Renal L3

Question 1

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

Answer 1

plasma and interstitial compartments only

Question 2

is an isotonic solution good at rehydrating cells?

Answer 2

NO

stays in the ECF and does not move into the cells

Question 3

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

Answer 3

Water is hypoosmotic

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

Rehydrates cells

Question 4

what is another name for ADH?

Answer 4

vasopressin

Question 5

what effect does alcohol have on ADH?

Answer 5

inhibits ADH-> can result in dehydration

Question 6

what is the main role of ADH in the body?

Answer 6

water reabsorption in the kidney
water retention
water balance

Question 7

where is ADH produced and stored?

Answer 7

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

Question 8

what is the trigger for ADH release?

Answer 8

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

Question 9

what is the trigger for ADH release?

Answer 9

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

Question 10

where are osmoreceptors located?

Answer 10

hypothalamus

Question 11

how do osmoreceptors work?

Answer 11

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

Question 12

relationship between plasma osmolarity and plasma AVP/ADH lvl

Answer 12

Plasma AVP/ADH increases as osmolarity increases

Question 13

what part of the tubule does the ADH act on?

Answer 13

last part of the convoluted distal tubule and the collecting duct

Question 14

how does ADH cause water reabsorption?

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

regulate BP by Na+ retention
regulate Na+ balance

Question 17

what cells respond to the decrease in NaCl content?

Answer 17

macula densa cells in the distal convoluted tubule

Question 18

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

Answer 18

by increasing prostaglandins

Question 19

what cells release Renin?

Answer 19

Juxtaglomerular

Question 20

what stimulates Renin release?

Answer 20

-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

Question 21

renin-angiotensin system

Answer 21

Question 22

where is aldosterone released from?

Answer 22

adrenal cortex

Question 23

what is the action of aldosterone in the kidney?

Answer 23

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!!!

Question 24

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

Answer 24

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

increased Blood (plasma) Volume

Question 25

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

Answer 25

-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

Question 26

what are the effects of angiotensin 2?

Answer 26

- 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

Question 27

how do ACE inhibitors work?

Answer 27

inhibit ACE reduce angiotensin 2 lvls work by getting rid of Na+ and water reduce BP and BV helps with edema and heart expansion

Question 28

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

Answer 28

Hemorrhage- loss of Na+ AND water

Question 29

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

Answer 29

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

Question 30

what stimulates ANP secretion?

Answer 30

stretching of the atria of the heart

Question 31

what is the mechanism and site of action of ANP?

Answer 31

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)

Question 32

what are the effects of ANP?

Answer 32

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

Question 33

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

Answer 33

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

Question 34

what is the thirst mechanism for regulating water intake?

Answer 34

Question 35

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

Answer 35

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

Question 36

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

Answer 36

10 % ( ~500mL)