 demand exceeds O2 supply
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What is blood flow controlled by?
The sympathetic nervous system circulating epinephrine
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The sympathetic nervous system circulating epinephrine
1. Causes vasoconstriction
2. Increase in venous pressure
3. Increased venous return
4. Increased EDV
5. Increased SV
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Skeletal muscle pump
Leads to increase in venou sreturn
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Respiratory pump
Increases venous return; pressure changes due to breathing
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Baroreceptor Reflex
Mechanism by which blood pressure is being maintained in spite of changes in body position
100
List out the steps of the baroreceptor reflex when you stand up.
1. Stand up
2. Gravity shifts blood to lower limbs
3. Veins expand
4. Decrease in venous return
5. Decrease in cardiac output
6. Decrease in MAP
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Arterial baroreceptors
Sensory receptors; in carotid sinus and aortic arch
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Sensory neurons; carotid sinus nerve
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Cardiovascular center
Control center in medulla
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Efferent pathway
Autonomic motor neurons; vagus nerve
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Hemorrhage
Loss of blood; lowers MAP
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What happens when there is a loss of >20% of blood volume?
You enter circulatory shock
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Circulatory shock
Reduced cardiac output to the extent that tissues are damaged from inadequate blood flow
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What happens when the myocardium does not receive enough blood?
Death
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Hypotension
Low blood pressure (< 100/60 mmHg)
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Postural hypotension
Failure to adjust BP upon standing
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Hypertension
High blood pressure (> 140/90 mmHg); increased work of the heart leads to fatigue, leading to heart failure
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What are the functions of the urinary system?
1. Excretion of metabolic waste
2. regulation of electrolyte balance
3. Control of body water balance
4. Elimination of foreign chemicals
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Kidney
Removes water and waste products from urine; primary function is to regulate the extracellular fluid environment through the production of urine
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Ureter
Drains urine from the kidney
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Urinary bladder
Storage of urine
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Urethra
Elimination of urine
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Nephron
Functional unit of the kidney; about one million in each kidney
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What is a nephron made up of?
A tuft of capillaries and a tubule
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Tubule
Forms a cup shape around the glomerulus called the glomerular capsule (Bowman's capsule)
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Juxtamedullary nephrons
Have a long loop of Henle and are involved in the concentration of urine (~15%)
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Cortical nephrons
Most nephrons; have a short loop of Henle and are for secretion/reabsorption
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Glomerular capillaries
specialized for filtration; only capillaries in the body that are few and drained by an arteriole
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Peritubular capillaries
How most of the filtrate returns to the blood
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Glomerular filtration
Starting point for the production of urine; passage of protein-free plasma from the glomerular capillaries into Bowman's capsule
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What is the mechanism of glomerular filtration?
1. Glomerulus capsule is impermeable to cells and proteins
2. Driving force is hydrostatic pressure in the glomerulus
3. Glomerular capillary BP = 60mmHg
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What is the composition of the filtrate from glomerular filtration?
It is the same a blood plasma minus proteins
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What is the equation for net glomerular filtration pressure?
Pressure (of glomerular capillary) - Pressure (of Bowman's Space) - Osmotic pressure (of glomerular capillary)
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Proteinuria
Blood cells or protein in the urine; signals a problem with the filtration membrane
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Glomerular filtration rate (GFR)
Volume of fluid filtered from the plasma per unit time (120 mL/min = 180 L/day)
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What does determination of GFR rely on?
Clearance of creatine; a ride in blood creatine level is observed only with marked damage to functioning nephrons
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Renal clearance
Volume of blood plasma from which a substance is completely removed per minute
P x CI = U x V
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What are the characteristics of creatine?
1. Freely filtered
2. Not secreted or reabsorbed
3. Amount of creatine excreted in urine = amount of creatine
4. Clearance of creatine = 120 mL/min
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Tubular secretion
Selective transfer of substances from blood into tubular fluid
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What type of substances move from the peritubular capillaries into the tubular lumen?
1. Drugs and drug metabolites
2. Undesired products (urea and uric acid)
3. Excess K+
4. To control blood pH
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Para-aminohippuric acid (PAH)
Totally secreted; clearance of 625 mL/min and is used to measure renal plasma flow
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Penicillin
Antibiotic secreted with high efficiency; results in rapid elimination of penicillin from the body
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Describe the renal circulation, beginning with the renal artery and ending with the renal vein.
Renal artery --> Afferent arterioles --> Glomerular capillaries --> Efferent arterioles --> Peritubular capillaries and/or vasa recta --> Interlobular veins --> Renal vein
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Are Hydrogen ions (H+) secreted at a base rate?
No, they are secreted at a variable rate, as they are important in the regulation of acid-base balance
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What is the normal pH of urine?
6
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How are substances reabsorbed to be conserved?
They are reabsorbed by tubules during tubular secretion
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Is sodium reabsorbed or secreted?
Sodium ions are 99% reabsorbed, as they are the most abundant cation in filtrate
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What is the mechanism for sodium reabsorption?
Primary active transport; it utilizes 80% of the kidney's total energy requirement.
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Where is the majority of sodium reabsorption in the kidney?
The proximal tubule and Loop of Henle
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True or False. A very small percentage of sodium ions are reabsorbed in the descending tubule.
FALSE. There are no sodium ions reabsorbed in the descending tubule
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What does the reabsorption of sodium in the distal tubule depend on?
Aldosterone secretion
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What type of channels allow Na+ reabsorption in the ascending limb?
NKCC channels
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Diuretics
increase urine volume, such as furosemide and Lasix; useful in the treatment of hypertension
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How do diuretics work?
Diuretics force the kidneys to excrete more water and sodium, therefore losing fluid. Once the fluid is released, there is less pressure built up, therefore lowering someone's BP
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True or False. 100% of glucose is reabsorbed.
True
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Glucosuria
Excess glucose is found in urine
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Urea
Product significantly excreted in urine; only about 50% is reabsorbed
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Herman Boerhaave
First discovered urine in 1727
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Friedrich Wohler
Obtained urea by treating silver isocyanate with ammonium chloride; discredited vitalism
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Aldosterone
Hormone secreted by adrenal cortex; stimulates Na+ reabsorption and is stimulated by angiotension II
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Renin-angiotensin system
uxtaglomerular apparatus; JG cells in afferent arteriole secrete the enzyme renin into the blood
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What are the stimuli to renin secretion?
1. JG cells serve as stretch receptors
2. Decreased renal arteriolar pressure
3. Decreased distal tubular Na+
4. Stimulation of renal sympathetic nerves
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Angiotensin II
Potent stimulator of aldosterone secretion
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Renin-Angiotensin-Aldosterone System (RAAS)
part of a complex feedback circuit that functions in homeostasis
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Urine Concentrating mechanism
Water intake must equal water output in order to maintain body water balance
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What is the function of the collecting duct?
To concentrate the urine by reabsorbing water
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What is the countercurrent mechanism?
1. Descending loop of Henle is relatively impermeable to solutes and freely permeable to water
2. Ascending limb is permeable to solutes not water
3. Ascending limb active transports from ions into the interstitial fluid
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Vasa Recta
Structural vessel; maintains the concentration gradient in the medullary fluid and helps to maintain blood osmolarity
163
What does the reabsorption of water from the collecting duct depend on?
Antidiuretic hormone
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What is the mechanism of vasopression?
It causes insertion of aquaporins into the membrane of the collecting duct cells
165
Micturition Reflex
1. Bladder wall contains stretch receptors
2. When stretched, signals to lower spinal cord
3. Activates parasympathetic neurons going to the bladder and urethra
4. Bladder wall contracts involuntarily and internal sphincter relaxes
5. Can be prevented by voluntarily contracting the external urethral sphincter
6. Relax external sphincter
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Urinary incontinence
Inability to control urination
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What are some reasons of urinary incontinence?
Infants, SCI, and being elderly
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Kidney stones
Formation of calcium crystals in renal pelvis
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Renal failure
Damage to kidneys so that glomeruli fail to filter the blood
170
What are some causes of renal failure?
1. Infection (nephritis)
2. Inadequate blood flow
3. Obstruction of urinary tract
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What are some consequences of renal failure?
1. Decreased GFR
2. Proteinuria
3. Uremia
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Uremia
Toxic substances in blood
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How can renal failure be treated?
1. Renal dialysis
2. Kidney transplant
