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Medsci 142 > Renal L3 > Flashcards

Renal L3 Flashcards

1
Q

when considering the body fluid compartments( plasms, interstitial, intracellular) an intravenous infusion of an isotonic solution will result in an in increase in the volume of:

-all compartments
-plasma only
-interstitial compartment only
-plasma and interstitial compartments only
-intracellular compartment only

A

plasma and interstitial compartments only

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2
Q

is an isotonic solution good at rehydrating cells?

A

NO

stays in the ECF and does not move into the cells

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3
Q

What is the effect of water ingestion on the ICF, and ECF( plasma and interstitial fluid)?

A

Water is hypoosmotic

water rapidly equilibrates throughout ECF & ICF. Osmolarity decreases everywhere. Water is evenly distributed.

Rehydrates cells

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4
Q

what is another name for ADH?

A

vasopressin

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5
Q

what effect does alcohol have on ADH?

A

inhibits ADH-> can result in dehydration

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6
Q

what is the main role of ADH in the body?

A

water reabsorption in the kidney
water retention
water balance

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7
Q

where is ADH produced and stored?

A

the precursor to ADH (AVP) is made in the hypothalamus and stored in vesicles in the posterior pituitary

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8
Q

what is the trigger for ADH release?

A

osmoreceptors innervating the hypothalamus sense:

-increase in Na+ concentration
-Increase in osmolarity

e.g. from dehydration

-> signal send to the pituitary to release ADH into the bloodstream

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9
Q

what is the trigger for ADH release?

A

osmoreceptors innervating the hypothalamus sense:

-increase in Na+ concentration
-Increase in osmolarity
* also Blood Volume

e.g. from dehydration

-> signal send to the pituitary to release ADH into the bloodstream

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10
Q

where are osmoreceptors located?

A

hypothalamus

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11
Q

how do osmoreceptors work?

A

osmoreceptors have stretch-inhibited(shrink-activated) cation channels

when the cell shrinks due to the hypertonic stimulus cation( Na+) channels open

Na+ entering the cell triggers AP

increased osmolarity- increased firing rate of osmoreceptors

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12
Q

relationship between plasma osmolarity and plasma AVP/ADH lvl

A

Plasma AVP/ADH increases as osmolarity increases

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13
Q

what part of the tubule does the ADH act on?

A

last part of the convoluted distal tubule and the collecting duct

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14
Q

how does ADH cause water reabsorption?

A

ADH binds to the receptors on the basolateral side of the principal cells in the collecting duct.

This triggers a 2nd messenger pathway, causing vesicles inside the cell to merge and insert aquaporin-2 channels into the apical membrane.

Water can now move out of the filtrate through aquaporin-2 channels into the cells

the basolateral membrane is always relatively permeable to water, thus water can now move via osmosis back into the blood

This results in a small volume of concentrated urine being produced

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15
Q

what is the alternative way for ADH to be stimulated apart from Na+ concentration and osmolarity?

A

decrease in Blood pressure( 10-15%)
decreased in plasma volume
this is sensed by baroreceptors
stimulate ADH release

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16
Q

what is the main function of the renin-angiotensin-aldosterone system?

A

regulate BP by Na+ retention
regulate Na+ balance

17
Q

what cells respond to the decrease in NaCl content?

A

macula densa cells in the distal convoluted tubule

18
Q

how do macula densa cells respond to decrease in NaCl content?

A

by increasing prostaglandins

19
Q

what cells release Renin?

A

Juxtaglomerular

20
Q

what stimulates Renin release?

A

-low NaCl concentration in the distal tubule( sensed by Macula Densa cells)

-decreased perfusion pressure in the afferent arteriole( sensed by granular cells)

-increased sympathetic activity( via baroreflex)

i.e Low BP, BV, or NaCl content

21
Q

renin-angiotensin system

A
22
Q

where is aldosterone released from?

A

adrenal cortex

23
Q

what is the action of aldosterone in the kidney?

A

Aldosterone acts on the principal cells of the distal tubule and collecting ducts to increase transcription of Na+/K+ ATPase pumps in the basolateral membrane thus increasing Na+ reabsorption and K+ excretion
Water reabsorption may also increase as long as ADH is also present!
-Na+ and water retention!!!

24
Q

what is the effect of eating salty chips on plasma, ICF, and interstitial volume?

A

increased osmosis of water from intracellular fluid to interstitial fluid to plasma

increased Blood (plasma) Volume

25
Q

what is the effect of eating salty chips on the body?

A

-increase in BV
-decrease in renin release
-increased atrial natriuretic peptide(ANP)
-reduced reabsorption of NaCl by the kidneys
-increased loss of water in urine by osmosis

all eventually lead to a decrease in BV

26
Q

what are the effects of angiotensin 2?

A
  • it is a potent vasoconstrictor, thus it decreases glomerular filtration by vasoconstricting the afferent arteriole

-it increases Na+ and water reabsorption in the proximal and distal convoluted tubules

-it stimulates the release of aldosterone from the adrenal cortex. Aldosterone acts on the collecting ducts to reabsorb more Na+ and Cl-

-stimulates thirst and salt intake, release of ADH

27
Q

how do ACE inhibitors work?

A

inhibit ACE
reduce angiotensin 2 lvls
work by getting rid of Na+ and water
reduce BP and BV

helps with edema and heart expansion

28
Q

in what situation would both ADH and renin-angiotensin systems be working together?

A

Hemorrhage- loss of Na+ AND water

29
Q

why would ADH not be used to respond to eating salty chips?

A

eating salty cheaps while increasing Na+ concentration and osmolarity also increases Blood Volume, which opposes the increase in osmolarity.

30
Q

what stimulates ANP secretion?

A

stretching of the atria of the heart

31
Q

what is the mechanism and site of action of ANP?

A

suppresses reabsorption of Na+ and water in proximal tubules and collecting duct. Inhibits secretion of aldosterone and ADH.

(prevents further increase in BV and BP)

32
Q

what are the effects of ANP?

A

increases excretion of Na+ in urine(natriuresis) , increases urine output (diuresis) and thus decreases BV and BP

33
Q

what are the responses of the body to blood loss(hypovolemic/isotonic)?

A

Sensed by juxtaglomerular cells and
arterial baroreceptors
↑sympathetic activity
↑ADH and ↑renin/angiotensin
II/aldosterone
Vasoconstriction
Conservation of water and Na+

34
Q

what is the thirst mechanism for regulating water intake?

A
35
Q

what is the order of events that happen in the body in the case of hemorrhage?

A
  1. Baroreceptors try to maintain BP
  2. Try to maintain Osmolarity: fluid shifts
  3. try to restore Blood Volume: hormones. Takes hours
  4. takes 7-14 days to replace blood cells
36
Q

how much blood volume can be lost with BP remaining the same?

A

10 % ( ~500mL)

Medsci 142 (32 decks)

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