Chapter 26 - Guyton (2nd EXAM)

Question 1

Functions of the kidneys.

Answer 1

• Excretion of metabolic waste products and foreign chemicals
• Regulation of water and electrolyte balances
• Regulation of body fluid osmolality and electrolyte concentrations
• Regulation of arterial pressure
• Regulation of acid-base balance
• Secretion, metabolism, and excretion of hormones
• Gluconeogenesis

Question 2

In people with severe kidney disease or who have had their kidneys removed and have been placed on hemodialysis, severe anemia develops as a result of?

Answer 2

decreased erythropoietin production

Question 3

How do the kidneys contribute to normal calcium deposition in bone and calcium reabsorption by the gastrointestinal tract?

Answer 3

kidneys produce the active form of vitamin D, 1,25-dihydroxyvitamin D3 (calcitriol)

Question 4

The kidneys synthesize glucose from amino acids and other precursors during prolonged fasting, a process referred to as?

Answer 4

gluconeogenesis

Question 5

Are the kidneys located inside or outside the peritoneal cavity?

Answer 5

outside

Question 6

The renal artery and ureter pass through what?

Answer 6

hilium

Question 7

Blood flow to the kidneys is about how much of the cardiac output?

Answer 7

22% (or about 1100 mL/min)

Question 8

Located between the glomerular and peritubular capillaries, this structure helps regulate hydrostatic pressure in both sets of capillaries.

Answer 8

efferent arterioles

Question 9

Each nephron contains?

Answer 9

a tuft of glomerular capillaries called the glomerulus, through which large amounts of fluid are filtered from the blood, and a long tubule in which the filtered fluid is converted into urine on its way to the pelvis of the kidney

Question 10

Bowman’s capsule

Answer 10

encases one glomerulus

Question 11

Efferent arteriole

Answer 11

leads to a second capillary network, the peritubular capillaries

Question 12

Afferent arterioles

Answer 12

lead to the glomerular capillaries, where large amounts of fluid and solutes (except the plasma proteins) are filtered to begin urine formation

Question 13

Micturition

Answer 13

process by which the urinary bladder empties when it becomes filled

Question 14

Contraction of the _______ muscle is a major step in emptying the bladder.

Answer 14

detrusor

Question 15

Principal nerve supply to the bladder.

Answer 15

pelvic nerves, which connect with the spinal cord through the sacral plexus, S-2 and S-3 (sensory and motor - parasympathetic); skeletal motor fibers transmitted through the pudendal nerve to the external bladder sphincter; sympathetic innervation
through the hypogastric nerves, connecting mainly with L-2

Question 16

Peristaltic contractions in the ureter are enhanced by ___________ stimulation and inhibited by ___________ stimulation.

Answer 16

parasympathetic; sympathetic

Question 17

The ureters enter the bladder through the detrusor

muscle in the _______ region of the bladder.

Answer 17

trigone

Question 18

Vesicoureteral reflux

Answer 18

urine in the bladder is propelled backward into the ureter

Question 19

This effect is important for preventing excessive flow of fluid into the pelvis of a kidney with a blocked ureter (stone).

Answer 19

ureterorenal reflex (pain impulses cause a sympathetic reflex back to the kidney to constrict the renal arterioles, thereby decreasing urine output from the kidney)

Question 20

Stretch signals from the _______ ______ are especially strong and are mainly responsible for initiating the reflexes that cause bladder emptying.

Answer 20

posterior urethra

Question 21

What nerves must be inhibited to cause urination even when you don’t want to?

Answer 21

pudendal nerves to external sphincter (micturition reflex becomes powerful enough it will inhibit voluntary constrictor signals)

Question 22

The micturition reflex is a completely autonomic spinal cord reflex, but it can be inhibited or facilitated by centers in the brain. These centers include:

Answer 22

strong facilitative and inhibitory centers in the brain stem, located mainly in the pons, and several centers located in the cerebral cortex

Question 23

What is the cause of overflow incontinence?

Answer 23

damaged sensory fibers from the bladder to the spinal cord preventing stretch signals so urine constantly overflows a few drops at a time into urethra (despite intact efferent fibers from the cord to the bladder and despite intact neurogenic connections within the brain); this would be caused by injury at the sacral region of the spinal cord

Question 24

How is micturition affected by spinal cord injury above the sacral region?

Answer 24

typical micturition reflexes can still occur but no longer controlled by the brain; periodic (unannounced) bladder emptying

Question 25

Uninhibited neurogenic bladder.

Answer 25

condition derives from partial damage in the spinal cord or the brain stem that interrupts most of the inhibitory signals; facilitative impulses passing continually down the cord keep the sacral centers so excitable that even a small quantity of urine elicits an uncontrollable micturition reflex (frequent urination)

Question 26

Urinary excretion rate =

Answer 26

filtration - reabsorption + secretion

Question 27

What are two advantages to a high GFR?

Answer 27

some waste products depend primarily on glomerular filtration for their excretion, entire plasma can be filtered and processed about 60 times each day

Question 28

Urine formation begins with filtration of large amounts of fluid through the glomerular capillaries into ________ ________.

Answer 28

Bowman’s capsule

Question 29

GFR is determined by:

Answer 29

sum of the hydrostatic and colloid osmotic forces across the glomerular membrane, which gives the net filtration pressure; and glomerular capillary filtration coefficient Kf (GFR = Kf x Net filtration pressure)

Question 30

The glomerular capillaries have a much higher rate of filtration than most other capillaries because?

Answer 30

high glomerular hydrostatic pressure and a large Kf

Question 31

What prevents plasma proteins from passing through the fenestrations in the glomerular capillary membrane?

Answer 31

endothelial cells, basement membrane, and epithelial cells all have a fixed negative charge (proteoglycans) that prevents the passage of plasma proteins

Question 32

Kf =

Answer 32

GFR / net filtration pressure

Question 33

In what ways does chronic hypertension and uncontrolled diabetes mellitus reduce Kf?

Answer 33

increasing the thickness of the glomerular capillary basement membrane and damaging the capillaries so severely that there is loss of capillary function

Question 34

Bowman’s capsule hydrostatic pressure typically does not change (if it increases, GFR will decrease). What could increase Bowman’s capsule hydrostatic pressure - most commonly?

Answer 34

precipitation of calcium or uric acid in the ureter (stones)

Question 35

Glomerular hydrostatic pressure is determined by three variables:

Answer 35

arterial pressure, afferent arteriolar resistance, and efferent arteriolar resistance

Question 36

How would constriction of afferent arterioles affect GFR?

Answer 36

decrease

Question 37

How would efferent arteriole constriction affect GFR?

Answer 37

depends on the severity of the constriction; modest efferent constriction raises GFR, but severe efferent constriction (more than a threefold increase in resistance) tends to reduce GFR due to increase in colloid osmotic pressure caused by the Donnan effect

Question 38

Primary determining factor of oxygen consumption in the kidneys?

Answer 38

sodium reabsorption

Question 39

The outer part of the kidney, the renal ______, receives most of the kidney’s blood flow.

Answer 39

cortex

Question 40

Flow to the renal medulla is supplied by a specialized portion of the peritubular capillary system called the ____ _____.

Answer 40

vasa recta

Question 41

Sympathetic nervous system action ________ GFR.

Answer 41

decreases (only when severe as with hemorrhage)

Question 42

Hormones that decrease GFR?

Answer 42

norepinephrine, epinephrine, endothelin, angiotensin II (prevents decrease)

Question 43

Hormones that increase GFR?

Answer 43

endothelial-derived nitric oxide, prostaglandins, bradykinin

Question 44

Adaptive mechanisms in the renal tubules allow them to increase their reabsorption rate when GFR rises, a phenomenon referred to as_____________ balance.

Answer 44

glomerulotubular

Question 45

Decreased macula densa sodium chloride causes?

Answer 45

dilation of afferent arterioles to decrease resistance to blood flow which raises glomerular hydrostatic pressure and helps return GFR toward normal, and increases renin release from the juxtaglomerular cells of the afferent and efferent arterioles (angiotensin II constricts efferent arterioles)

Question 46

How would high protein intake and increased blood glucose affect renal blood flow and GFR?

Answer 46

increase (reabsorbed along with sodium in the proximal tubule)

Question 47

What occurs after GFR drops (tubuloglomerular feedback)?

Answer 47

decreased delivery of sodium chloride to the macula densa activates a tubuloglomerular feedback–mediated dilation of the afferent arterioles and subsequent increases in renal blood flow and GFR

Question 48

Located in the medulla of the kidney?

Answer 48

loop of Henle (juxtamedullary nephrons have a loop of Henle that extends deep into the medulla), medullary collecting tubule, collecting duct

Question 49

Urea

Answer 49

waste product from protein/amino acid metabolism

Question 50

Uric acid

Answer 50

waste product from nucleic acid metabolism

Question 51

Creatinine

Answer 51

waste product from muscle metabolism

Question 52

Bilirubin

Answer 52

waste product from hemoglobin metabolism