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Physio 202 Lecture > Lecture 33 Unit 5 > Flashcards

Lecture 33 Unit 5 Flashcards

1
Q

what is the formula for rate of excretion

A

rate of glomerular filtration+rate of secretion - rate of reabsorption

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2
Q

what produces glomerular filtrate

A

blood pressure

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3
Q

how much filtrate is reabsorbed per day to form how much urine per day

A

180 liters/day of filtrate to form 1-2 liters/day of urine

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4
Q

what is filtering capacity enhanced by

A
  • thinness of membrane
  • large surface area of glomerular capillaries
  • high glomerular capillary blood pressure
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5
Q

what does the filtration barrier consist of

A
  • fenestration of glomerular endothelial cell
  • basal lamina of glomerulus
  • slit membrane between pedicels
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6
Q

what do fenestrations of glomerular epithelial cells do

A

prevents filtration of blood cells but allows all components of blood plasma to pass through

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7
Q

what does the basal lamina of glomerulus do

A

prevents filtration of larger proteins

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8
Q

what does the slit membrane between pedicels do

A

prevents filtration of medium sized proteins

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9
Q

what are macula densa cells and where are they located

A

top of ascending limb and they interact with cells lining the afferent arteriole

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10
Q

what is the thickened part of the ascending limb

A

macula densa

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11
Q

what is the net filtration pressure in the nephron

A

10 mmHg

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12
Q

what is the glomerular blood hydrostatic pressure

A

55 mmHg

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13
Q

what is the capsular hydrostatic pressure

A

15 mmHg

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14
Q

what is the blood colloid osmotic pressure

A

30 mmHg

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15
Q

what is the amount of filtrate formed in all renal corpuscles of both kidneys per minute

A

125 mL/min

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16
Q

what happens when GFR is too high

A

useful substances are lost due to the speed of fluid passage through nephron

17
Q

what happens when GFR is too low

A

sufficient waste products may not be removed from the body

18
Q

what is the formula for NFP

A

GBHP-CHP-BCOP

19
Q

what is required to maintain homeostasis

A

constant GFR

20
Q

what does NFP depend most heavily on

A

GBHP

21
Q

when does filtration stop

A

if GBHP drops from 55mmHg to 45 mmHg

22
Q

what is GBHP determined by

A

MAP

23
Q

what mean arterial pressure do kidneys normally function with

A

80mmHg and 180 mmHg

24
Q

what is auto regulation of GFR

A

mechanisms that maintain a constant GFR despite changes in arterial blood pressure

25
Q

what are the mechanisms in auto regulation of GFR

A
  • myogenic mechanism

- tubuloglomerular feedback

26
Q

which mechanism of auto regulation is faster

A

myogenic

27
Q

what happens in myogenic mechanism

A
  • systemic increases in blood pressure stretch the afferent arteriole
  • smooth muscle contraction reduced the diameter of the afferent arteriole returning the GFR to its previous level in seconds
28
Q

what happens in tubuloglomerular feedback

A
  • elev Aten systemic blood pressure raises the GFR so that fluid flows too rapidly through the renal tubule, Na+ and Cl- are not reabsorbed
  • macula densa in ascending limb of loop of henle detects increased Na+ and Cl- which inhibits release of nitric oxide from juxtaglomerular apparatus
  • afferent arteriole constrict which reduces GFR
29
Q

what happens in neural regulation of GFR

A
  • blood vessels of the kidney are supplied by sympathetic fibers that cause vasoconstriction of afferent arterioles
  • SNS will override renal autoregulation
  • SNS will also stimulate renin release from the juxtaglomerular cells
30
Q

in neural regulation what happens with no SNS activity

A

blood vessels are maximally dilated

31
Q

in neural regulation what happens with moderate SNS

A

bother afferent and efferent arterioles constrict equally

32
Q

in neural regulation what happens with extreme sympathetic stimujlation

A

vasoconstriction of afferent arteriole predominates

33
Q

what happens with extreme SNS

A
  • GFR decreases substantially
  • lowers urine output to maintain blood volume
  • permits greater blood flow to other tissues
34
Q

what are the two hormones that contribute to regulation of GFR

A

atrial natriuretic peptide and angiotensin II

35
Q

what does ANP do

A

increases GFR

36
Q

how does ANP increase GFR

A
  • stretching of the atria that occurs with an increase in blood volume causes hormonal release
  • relaxes glomerular mesangial cells increasing glomerular capillary surface area
37
Q

what does angiotensin II do

A

reduce GFR

38
Q

how does Angiotensin II reduce GFR

A
  • activated by ACE in the lungs following the release of renin from juxtaglomerular cells
  • potent vasoconstrictor that narrow both afferent and efferent arterioles reducing GFR

Physio 202 Lecture (38 decks)

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