B5.040 - Renal Physiology 3

Question 1

what does furosemide target

Answer 1

NaK2Cl transporter in loop of henle

Question 2

two major factors affecting ECF volume

Answer 2

Na intake
Na excretion
total body Na content

Question 3

two factors affecting ECF osmolarity

Answer 3

water intake/excretion

Na concentration

Question 4

water balance mostly regulated by

Answer 4

kidney

Question 5

how much water is ingested/from metabolism

Answer 5

2000 mL - ingested

400 mL - metabolism

Question 6

how much water is lost through the kidney

Answer 6

1.5 L

Question 7

regulation of plasma osmotic concentration

Answer 7

osmoreceptors send signals to supraoptic and paraventricular nucleus to stimulate ADH release to posterior hypothesis to be released and affect the collecting duct to reabsorb water

Question 8

what happens after the ADH takes effect and ECF osmolarity decreases

Answer 8

it sends a negative feedback signal to the osmoreceptors which shut that system down and stop release of ADH

Question 9

synthesis of AVP

Answer 9

ADH comes from prepropressophysin which gets cleaved in neuronal axons

Question 10

describe the relationship of osmolarity to ADH

Answer 10

its linear, increase in osmolarity increases ADH

Question 11

describe relationship between blood pressure and ADH

Answer 11

a decrease in blood pressure

Question 12

how does ADH affect water reabsorption

Answer 12

ADH binds to V2 on the basolateral membrane which activates Gs to convert ATP to cAMP, which activates PKA which phosphorylates AQ2 which then translocates to the apical membrane to allow water through the cell. AQ3 and 4 are always expressed and once water is inside the cell it exits via those channels to get back into the blood stream

Question 13

once ADH ?>5mg what happens

Answer 13

it acts on smooth muscle cells in the vasculature to activate vasoconstriction

Question 14

describe the countercurrent system in the alh and dlh

Answer 14

in the dlh the water is freely permeable and it progressively leaves to go to the medulla due to the medullas high osmolarity, then as it converts to the alh the alh is impermeable to water. This means the salt will leave to enter the medulla and result in a hypotonic content of the tubule

Question 15

describe the collecting duct permeability

Answer 15

its completely impermeable to water UNLESS ADH is there and then AQ2 is able to transport water in bc of the gradient created by the alh

Question 16

factors affecting kidneys ability to concentrate urine

Answer 16

1. length of loops of henle
2. ADH levels (think DI)
3. blood flow thru medullary capillaries
4. urea concentration
5. drugs and diuretics

Question 17

what is ANP

Answer 17

peptide in atria that senses increased heart volume and stimulates Na+ loss and volume depletion

Question 18

what is BNP

Answer 18

peptide in ventricle that senses increased heart volume and stimulates Na+ loss and volume depletion

Question 19

what is CNP

Answer 19

peptide in brain senses increased intravascular volume and reacts by stimulating Na+ release and volume depletion

Question 20

what is Urodilatin

Answer 20

senses volume increase in kidney and stimulates Na+ loss