Lecture 17: Renal Physiology Flashcards

1
Q

if RBF is too low, the afferent arteriole:

A

relaxes

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2
Q

if RBF is too high, the afferent arteriole:

A

constricts

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3
Q

this vessel is primarily responsible for autoregulation of renal blood flow

A

afferent arteriole

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4
Q

this vessel is primarily responsible for fine-tuning GFR

A

efferent arteriole

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5
Q

what effect does increasing afferent arteriole resistance have on glomerular pressure?

A

decreased glomerular pressure

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6
Q

what effect does decreasing glomerular presure have on GFR?

A

decreased GFR

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7
Q

what effect does increasing afferent arteriole resistance have on renal blood flow?

A

decreased renal blood flow

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8
Q

what effect does decreased renal blood flow have on GFR?

A

decreased GFR

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9
Q

what effect does increasing efferent arteriole resistance have on glomerular pressure?

A

increasing glomerular pressure

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10
Q

what effect does increasing glomerular pressure have on GFR?

A

increased GFR

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11
Q

what effect does increasing efferent arteriole resistance have on renal blood flow?

A

decreased renal blood flow

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12
Q

what effect does increased glomerular pressure have on GFR?

A

increased GFR

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13
Q

what would cause a decreased renal blood flow?

A
  1. increased afferent arteriole resistance
  2. increased efferent arteriole resistance
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14
Q

what effect would dilation of the afferent arteriole have on GFR?

A

dilation of afferent > increased glomerular pressure > increased GFR

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15
Q

what effect would dilation of the efferent arteriole have on GFR?

A

dilation of efferent arteriole > decreased glomerular pressure > decreased GFR

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16
Q

what might cause impediment of arterial dilation?

A
  • being sick/critically ill
  • chronic hypertension
  • uncontrolled diabetes
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17
Q

GFR autoregulation is dependent on

A

renal blood flow autoregulation

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18
Q

GFR is better regulated at higher or lower blood pressures?

A

higher; at pressures of 50 mmHg or lower, GFR has a steeper decline than when BP is closer to 150 mmHg or higher (a more shallow, flatter slope)

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19
Q

GFR autoregulation at high pressures prevents the kidneys from:

A

spilling massive amounts of fluid into the urine

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20
Q

the normal UOP rate

A

1 ml/min

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21
Q

as MAP increases, UOP:

A

increases

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22
Q

as MAP decreases, UOP:

A

decreases

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23
Q

if GFR is increased, UOP ____ and blood pressure _____

A
  1. increases
  2. decreases
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24
Q

if GFR is decreased, UOP ____ and blood pressure _____

A
  1. decreases
  2. increases
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25
Q

filtration only:

A

some substances are completely reabsorbed

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26
Q

filtration with partial reabsorption:

A

some substances are partially reabsorbed
ex) Na+

excessive Na+ in our diet gets partially reabsorbed

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27
Q

filtration with complete reabsorption:

A

some substances are filtered and secreted
ex) glucose (in a NON-DM patient)
normally, ALL of the glucose gets COMPLETELY reabsorbed in the PCT

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28
Q

filtration with secretion

A

some substances are filtered and neither reabsorbed or secreted
ex) paramino hippuric acid (PAH)

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29
Q

in filtration with secretion, how much substance gets filtered and how much gets secreted?

A
  1. 1/5 gets filtered
  2. 4/5 gets secreted
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30
Q

what is PAH and why is it used?

A

paramino hippuric acid
it is used as a diagnostic compound to measure renal blood flow by observing how much of the compound is cleared by the kidneys

the more PAH that is cleared by the kidneys, the higher the RBF is
the less PAH that is cleared by the kidneys, the lower the RBF is

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31
Q

what is the normal reabsorption rate?

A

124 ml/min

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32
Q

urinary excretion = ?

A

filtration - reabsorption + secretion

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33
Q

NFP = ?

A

Pcap - Pisf - Picap + Piisf

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34
Q

what is the innermost layer of the glomerular capillaries?

A

endothelium

these are MORE permeable than generic capillaries

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35
Q

the porous openings in the glomerular capillary endothelium

A

fenestrations

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36
Q

the layer superficial to glomerular endothelium capillaries

A

basement membrane

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37
Q

what is the purpose of the epithelium in glomerular capillaries?

A

houses podocytes which provide structural support; the capillary beds resist a lot of increased pressure and the podocytes provides structural support to prevent glomerular swelling

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38
Q

the podocytes have foot processes that have openings called:

A

split pores

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39
Q

the glomerular capillaries have a (positive/negative) charge within membrane

A

negative

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40
Q

what is the benefit to having negative charges scattered within the glomerular capillary?

A

to repel negatively charged proteins

41
Q

describe the role of renal podocytes

A
  1. to provide structural support to the glomerular capillaries
  2. to prevent glomerular swelling (with structural support) d/t high BP
  3. to regulate surface area of glomerular capillaries
42
Q

what is dextran?

A

a synthetic sugar that is modifiable in compound size

43
Q

polycationic dextran is (more/less) filterable

A

more filterable

44
Q

polyanionic dextran is (more/less) filterable

A

less

45
Q

the larger a compound is, the _____ filterable it is

A

less

46
Q

what is inulin?

A

a synthetic compound used to accurate way to estimate GFR (similar to creatinine clearance)

47
Q

a filterability of 1.0 =

A

high filterability

i.e. H2O

48
Q

a filterability of .005 =

A

a low filterability

i.e. albumin

49
Q

roles of the kidney include (9)

A
  1. LT BP regulation
  2. LT pH regulation
  3. LT [RBC] regulation
  4. LT [electrolyte] regulation
  5. LT vitamin D regulation
  6. LT serum glucose regulation
  7. drug clearance
  8. LT metabolic waste disposal
  9. osmolarity regulation

all these roles are accomplished with a normal GFR

50
Q

chronic HTN is a ____ issue

A

kidney

51
Q

how does the kidney regulate pH levels?

A
  1. the kidneys produce HCO3-
  2. the kidneys control how much HCO3- gets reabsorbed
  3. the kidney can get rid of excess protons (H+)
52
Q

what is the short-term pH regulator of the body?

A

the lungs - can blow off excess CO2 (but not H+ directly)

53
Q

how does the kidney regulate [RBC] levels?

A
  • O2 sensors deep in medullary portions of kidney
  • low O2 levels > stimulates bone marrow > to produce erythryopoietin (epo) > increase more RBCs
  • RBCs will travel to wherever O2 is needed and transport O2 there
54
Q

how does the kidney regulate vitamin D levels?

A
  • the kidney activates vitamin D
  • activated vitamin D helps the kidney reabsorb Ca2+
55
Q

the more glucose that is filtered, the ____ that is reabsorbed

A

more

56
Q

if serum glucose is past transport max of the kidney, what happens to the glucose?

A

in extreme hyperglycmia, glucose gets lost/”skimmed off” via excretion in the urine

57
Q

drug clearance occurs mostly in the:

A

liver
some clearance occurs via the kidney

58
Q

how does the kidney regulate osmolarity?

A
  • the kidney is able to differentiate water from NaCl, so it can selectively reabsorb water
  • the kidney can also get rid of excess NaCl
  • this process is regulated by ADH and osmoreceptors in the BRAIN
59
Q

delineate the circulation flow from renal artery to renal vein

A
  1. renal artery
  2. segmental arteries
  3. interlobar arteries
  4. arcuate arteries
  5. interlobular arteries
  6. aferrent arteriole
  7. glomerular capillaries
  8. efferent arteriole
  9. peritubular capillaries
  10. arcuate veins
  11. interlobar veins
  12. segmental veins
  13. renal vein
60
Q

which structures make up a nephron?

A
  • afferent arterioles
  • glomerular capillaries
  • efferent arterioles
  • peritubular capillaries

PLUS tubular network:
* PCT
* DCT
* Loop of Henle
* cortical collecting tubule
* collecting duct

61
Q

each KIDNEY has how many nephrons at birth?

A

1 million

62
Q

at birth how many nephrons do we have?

A

2 million

63
Q

at what age do we start to lose nephrons (d/t “wear & tear”)

A

40 yrs old

64
Q

superficial nephrons AKA

A

cortical nephrons

65
Q

deep nephrons AKA

A

inner medullary nephrons

66
Q

what percentage of our nephrons are cortical?

A

90-95%

67
Q

what percentage of our nephrons are inner medullary?

A

5-10%

68
Q

there are fewer peritubular capillaries in the (outer medulla/inner medulla)?

A

inner medulla

69
Q

the outer medulla’s peritubular capillaries reabsorb compunds from:

A

the cortical nephrons

70
Q

between ascending & descending blood vessels in the inner medulla, there are more of the:

A

ascending blood vessels

71
Q

why are there more ascending blood vessels in the inner medulla?

A

there are more split points in the ascending blood vessels

72
Q

why is it important to have “split points” in the ascending blood vessels in the inner medulla?

A
  • more split points will cause a decreased blood flow velocity in the ascending blood vessels
  • this is important to maintain solute concentration in the interstitium of the inner medulla
  • decreased blood flow velocity in the ascending blood vessels prevents “wash out” of solutes
73
Q

concentrated solutes in the renal interstitium is beneficial for the process of

A

reabsorption
accomplished with the help of decreased blood flow velocity in ascending blood vessels

74
Q

deep/inner medullary peritubular capillaries AKA

A

vasa recta capillaries

75
Q

which type of nephron is more sensitive to low perfusion in terms of oxygen delivery?

A
  • deep medullary nephrons d/t there only being 5-10% of this type of nephron vs cortical nephrons
  • there is a limited supply of peritubular capillaries located in the deep medulla

PT capillaries play a large role in reabsorption AND O2 delivery

76
Q

kidneys lie underneath the

A

diaphragm

77
Q

renal artery and vein lie deep to the

A

mesenteric arteries

78
Q

which arteries supply blood to the intestines?

A

mesenteric arteries

79
Q

how many adrenal glands do we have?

A

2

1 adrenal gland lies on top of each kidney

80
Q

how many ureters do we have?

A

2

81
Q

suprarenal glands AKA:

A

adrenal gland

supra = above; above renal

82
Q

this kidney comes into contact with the liver

A

RIGHT kidney

the liver is on the right side

83
Q

this kidney comes into contact with the stomach, spleen, and the pancreas

A

LEFT kidney

84
Q

which kidney comes into contact with the colon?

A

both

85
Q

relate renal surface anatomy to cancer

A
  • kidney cancer is RARE
  • surface area contact with other organs is important in terms of cancer spreading to the kidney (i.e. pancreatic cancer will spread to the middle of the LEFT kidney)
86
Q

why is renal cancer rare?

A
  • the kidneys do not produce new nephrons
  • since there is no cell proliferation, the risk of renal cancer is rare

heart CA is also rare

87
Q

which quadranst of the abdomen do the kidneys lie?

A

RUQ - R kidney
LUQ - L kidney

88
Q

kidney stones exhibit this type of pain

A

referred pain in the lower back

89
Q

the urethra is shorter in:

A

females

90
Q

the pudendal nerve originates from these spinal nerves

A

S2, S3, & S4

S 2-3-4 keeps things off the floor

91
Q

pudendal nerve functions (3)

A
  • bladder emptying
  • fecal waste emptying
  • boners
92
Q

prostate gland removal increases risk for:

A
  • erectile dysfunction
  • incontinence
93
Q

corpuscle AKA:

A

bowman’s capsule

94
Q

which part of the Loop of Henle is thick? thin?

A

TAL - thick ascending limb
DTL/ATL - descending thin limb AND ascending thin limb

95
Q

the macula densa lies in:

A

TAL (thick ascending limb)

96
Q

what do the macula densa cells do?

A
  • “speedometer” of the blood flow/filtration rate
  • if low flow is sensed, communicates with juxtaglomerular cells
97
Q

what do the juxtaglomerula cells do?

A
  • releases renin to preferentially relax/constrict the efferent arteriole
98
Q

if low flow is sensed by MD cells, what happens?

A
  • JG cells release RENIN
  • renin releases AT II to **preferentially **constrict EA
  • constricted EA > decreased RBF > occludes outflow from GCs
  • GCs hydrostatic pressure increases
  • increased GC pressure > increased filtration rate
99
Q

if high flow is sensed by MD cells, what happens?

A
  • JG cells restrict RENIN release
  • EA dilates > increases RBF
  • GCs hydrostatic pressure decreases
  • decreased GC pressure > decreased filtration rate