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Physiology 202 > Unit 5 Lecture 33 > Flashcards

Unit 5 Lecture 33 Flashcards

1
Q

Define glomerular filtration

A

portion of glomerular blood PLASMA is filtered into capsular space

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2
Q

Define tubular reabsorption

A

water and useful substances are reabsorbed into blood from tubular fluid

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3
Q

Define tubular secretion

A

certain wastes are removed from blood by secretion into tubular fluid (soon to be called URINE)

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4
Q

function of collecting ducts

A

reabsorption and secretion

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5
Q

Define excretion

A

eliminating waste from body

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6
Q

Formula for rate of excretion

A

Rate of filtration, plus rate of secretion, minus rate of reabsorption

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7
Q

What causes filtration to occur and what percent becomes filtrate?

A

blood pressure –> ~20% filtrate

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8
Q

What increases % filtration?

A
  • thin membrane
  • large surface area of glomerular capillaries
  • high glomerular capillary blood pressure (bc SMALL SIZE OF EFFERERNT ARTERIOLE)
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9
Q

What are the 3 filtration barrier layers that make up the glomerular capillaries?

A
  1. fenestrations (pores)of endothelial cells
  2. basal lamina
  3. slit membrane
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10
Q

What do fenestrations prevent and allow from being filtered into nephron

A

prevents: blood cells
allows: components of blood plasma

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11
Q

What does the basal lamina prevent being filtered?

A

larger proteins

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12
Q

What does the slit membrane prevent being filtered?

A

medium sized proteins

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13
Q

What type of cells are found within the top of the ascending limb of loop Henle

A

Macula densa cells

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14
Q

What do the macula densa cells interact with?

A

juxtaglomerular cells in afferent arteriole lining

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15
Q

Define net filtration pressure

A

The pressure that allows water and small solutes to pass through the renal corpuscle

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16
Q

What is the largest contributor to NFP?

A

glomerular blood hydrostatic pressure

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17
Q

Define glomerular blood hydrostatic pressure

A

The pressure that pushes plasma filtrate from glomerular capilalries into capsular space

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18
Q

What changes the glomerular blood hydrostatic pressure?

A

afferent and efferent arterioles

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19
Q

Define capsular hydrostatic pressure

A

the MECHANICAL pressure from the glomerular capsule pushing back on the filtrate coming out of the glomerular capillaries

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20
Q

Define blood colloid osmotic pressure

A

the force caused by differences in WATER CONCENTRATION GRADIENT that pulls water from filtrate back into plasma in glomerular capillaries because nutrients/ proteins were not able to be filtered through capillaries

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21
Q

Formula for NFP

A

= GBHP - (CHP + COP)

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22
Q

What is the normal NFP?

A

10 mmHg

23
Q

Define glomerular filtration rate

A

the amount of filtrate formed in all renal corpuscles of both kidneys / minute

24
Q

What is the average GFR?

A

125 mL/min

25
Q

What happens if GFR is too high?

A

useful substances are lost bc speed of fluid passage through nephron

26
Q

What happens if GFR is too low?

A

sufficient waste products may not be removed from the body

27
Q

What determines if GFR is consistent?

A

a consistent NFP

28
Q

What is NFP reliant on?

A

GBHP

29
Q

What determines GBHP?

A

Mean arterial pressure (MAP)

30
Q

What is the normal range of MAP?

A

80-180 mmHg

31
Q

What are the 3 ways that GFR is regulated?

A
  1. Autoregulation
  2. Neural regulation
  3. Hormonal regulation
32
Q

What is autoregulation of GFR?

A

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

33
Q

What two things perform autoregulation of GFR?

A
  1. Myogenic mechanism

2. tubuloglomerular feedback

34
Q

What happens during myogenic mechanism (fast)?

A

When increased blood pressure stretches efferent arteriole, smooth muscle (MYO*genic) contracts the afferent arteriole diameter to restore GFR level

35
Q

What happens during tubuloglomerular feedback (slower)?

A
  • Increased blood pressure increases BFR which causes blood to flow fast through renal tubule –> Na+ and Cl- aren’t reabsorbed (stays in urine)
  • Macula densa in ascending limb of Henle detects Na+ and Cl- –> inhibits release of Nitric Oxide (vasodilator) from juxtaglomerular apparatus
  • afferent arterioles constrict –> reduced GFR
36
Q

What system is the neural regulation of GFR controlled by?

A

sympathetic nervous system

37
Q

What are the blood vessels of the kidneys supplied by?

A

sympathetic fibers

38
Q

What do the sympathetic fibers do to afferent arterioles?

A

vasoconstrict arterioles

39
Q

What specifically is released by sympathetic postganglionic neurons that causes vasoconstriction?

A

NE

40
Q

What does NE bind to to cause vasoconstriction?

A

alpha 1 adrenergic receptors

41
Q

Besides from NE, what else does the SNS release and from where?

A

Renin from juxtaglomerular cells

42
Q

What happens to renal blood vessel diameter with minimal sympathetic activity?

A

blood vessel diameter is maximally dilated

43
Q

What regulation prevails with max dilation and minimal SNS activity

A

renal autoregulation

44
Q

What happens to blood vessel diameter with moderate SNS stimulation?

A

Afferent and efferent arterioles constrict equally

45
Q

What happens to GFR during moderate SNS activity and moderate constriction of arterioles?

A

GFR decreases slightly

46
Q

What happens to blood vessel diameter with extreme SNS stimulation?

A

vasoconstriction of AFFERENT arterioles predominates

47
Q

What happens to GFR, urine output, and blood flow to other tissues during extreme SNS activity and vasoconstriction of afferent arterioles

A
  • GFR decreases substantially
  • lowers urine output to maintain blood volume
  • permits greater blood flow to other tissues (ie muscles)
48
Q

What two hormones regulate GFR?

A
  1. Atrial Natriuretic Peptide (ANP)

2. Angiotensin II

49
Q

Atrial Natriuretic Peptide does what to GFR?

A

INCREASES GFR

50
Q

Angiotensin II does what to GFR?

A

DECEASES GFR

51
Q

How does ANP get released?

A

Increased blood volume stretches the atria which releases ANP

52
Q

How does ANP increase GFR?

A

It relaxes glomerular mesangial cells increasing glomerular capillary surface area –> increased GFR

53
Q

How does angiotensin II get released?

A

it’s activated by ACE (angiotensin converting enzyme) in lungs following the release of renin from juxtaglomerular cells

54
Q

How does angiotensin II decrease GFR?

A

it’s a vasoconstrictor that narrows both afferent and efferent arterioles reducing GFR

Physiology 202 (43 decks)

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