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Physiology II > Renal Physiology: Control of Extracellular Fluid > Flashcards

Renal Physiology: Control of Extracellular Fluid Flashcards

1
Q

Sodium regulation responds primarily to changes in what?

A

blood volume

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2
Q

What is the primary effector for controlling sodium?

A

RAAS

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3
Q

Water regulation responds to changes in…

A

osmolarity and ECF volume

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4
Q

what is the primary effector for water regulation?

A

ADH

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5
Q

This hormone stimulates sodium reabsorption in the late distal tubule and collecting duct.

A

Aldosterone

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6
Q

Aldosterone regulates sodium reabsorption, but also stimulates the secretion of…

A

potassium

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7
Q

What stimulates the release of aldosterone?

A

increased [ATII] or plasma [K+]

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8
Q

Aldosterone accounts for 2-3% of filtered sodium… this amounts to how many grams of NaCl per day?

A

30g

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9
Q

What is an aldosterone antagonist?

A

spironolactone

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10
Q

To what cells in the late distal tubule does aldosterone bind?

A

principal cells

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11
Q

on the principal cells, what receptor does aldosterone bind to?

A

intracellular mineralcorticoid receptor (MR)

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12
Q

The Aldosterone-MR complex up regulates…

A

apical ENaCs and K+ channels

sodium/potassium ATPase, hydrogen-ATPase

Mitochondrial metabolism

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13
Q

Increased ATII concentration is sensed by the ______ whch stimulates release of aldosterone.

A

adrenal cortex

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14
Q

Angiotensin II stimulates what channel protein in the proximal nephron?

A

sodium hydrogen exchange (NHE)

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15
Q

This hormone’s general function is to increase salt retention and increase arterial blood pressure…

A

Angiotensin II

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16
Q

What hormone stimulates the release of aldosterone?

A

ATII

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17
Q

ATII has what effect on thirst?

A

increases thrist

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18
Q

What effect does AT II have on RBF?

A

reduces RBF

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19
Q

Which arteriole does ATII act upon?

A

efferent arteriole

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20
Q

At low levels of ATII, what happens to GFR?

A

maintained or slightly increases

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21
Q

At high levels of ATII, what happens to GFR?

A

GFR decreases

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22
Q

Why does GFR decrease with high dose of ATII?

A

effect on afferent arterioles which reduces RBF

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23
Q

Why is GFR maintained at low dose of ATII?

A

vasoconstriction of efferent arterioles ensures GFR is maintained.

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24
Q

ATII stimulates the production of two vasodilator that act on the afferent and efferent arterioles, thus protecting RBF… what are those two vasodilators?

A

PGE2 and PGI2

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25
Q

Where is renin released?

A

juxtaglomerular apparatus

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26
Q

ATII levels are primarily controlled by what hormone?

A

renin

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27
Q

What are the three broad components to renin release?

A

intrarenal baroreceptors (BP)

macula densa (Sodium Conc.)

renal sympathetic nerves (SNS stim/Epi)

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28
Q

The intrarenal baroreceptors are what type of JGA cell?

A

granular cells

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29
Q

granular cells act as ______ which respond to what change in the afferent arterioles

A

baroreceptors

stretch

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30
Q

renin release from the intrarenal baroreceptors has a ______ relationship with pressure in the afferent arterioles

A

inverse

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31
Q

The macula densa senses GFR changes via changes in flow to the distal tubule. What relationship does MD renin release have with GFR?

A

inverse

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32
Q

Renal sympathetic nerve stimulation via _______ receptors increases what?

A

beta receptors

increase renin release

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33
Q

In a hemorrhage, low BP stimulates renin production via…

A

intrarenal baroreceptors

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34
Q

in a hemorrhage, what SNS receptor is stimulated on which cells?

A

Beta receptors on granular cells

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35
Q

In a hemorrhage, the macula densa senses a decreased renal blood flow/GFR which stimulates granular production of…

A

renin

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36
Q

Which region of the nephron is responsible for sensing and initiating the integrated response that leads to renin secretion?

A

the JGA

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37
Q

A decreased renal arteriole stretch and decreased tubular sodium load stimulates the release of…

A

renin

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38
Q

Increased plasma renin causes increased presence of ___

A

ATI

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39
Q

What enzyme is responsible for converting ATI to ATII

A

ACE

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40
Q

ATII stimulates the secretion of_________, which lowers sodium excretion and therefor eincreases blood volume

A

aldosterone

41
Q

This hormone is released from the atria when blood pressure is high

A

ANP

42
Q

ANP has what effects on the renal arterioles?

A

dilates afferent

constricts efferent

43
Q

ANP will have what effect on GFR and the FL of sodium?

A

increases GFR and sodium filtered load

44
Q

What are the two ways by which ANP decreases NaCl reabsorption?

A

inhibits renin/aldosterone secretion

inhibits sodium uptake by medullary collecting ducts

45
Q

Does ADH have an effect on NaCl excretion?

A

very small

46
Q

Which hormone is the most important for regulating water balance?

A

ADH

47
Q

ADH stimulates adenylate cyclase and cAMP to increase the expression of…

A

aquaporins

48
Q

Hypothalmamic osmoreceptors are sensitive to small changes in…

A

plasma osmolarity

49
Q

Hypovolemia has what effect on ADH secretion?

A

stimulates ADH secretion

50
Q

ADH has three main affects that impact water balance… they are…

A

increase CD water and urea permeability

increase NKCC2 transporters to increase medullary gradient

51
Q

Decreased plasma volume leads to decreased BP. What mediates ADH secretion in this scenario?

A

cardiovascular baroreceptors

52
Q

Increased ADH means _______ H2O excretion

A

decreased

53
Q

Excess water leads to decreased fluid osmolarity, leading to decreased ADH secretion. This reflex is mediated by…

A

osmoreceptors

54
Q

Does drinking a large amount of water lead to increased solute excretion?

A

no… large volume of dilute urine excreted, but solute excretion remains constant

55
Q

This measure is the ml/min of blood plasma that is cleared of osmotically active particles…

A

osmolar clearance

56
Q

osmolar clearance is expressed by what equation…

A

Cosm = Uosm(V) / Posm

57
Q

Normal Cosm is…

A

1 to 2 ml/min

58
Q

Reduced Cosm leads to…

A

positive osmolar balance–gaining osmoles and water

59
Q

What can cause a reduced Cosm?

A

decreased GFR, increased aldosterone

60
Q

Increased Cosm leads to…

A

dumping of osmolytes and a loss of ECF

61
Q

What causes increased Cosm?

A

diuretics and/or low aldosterone

62
Q

Dehydration results in ___osmotic volume ______

A

hyperosmotic volume contraction

63
Q

What type of fluid shift occurs from diabetes insipidus?

A

hyperosmotic volume contraction

64
Q

This condition presents with the following characteristics:

high plasma osmolality
low urine osmolality
polyuria
polydipsia

A

Diabetes insipidus

65
Q

What is the major cause of the sxs of diabetes insipidus?

A

low or ineffective ADH

66
Q

Neurogenic cause of diabetes insipidus is due to…

A

hypothalmic-pituitary injury

insufficient ADH secretion

67
Q

Will neurogenic diabetes insipidus patients respond to exogenous ADH?

A

yes

68
Q

Nephrogenic diabetes insipidus is due to…

A

insufficient renal response to ADH

69
Q

What are some common causes of nephrogenic diabetes insipidus?

A

defective V2 receptor

lithium toxicity

hypercalcemia

70
Q

Describe the plasma concentration of ADH in nephrogenic diabetes insipidus?

A

high plasma ADH

71
Q

An acute water load causes what type of fluid shift?

A

hyposmotic volume expansion

72
Q

What is the mechanism of hyposmotic volume expansion in acute water load?

A

Excess water –> decreased plasma osmolality –> decreased ADH –> decreased CD water permeability –> increased diuresis

73
Q

SIADH leads to what type of fluid shift?

A

hyposmotic volume expansion

74
Q

What are common causes of SIADH?

A

head injury and lung tumors causing excessive ADH secretion

75
Q

SIADH results in chronic ECF ______ and ______natremia

A

dilution

hyponatremia

76
Q

What causes the excess renal sodium loss in SIADH?

A

decreased aldosterone and increased ANP

77
Q

What cation determines the volume of the ECF compartment?

A

sodium

78
Q

Sodium loss from diarrhea, vomiting is ____tonic

A

isotonic

79
Q

Changes in sodium concentration in the ECF are generally caused by changes in ________

A

body water content

80
Q

Hyponatremia is sodium concentration of…

A

< 135 mEq/L

81
Q

What causes hyponatremia due to blood volume depletion

A

excess ADH

Thirst

82
Q

What causes hyponatremia due to excessive water conservation?

A

SIADH

83
Q

What causes hyponatremia secondary to excessive water intake

A

water intoxication

84
Q

Hypernatremia is rarely chronic because…

A

excess sodium causes thirst

85
Q

Hypernatremia is defined as sodium concentration of…

A

> 145 mEq/L

86
Q

What are two common causes of hypernatremia?

A

loss of water from dehydration or diabetes insipidus

gain of sodium

87
Q

Muscle stretch in the kidneys causes _______ which stimulates _________ to force urine into bladder…

A

causes pacemaker activity

stimulates peristalsis

88
Q

What causes the urge to urinate?

A

stretching of trigone

89
Q

When is the urge to void felt?

A

150 ml

90
Q

What is the max volume of the bladder?

A

500-800 ml

91
Q

SNS predominates the bladder during…

A

filling

92
Q

PNS predominates in the bladder during…

A

micturition

93
Q

SNS causes the detrusor to _____ during filling and the internal sphincter to ______

A

detrusor relaxation

sphincter contraction

94
Q

The PNS causes the detrusor to _________ and the internal sphincter to ________

A

detrusor contract

sphincter relaxation

95
Q

Is the external sphincter under ANS or voluntary control?

A

voluntary

96
Q

What SNS receptor type is responsible for detrusor relaxation?

A

Beta 2

97
Q

What SNS receptor type is responsible for the internal sphincter contraction?

A

alpha 1

98
Q

What PNS receptor types are responsible for micturition?

A

muscarinic

Physiology II (28 decks)

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