Renal Mod 1 Flashcards

1
Q

2 capsules of the kidney

A
  1. renal capsule - surrounds each kidney

2. renal fascia - surrounds kidney and fatty mass

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2
Q

list the gross anatomy of the kidneys

A
  1. capsules
  2. cortex
  3. medulla
  4. renal pyramid
  5. minor calyces
  6. major calyces
  7. renal pelvis
  8. ureter
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3
Q

what does the cortex include

A
  1. glomeruli

2. proximal and distal portions of tubules

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4
Q

what is the medulla of the kidneys

A

straight segments of proximal and distal tubules

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5
Q

what is the renal pyramid

A

functional arrangement for collection

-includes the renal papilla

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6
Q

what is the renal papilla

A

the apex of the pyramid which drains into the minor calyces

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7
Q

what are minor calyces

A

collect urine from renal pyramids

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8
Q

what are the major calyces

A

collect urine from 2-3 minor calyces

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9
Q

what is the renal pelvis

A
  1. collects urine from major calyces

2. funnel shaped duct that becomes continuous with the ureter

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10
Q

what is the ureter

A

smooth muscle tube

drains urine from renal pelvis and descends to the bladder

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11
Q

how long is the ureter

A

25-35cm long

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12
Q

three regions of constriction of the ureter

A
  1. junction of renal pelvis and ureter (ureteropelvic junction)
  2. as ureter passes over pelvic brim
  3. as the ureter enters the bladder
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13
Q

clinical importance of ureter constriction regions

A

potential for kidney stones to be lodged

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14
Q

what facilitates flow of urine into the bladder

A

the smooth muscle that the calyces, renal pelvis and ureteres all contain

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15
Q

each lobe of the kidney has?

A

pyramid and cortex surrounding the pyramid

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16
Q

what is a nephron

A

functional unit of the kidney for formation of urine

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17
Q

how many nephrons do kidneys have

A

1.2 million per kidney

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18
Q

types of nephrons

A
  1. superficial cortical nephrons (85% of total nephrons) - extend partially into the medulla
  2. mid-cortical nephron - short and long loops
  3. juxtamedullary nephron - (12% of total nephrons) - extend deep into medulla
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19
Q

which type of nephron is responsible for urine concentration

A

juxtamedullary nephrons

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20
Q

regions of the nephron

A
  1. renal corpuscle
  2. PCT
  3. Loop of Henle
  4. DCT
  5. Collecting duct
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21
Q

function of renal corpuscle

A

site of filtration

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22
Q

renal corpuscle is formed by?

A

glomerulus
Bowman’s capsule
mesangial cells

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23
Q

what is the function of glomerulus

A

site of capillary filtration

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24
Q

what is the glomerulus formed by?

A

glomberular capillaries that extend into Bownman’s capsule

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25
Q

what is the glomeruluar filtration membrane

A

capillary wall

serves as filtration

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26
Q

three layers of glomerular filtration membrane

A
  1. capillary endothelium - fenestrated capillary wall
  2. basement membrane - negative charge which plays role in filtration
  3. capillary epithelium - foot like projections that form matrix of filtration slits
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27
Q

another name for capillary epithelium

A

podocytes

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28
Q

blood supply to the glomerulus

A
  1. afferent arteriole
  2. efferent arteriole
  3. juxtaglomerular apparatus (JGA)
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29
Q

function of afferent arteriole

A

regulated flow of blood into glomerulus to optimize filtration

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30
Q

function of efferent arteriole

A

glomerulus capillaries drain into efferent arteriole

-blood then travels to peritubular capillaries

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31
Q

importance of blood flowing from efferent arteriole to peritubular capillaries

A

allows reabsorption and secretion along the tubules of the nephrons

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32
Q

what makes up the JGA

A

juxtaglomerular cells + macula densa

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33
Q

where are juxtaglomerular cells located

A

adjacent to afferent glomerular arteriole

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34
Q

what is the macula densa

A
  • cells in distal convoluted tubule located adjacent to afferent and efferent glomerular arterioles
  • macula densa cells function as sodium-chloride receptors
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35
Q

JGA regulates what?

A

renal blood flow
glomerular filtration
renin secretion

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36
Q

what are mesangial cells

A

matrix of smooth muscle and phagocytic cells
located bw glomerular capillaries and Bowman’s capsule
functional role in regulating filtration

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37
Q

what is the Bowman’s capsule

A

collects filtrate from glomerular capillaries

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38
Q

what is the space inside the Bowman’s capsule

A

Bowman’s space

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39
Q

what is the PCT

A

proximal convoluted tubule

  • continuation from Bowman’s capsule
  • 15mm long, single layer of cells along wall with microvilli (brush border) along the lumen
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40
Q

function of microvilli in PCT

A

provide large surface area for reabsorption

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41
Q

function of PCT

A

major site of sodium reabsorption (and other substances) as filtrate travels through tubules

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42
Q

Loop of Henle composed of?

A

composed of descending and ascending loops

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43
Q

functional characteristic of Loop of Henle depends on what?

A

function varies by location

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44
Q

2 locations of Loop of Henle

A
  1. nephrons located near medulla (juxtamedullary nephron)

2. nephrons in cortical area (superficial cortical and mid cortical nephrons)

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45
Q

function of Loop of Henle - nephrons located near medulla

A

Loop of Henle extends deep into the medulla - concetrates urine

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46
Q

function of Loop of Henle - in cortical area

A

Loop of Henle - short and only partially extend into medulla - doesn’t play role in concentrating urine

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47
Q

location of DCT and what it stands for

A

distal convoluted tubule

-begins at macula densa and end at connection to collecting duct

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48
Q

function of DCT

A
  1. early DCT - continues to dilute filtrate as reabsorbs sodium
  2. late DCT - begins to concentrate the fluid as it enters collecting duct
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49
Q

DCT’s from many nephrons drain into?

A

single collecting duct

50
Q

collecting duct descends where?

A

to the renal papilla and drain into minor calyces

51
Q

function of collecting duct

A

final concentration of urine

52
Q

how are kidneys unique?

A

they have two successive capillary networks

53
Q

pathway of blood supply to the kidney

A

descending aorta –> R/L renal arteries –> multiple branches eventually form afferent glomerular arterioles –>supply glomerular capillary beds (site of filtration)

54
Q

what happens to blood after glomerular capillary beds

A

blood exits glomerular capillary beds via efferent arterioles and contribute to two capillary beds in the nephron

55
Q

what are peritubular capillary beds

A

surround the PCT and DCT and some of the short Loop of Henle

56
Q

function of peritubular capillary beds

A

secretion and reabsorption of filtrate throughout the tubules of the nephrons

57
Q

what two capillary beds does the blood from efferent arteriole contribute to?

A
  1. pertubular capillaries

2. vasta recta

58
Q

what is the vasa recta

A

run parallel to the long loops of Henle

59
Q

function of vasta recta

A

plays critical role in concentrating urine by regulating concentration gradients along loop of Henle

60
Q

pressure in glomerular capillary beds and what does this facilitate?

A

high pressure system to encourage filtration

61
Q

pressure of glomerular capillary bed at start vs end

A

-45mmHg at the start

pressure drops by 1-3 mmHg at the end of glomerular capillary beds

62
Q

pressure in peritubular capillaries and what does this facilitate

A

lower pressure to encourage exchange (absorption/secretion)

8mmHg

63
Q

blood leaves the kidney via what vein

A

renal vein

64
Q

what is the pressure of blood as it leaves kidney via renal vein

A

4mmHg

65
Q

what is RBF

A

renal blood flow - volume of blood that flows thru the glomerular capillaries of both kidneys/min

66
Q

normal RBF

A

1.2L/min (20-25% of resting CO)

67
Q

what is RPF

A

renal plasma flow - volume of plasma that flows thru the glomerular capillaries of both kidneys/min

68
Q

avg RPF

A

600-700ml/min

69
Q

how to calculate RPF

A

RPF = RBF x (1-HCT)

if HCT = 45% then 1.2*(1.0 - 0.45) = 660 ml/min

70
Q

what is the GFR

A

glomerular filtration rate - volume of plasma that is filtered into Bowman’s capsule per unit of time

71
Q

approx how much of the plasma flowing thru glomerular capillaries of both kidneys will filter into Bowman’s capsule?

A

20-25%

72
Q

avg GFR

A

120ml/min

73
Q

calculate GFR

A

GFR = 20% x RPF

0.2* 600ml/min = 120ml/min

74
Q

what happens to the remaining 80% of RPF that does not flow thru glomerular capillaries

A

flow to peritubular capillaires/vasa recta

75
Q

how much of the GFR is reabsorbed back into the blood stream

A

approx 98-99% is reabsorbed into the peritubular capillaries as it travels thru the tubules

76
Q

what is the FF

A

filtration fraction - ratio of GFR to RPF

77
Q

avg FF?

A
  1. 2

0. 2 = 120/660

78
Q

what volume (and %) of GFR is excreted / min

A

1-2ml (1-2%)

79
Q

calculate urine production/min

A

urine output = GFR * 1.5%

ex. 120 ml/min * 0.015 = 1-2 ml/min

80
Q

how much plasma do the kidneys filter in a day

A

approx 180L/day (based on GFR of slightly >120ml/min)

81
Q

what is average urine output per day

A

1-2L/day

82
Q

how much would kidney reabsorb each day?

A

approx 178-179 L/day

83
Q

how long does it take to filter entire plasma volume

A

45 mins

84
Q

renal blood flow and pressure must be maintained at _______ levels for optimal GFR/filtration function

A

constant

85
Q

GFR is directly related to what

A

RBF

-if decr in RBF = decr in GFR

86
Q

what could give you a decreased RBF?

A

decreased MAP or increased total vascular resistance

87
Q

how does the body maintainRBF/GFR despite systemic changes in MAP/vascular resistance?

A

the body has feedback mechanisms to maintain them

88
Q

how is RBF/GFR regulated

A
  1. autoregulation
  2. neuroregulation
  3. hormonal feedback mechanisms
    - the net result of all three determines actual RBF/GFR
89
Q

what is autoregulation of GFR

A

local feedback mechanism in the kidney will keep GFR constant despite fluctuations in systemic pressures/resistance

90
Q

the systemic arteriole BP can vary from what pressures without significant change in GFR?

A

80-180mmHg

91
Q

if systemic arteriole BP exceeds upper or lower threshold pressures what happens to RBF/GFR?

A
  1. if arterial pressures are great than 180-210 then RBF and GFR increase
  2. if arterial pressures are less than 70-80mmHg then RBF and GFR decrease
92
Q

how does autoregulation maintain constant GFR - if systemic pressures increase?

A

glomerular afferent arterioles will constrict
constriction of arterioles will limit RBF
this prevents an increase in GFR as systemic pressures increase

93
Q

how does autoregulation maintain constant GFR - if systemic pressure decrease?

A

glomerular afferent arterioles will dilate
dilation of arterioles will increase RBF
this prevents a decrease in GFR as systemic pressure drop

94
Q

2 mechanisms of autoregulation of the kidneys

A
  1. myogenic mechanism (stretch feedback)

2. tubuloglomerular feedback

95
Q

what is the myogenic mechanism of autoregulation of GFR

A
  • smooth muscle of afferent arteriole wall is sensitive to stretch
  • if systemic pressures cause afferent arteriole to stretch then smooth muscle constricts
  • the afferent arteriole constriction limits RBF
96
Q

what is tubuloglomerular feedback of autoregulation of GFR

A
  • macula densa located in DCT near afferent/efferent arterioles is sensitive to flow rate and sodium levels in the renal tubules (DCT)
  • changes in sodium and flow rates will also signal constriction/dilation of afferent arterioles

ex. increased NaCl thru the macula densa represents an increased GFR
ex. an increase in NaCl in the macula signals the afferent arterioles to constrict and decrease the GFR by slowing the RBF

97
Q

what is neuroregulation of GFR

A

sympathetic nervous system provides feedback mechanism to regulate/influence GFR

98
Q

if systemic BP decreases how does neuroregulation respond?

A
  • baroreceptors in aortic arch and carotid sinus sense decrease BP and stimulate sympathetic nervous system
  • sympathetic nervous system stimulates the renal/glomerular arterioles to constrict
  • arteriole constriction limits RBF which either maintains or decreases GFR
99
Q

why would a corresponding decrease in GFR be beneficial as a result of neuroregulation?

A
  1. the goal of the sympathetic nervous system is to increase systemic BP
  2. if they can decrease GFR then less sodium/water will be filtered and excreted
  3. this will promote an increase in systemic blood volume and BP
100
Q

exercise and GFR

A

sympathetic mechanisms causes the decrease in RBF and GFR that occur during exercise

101
Q

hemorrhage and GFR

A

hemorrhaging stimulates large sympathetic response for survival

-sympathetic activity decreases RBF/GFR to promote increased blood volume/pressures

102
Q

2 hormones that regulate GFR

A
  1. RAAS - decrease GFR/increase fluid resorption/decrease fluid excretion
  2. natriuretic peptides - increase GFR/decrease fluid reabsorption/increase fluid excretion
103
Q

RAAS pathway to regulate GFR

A

Liver - produces pre-angiotensin
Kidney - release renin
blood stream - renin converts pre-angiotensin to angiotensin I
lungs - produce ACE into pulm capillaries
–ACE converts angiotensin I to angiotensin II - stimulates multiple events to promote increased BP/volume and sodium retention

104
Q

where is renin synthesized and released

A

synthesized in and released from juxtaglomerular cells of juxtaglomerular apparatus
-release renin into afferent glomerular arteriole

105
Q

RAAS - goal of RAAS ?

A

to increase BP/blood volume

106
Q

stimulus of RAAS

A

decreased BP/blood volume

  • sympathetic activity stimulate renin release
  • decrease glomerular pressure stimulates renin release
  • decrease Na/Cl flow thru macula densa stimulates renin release
107
Q

action of RAAS

A

stimulate sympathetic activity and renin release

108
Q

sympathetic action due to RAAS

A
  1. increase vasoconstriction = incr BP

2. stimulate renin release

109
Q

renin activity d/t RAAS

A

angiotensin II release

110
Q

increased angiotensin II and increased aldosterone =?

A

increased fluid/NaCl reabsorption in nephron

111
Q

actions of angiotensin II

A
  1. vasoconstriction of blood vessels
  2. stimulate thirst centers in brainstem
  3. enhances sympathetic function by promoting release of norepinephrine
  4. stimulate adrenal cortex to release aldosterone (increase NaCl reabsorption in distal nephron)
  5. sitmulate posterior pituitary gland to release ADH (increases water/fluid reabsorption in distal nephron)
  6. decreases peritubular capillary hydrostatic pressure, which promotes increased fluid reabsorption in distal nephron
  7. stimulates contractions of mesangial cell (results in decr GFR)
  8. long term = vascular hypertrophy
112
Q

inhibition of renin

A

increased GFR or NaCl flow
increased systemic/glomerular BP
negative feedback of increased angiotensin II and ADH

113
Q

stimulus of renin

A

sympathetic nervous system/activity
decreased systemic/glomerular BP (renal hypotension)
decreased NaCl flow in distal tubule (macula densa receptors)

114
Q

what are natriuretic peptides

A

group of peptides that counteract the RAAS

115
Q

name the peptides included in Natriuretic peptides

A
  1. ANP (atrial natriuretic peptide)
  2. BNP (brain natriuretic peptide)
  3. CNP (C-type natriuretic peptide)
  4. urodilatin (renal natriuretic pepetide)
116
Q

where is ANP produced and secreted

A

produced and secreted from atrial walls of heart

117
Q

where is BNP produced and secreted

A

right ventricle (and brain)

118
Q

where is CNP produced/secreted

A

from vascular endothelium in heart

119
Q

where is urodilatin secreted

A

DCT/collecting ducts

120
Q

functions of ANP/BNP

A

inhibit secretion of renin and aldosterone
promote sodium/water excretion
—increase GFR = vasodilation of glomerular afferent arterioles
inhibit sodium/water reabsorption in tubules

121
Q

function of CNP

A

promotes vasodilation of blood vessels

122
Q

function of urodilatin

A

promotes sodium/water excretion in DCT/collecting ducts