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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
Where is renin released?
juxtaglomerular apparatus
26
ATII levels are primarily controlled by what hormone?
renin
27
What are the three broad components to renin release?
intrarenal baroreceptors (BP) macula densa (Sodium Conc.) renal sympathetic nerves (SNS stim/Epi)
28
The intrarenal baroreceptors are what type of JGA cell?
granular cells
29
granular cells act as ______ which respond to what change in the afferent arterioles
baroreceptors stretch
30
renin release from the intrarenal baroreceptors has a ______ relationship with pressure in the afferent arterioles
inverse
31
The macula densa senses GFR changes via changes in flow to the distal tubule. What relationship does MD renin release have with GFR?
inverse
32
Renal sympathetic nerve stimulation via _______ receptors increases what?
beta receptors increase renin release
33
In a hemorrhage, low BP stimulates renin production via...
intrarenal baroreceptors
34
in a hemorrhage, what SNS receptor is stimulated on which cells?
Beta receptors on granular cells
35
In a hemorrhage, the macula densa senses a decreased renal blood flow/GFR which stimulates granular production of...
renin
36
Which region of the nephron is responsible for sensing and initiating the integrated response that leads to renin secretion?
the JGA
37
A decreased renal arteriole stretch and decreased tubular sodium load stimulates the release of...
renin
38
Increased plasma renin causes increased presence of ___
ATI
39
What enzyme is responsible for converting ATI to ATII
ACE
40
ATII stimulates the secretion of_________, which lowers sodium excretion and therefor eincreases blood volume
aldosterone
41
This hormone is released from the atria when blood pressure is high
ANP
42
ANP has what effects on the renal arterioles?
dilates afferent constricts efferent
43
ANP will have what effect on GFR and the FL of sodium?
increases GFR and sodium filtered load
44
What are the two ways by which ANP decreases NaCl reabsorption?
inhibits renin/aldosterone secretion inhibits sodium uptake by medullary collecting ducts
45
Does ADH have an effect on NaCl excretion?
very small
46
Which hormone is the most important for regulating water balance?
ADH
47
ADH stimulates adenylate cyclase and cAMP to increase the expression of...
aquaporins
48
Hypothalmamic osmoreceptors are sensitive to small changes in...
plasma osmolarity
49
Hypovolemia has what effect on ADH secretion?
stimulates ADH secretion
50
ADH has three main affects that impact water balance... they are...
increase CD water and urea permeability increase NKCC2 transporters to increase medullary gradient
51
Decreased plasma volume leads to decreased BP. What mediates ADH secretion in this scenario?
cardiovascular baroreceptors
52
Increased ADH means _______ H2O excretion
decreased
53
Excess water leads to decreased fluid osmolarity, leading to decreased ADH secretion. This reflex is mediated by...
osmoreceptors
54
Does drinking a large amount of water lead to increased solute excretion?
no... large volume of dilute urine excreted, but solute excretion remains constant
55
This measure is the ml/min of blood plasma that is cleared of osmotically active particles...
osmolar clearance
56
osmolar clearance is expressed by what equation...
Cosm = Uosm(V) / Posm
57
Normal Cosm is...
1 to 2 ml/min
58
Reduced Cosm leads to...
positive osmolar balance--gaining osmoles and water
59
What can cause a reduced Cosm?
decreased GFR, increased aldosterone
60
Increased Cosm leads to...
dumping of osmolytes and a loss of ECF
61
What causes increased Cosm?
diuretics and/or low aldosterone
62
Dehydration results in ___osmotic volume ______
hyperosmotic volume contraction
63
What type of fluid shift occurs from diabetes insipidus?
hyperosmotic volume contraction
64
This condition presents with the following characteristics: high plasma osmolality low urine osmolality polyuria polydipsia
Diabetes insipidus
65
What is the major cause of the sxs of diabetes insipidus?
low or ineffective ADH
66
Neurogenic cause of diabetes insipidus is due to...
hypothalmic-pituitary injury insufficient ADH secretion
67
Will neurogenic diabetes insipidus patients respond to exogenous ADH?
yes
68
Nephrogenic diabetes insipidus is due to...
insufficient renal response to ADH
69
What are some common causes of nephrogenic diabetes insipidus?
defective V2 receptor lithium toxicity hypercalcemia
70
Describe the plasma concentration of ADH in nephrogenic diabetes insipidus?
high plasma ADH
71
An acute water load causes what type of fluid shift?
hyposmotic volume expansion
72
What is the mechanism of hyposmotic volume expansion in acute water load?
Excess water --> decreased plasma osmolality --> decreased ADH --> decreased CD water permeability --> increased diuresis
73
SIADH leads to what type of fluid shift?
hyposmotic volume expansion
74
What are common causes of SIADH?
head injury and lung tumors causing excessive ADH secretion
75
SIADH results in chronic ECF ______ and ______natremia
dilution hyponatremia
76
What causes the excess renal sodium loss in SIADH?
decreased aldosterone and increased ANP
77
What cation determines the volume of the ECF compartment?
sodium
78
Sodium loss from diarrhea, vomiting is ____tonic
isotonic
79
Changes in sodium concentration in the ECF are generally caused by changes in ________
body water content
80
Hyponatremia is sodium concentration of...
< 135 mEq/L
81
What causes hyponatremia due to blood volume depletion
excess ADH Thirst
82
What causes hyponatremia due to excessive water conservation?
SIADH
83
What causes hyponatremia secondary to excessive water intake
water intoxication
84
Hypernatremia is rarely chronic because...
excess sodium causes thirst
85
Hypernatremia is defined as sodium concentration of...
>145 mEq/L
86
What are two common causes of hypernatremia?
loss of water from dehydration or diabetes insipidus gain of sodium
87
Muscle stretch in the kidneys causes _______ which stimulates _________ to force urine into bladder...
causes pacemaker activity stimulates peristalsis
88
What causes the urge to urinate?
stretching of trigone
89
When is the urge to void felt?
150 ml
90
What is the max volume of the bladder?
500-800 ml
91
SNS predominates the bladder during...
filling
92
PNS predominates in the bladder during...
micturition
93
SNS causes the detrusor to _____ during filling and the internal sphincter to ______
detrusor relaxation sphincter contraction
94
The PNS causes the detrusor to _________ and the internal sphincter to ________
detrusor contract sphincter relaxation
95
Is the external sphincter under ANS or voluntary control?
voluntary
96
What SNS receptor type is responsible for detrusor relaxation?
Beta 2
97
What SNS receptor type is responsible for the internal sphincter contraction?
alpha 1
98
What PNS receptor types are responsible for micturition?
muscarinic

Physiology II (28 decks)

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