Urinary System Flashcards

1
Q

what is the primary function of the urinary system

A

production of urine

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2
Q

how is urine produced by the urinary system

A

thru regulating the extracellular fluid environment in the body

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3
Q

what is the extracellular fluid in the body

A

interstitial fluid and plasma

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4
Q

specifically, how can the extracellular fluid environment in the body be regulated (i.e. what components/characteristics of the plasma can be controlled)

A
  • ionic composition
  • volume and blood pressure
  • osmolarity
  • pH
  • metabolic waste products
  • foreign substances
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5
Q

how is plasma volume regulated

A

by controlling rate of water excretion in the urine

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6
Q

plasma volume and pressure have direct effects on

A

total blood volume and total blood pressure

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7
Q

regulation of plasma osmolarity refers to

A

regulation of solute concentration thru rate of water excretion

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8
Q

regulation of plasma pH refers to

A

controlling bicarbonate and hydrogen ions in conjunction with lungs

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9
Q

what does metabolic waste refer to

A

uric acid, food additives, drugs, toxins

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10
Q

what are the secondary functions of the urinary system

A
  • secretion of erythropoietin and renin
  • activation of vitamin D3
  • gluconeogenesis
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11
Q

secretion of erythropoietin and renin can be considered what type of system function

A

hormonal

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12
Q

what is erythropoietin important for

A

stimulation of red blood cells in marrow

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13
Q

what is renin needed for

A

angiotensin production

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14
Q

what is angiotensin

A

hormone that regulates salt and water balance, which regulates blood pressure

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15
Q

what is vitamin D3 important for

A

regulating blood calcium and phosphate levels

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16
Q

what is gluconeogenesis

A

production of glucose from glycerol and amino acids

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17
Q

draw out a diagram on a kidney including the arteries stemming from the renal artery: interlobular, arcuate, interlobar, segmental

A

….

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18
Q

what is the hilus

A
  • indentation area of kidney
  • variety of different vessels will enter/exit in this area
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19
Q

why are renal arteries important

A

they receive 20% of cardiac output at rest and directs this into the kidney itself

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20
Q

draw out a flow chart of renal artery branching

A

renal → segmental → interlobar → arcuate → interlobular → afferent arterioles → glomerular capillary bed

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21
Q

what stems (leaves) from the glomerular capillary bed; draw a flowchart

A

glomerular capillary bed → efferent arteriole → peritubular capillaries and vasa recta

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22
Q

where are peritubular capillaries found

A

cortex (outer layer of kidney)

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23
Q

where is the vasa recta found

A

medulla (inner part of kidney)

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24
Q

what is the relationship between vasa recta and peritubular capillaries

A

vasa recta are peritubular capillaries around the loop of Henle in the juxtamedullary nephrons only

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25
Q

how do kidneys regulate the composition of plasma

A

thru exchanging water and solutes between plasma and fluid in renal tubules

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26
Q

where do the substances removed from plasma go

A

urine excretion

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27
Q

what are the exchange processes occurring within the nepron

A
  • glomerular filtration
  • reabsorption
  • secretion
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28
Q

what is glomerular filtration

A

bulk flow of protein-free plasma from glomerulus to Bowman’s capsule

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29
Q

describe the pathway of blood flow during basic renal exchange processes (incl. excretion) in a summary diagram; use arrows to indicate exchange movement direction

A

….

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30
Q

what is reabsorption

A
  • selective transport of molecules from renal tubules to interstitial fluid
  • molecules are first selectively transported to interstitial fluid outside of peritubular capillaries
  • reabsorbed molecules enter peritubular capillaries thru diffusion
  • molecules returned to general circulation
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31
Q

describe secretion

A

selective transport of molecules from plasma of peritubular capillaries back to renal tubules

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32
Q

define excretion

A

elimination of materials from body in the form of urine

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33
Q

what barriers must glomerular filtrate cross to enter the Bowman’s capsule

A
  • capillary endothelial layer
  • surrounding epithelial layer
  • basement membrane (sandwiched between the 2 layers mentioned above)
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34
Q

what cells is the surrounding epithelial layer (in reference to glomerular filtration) made of

A

podocytes

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35
Q

the wall of the Bowman’s capsule and renal tubule are considered _______ layers of endothelial cells

A

continuous

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36
Q

what is the role of the basement membrane; how?

A
  • to act as a primary filtration barrier
  • as fluid passes out of glomerular capillaries, it moves thru gaps in podocytes
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37
Q

what are foot processes

A
  • adhesive finger-like projections
  • interlink like a puzzle but have gaps (filtration slits)
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38
Q

what is another name for filtration slits

A

slit pores

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39
Q

what is the pathway for filtrate flow in glomerular filtration

A

fluid passes out of glomerular capillaries → in gaps of podocytes (i.e. filtration slits)

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40
Q

how is movement in glomerular filtration regulated

A

slit diaphragm (intracellular contact points)

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41
Q

what force(s) drive glomerular filtration

A
  • glomerular capillary hydrostatic pressure (P gc)
  • bowman’s capsule hydrostatic pressure (P bc)
  • glomerular osmotic pressure (π gc)
  • bowman’s capsule osmotic pressure (π bc)
42
Q

the sum of the starling forces in renal corpuscle make

A

glomerular filtration pressure

43
Q

what can we compare glomerular filtration pressure in the urinary system to

A

net filtration pressure in the circulatory system

44
Q

describe P gc

A
  • blood pressure in glomerular capillaries
45
Q

the variable P refers to

A

hydrostatic pressures

46
Q

π refers to

A

osmotic pressures

47
Q

why is the hydrostatic pressure in glomerular capillaries higher than hydrostatic pressure in most capillaries

A
  • due to the high resistance in efferent arteriole
  • consider water flowing thru a hose and a clamp was put on it
  • water would then flow backwards which increases pressure upstream the clamp
  • therefore when there is high resistance in efferent arteriole, the pressure is lower there but increases pressure on other side (in glomerular capillaries)
48
Q

what is the hydrostatic pressure of the glomerular capillaries equal to

A

60 mmHg

49
Q

what is the hydrostatic pressure of the glomerular capillaries equal to

A

15 mmHg

50
Q

why is the hydrostatic pressure of the bowman’s capsule higher than the hydrostatic pressure in interstitial fluid surrounding most capillary beds

A
  • due to large volume of fluid filtering in to bowman’s capsule
  • similar to when pouring liquid down a funnel and doing it too fast in which the fluid backs up causing back pressure
51
Q

why does π gc happen

A

presence of proteins that tend to draw fluid back into glomerulus

52
Q

what does osmotic pressure of glomerular capillaries equal to

A

29 mm Hg (which is higher than osmotic pressure in most capillaries - 25 mmHg)

53
Q

what does osmotic pressure of bowman’s capsule equal to

A

~0 mmHg (negligible)

54
Q

since proteins cannot move between plasma and bowman’s capsule, what type of force generates

A

osmotic force (proteins stay in plasma)

55
Q

proteins in the interstitial fluid around the glomerulus pull the fluid out of the capillaries into the capsule, but very little protein leaves. what does this mean for the concentration of proteins inside the bowman’s capsule

A

remains very small (leading to that ~0 mmHg amt.)

56
Q

what are the types of starling forces that affect glomerular filtration

A
  • favouring
  • opposing
57
Q

glomerular filtration pressure is the difference between

A
  • favouring and opposing filtration pressures
  • (Pgc + π bc) - (P bc + π gc)
58
Q

what are the favouring filtration pressure

A

P gc and π bc

59
Q

what are the opposing filtration pressures

A

P bc and π gc

60
Q

where the blood is actually coming from is referred to as

A

upstream (afferent)

61
Q

where the blood is actually going to is referred to as

A

downstream (efferent)

62
Q

P gc and π bc favour filtration because

A

they promote water and solutes in blood plasma to move thru glomerular filter

63
Q

P bc and π gc oppose filtration because

A

creates back-pressure

64
Q

osmotic pressure refers to

A

pressure due to solutes in the blood that can’t leave, which makes a pull to draw water back into the capillaries

65
Q

hydrostatic pressure refers to

A

pressure of a fluid on (the walls of) a confined space

66
Q

what is the renal plasma flow rate

A

625mL/min

67
Q

what is the glomerular filtration rate

A

125mL/min (180L/day)

68
Q

what is glomerular filtration rate used to estimate

A

kidney function

69
Q

define renal plasma flow

A

amount of plasma that flows thru kidneys each minute

70
Q

define glomerular filtration rate

A

volume of plasma filtered per unit time

71
Q

what is the filtration fraction

A

fraction of renal plasma volume filtered into bowman’s capsule (GFR/renal plasma flow)

72
Q

what is filtered load

A

quantity of certain solute that is filtered per unit time (GFR * plasma conc. of X)

73
Q

what classifies as a freely filterable solute

A

solute molecules that are small enough to move across glomerular membrane without restriction

74
Q

small increases in GFR lead to large increases in

A

volume of fluid filtered and excreted

75
Q

is GFR regulated or unregulated

A

regulated

76
Q

draw out the intrinsic control pathway of GFR for myogenic regulation in afferent arterioles and glomerulus

A

↑ in mean arterial pressure leads to higher pressure in afferent arteriole and higher glomerular pressure in glomerulus

afferent arteriole: ↑ press. → stretch of arteriolar smooth muscle by stretch receptors → inc. constriction → inc resistance causing lower glomerular capillary pressure

glomerulus: higher pres. from MAP balances out lower pres. from high resistance; higher gc pres → higher glomerular filtration pres. → inc in GFR

77
Q

draw out the intrinsic control pathway of GFR for tubuloglomerular feedback in afferent arterioles and glomerulus

A

↑ in mean arterial pressure leads to higher pressure in afferent arteriole and higher glomerular pressure in glomerulus

afferent arteriole ↑ press. → ↑ gc pres. in glomerulus → ↑ glomerular filtration press. → ↑ GFR → ↑ flow in macula densa → ↑ paracrine secretion → ↑ constriction in afferent arteriole → ↑ resistance → dec. in gc pressure in glomerulus (neg feedback by balance)

78
Q

what is the role of the macula densa in tubuloglomerular feedback

A

releases paracrine factors in distal tubules which the smooth muscle of afferent arteriole is sensitive to

79
Q

how do paracrine factors affect afferent arteriole

A

by constriction and relaxation

80
Q

what are examples of extrinsic control mechanisms of the GFR

A
  • hemorrhage
  • excessive sweating
81
Q

what systems and receptors are involved in extrinsic control of GFR

A
  • sympathetic nervous system
  • baroreceptors
82
Q

why does GFR rise or fall when MAP varies outside range of 80-180 mmHg

A

intrinsic mechanisms aren’t able to prevent glomerular capillary pressure changes

83
Q

draw out the extrinsic control of GFR including where negative feedbacks occur

A

84
Q

what are the end results of extrinsic control of GFR

A
  • decreased urine output
  • lower reductions in blood volume which counteracts further decreases in arterial pressure
85
Q

why does increased urine output occur at the end of extrinsic GFR control

A

to conserve water

86
Q

describe solute and water reabsorption

A

movement of filtered solutes and water from lumen of tubules back into plasma

87
Q

what percentage of most substances filtered by glomerulus are reabsorbed by renal tubules

A

100%

88
Q

where does solute and water reabsorption occur mostly

A

proximal and distal convoluted tubules

89
Q

when a substance is absorbed it must move across what number of barrier(s)

A

2

90
Q

what are the barrier(s) that reabsorbed substances must cross

A
  • epithelial cells of renal tubules
  • endothelial cells of capillaries
91
Q

what is the role of the tight junctions in the tubule epithelial cells

A

serve as connectors for cells lining tubules which makes for movement between the cells high restricted

92
Q

on the apical membrane of the tubule epithelial cells there us microvilli facing the

A

lumen of renal tubule

93
Q

the basolaterial membrane of tubule epithelial cells faces the

A

interstitial fluid in the peritubular space

94
Q

when does sodium reabsorption happen

A
  • movement happens into cell thru sodium channels or cotransport
  • movement happens into peritubular fluid thru active transport (Na+/K+ pump) across basolateral membrane
  • via diffusion thru plasma
95
Q

water reabsorption is based on

A

differences in osmolarity

96
Q

what is the “simple rule” on excretion vs reabsorption of material entering renal tubules

A

assumed that material which enters lumen of renal tubules is excreted unless it is reabsorbed

97
Q

the amount of substance excreted equals

A

amt filtered - amt secreted - amt reabsorbed

98
Q

excretion rate depends on what factor(s)

A
  • filtered load
  • secretion rate
  • reabsorption rate
99
Q

if the amount of solute excreted per minute is less than filtered load, we can say the solute was

A

reabsorbed

100
Q

if the amount of solute excreted per minute was greater than filtered load, we can say that the solute was

A

secreted