Chapter 28

Question 1

where is adh synthesized

Answer 1

in the hypothalamus

Question 2

adh is transported to the ____ and stored there

Answer 2

posterior pituitary

Question 3

what is the stimulus for adh

Answer 3

osmotic change in body fluids
hemodynamic change (decrease or pressure)
angiotensin II

Question 4

what are the effects of adh

Answer 4

increased water reabsorption by kidney (direct and via the increase in Na)
concentrated urine
vasconstriction

Question 5

what is the action of adh on the kidney

Answer 5

increase in permeability to water in the late dt and cd (primary action)
increase in permeability to urea in medullary CD

Question 6

What does reabsorption mean

Answer 6

leaving the tubule and entering the ISF

Question 7

What is the vascular receptor for adh

Answer 7

V1

Question 8

what is the renal receptor for adh

Answer 8

v2

Question 9

binding of adh to v2 results in

Answer 9

increased insertion and synthesis of aquaporins into the apcial membrane of the late dt and cd

Question 10

with the removal of adh, what happens to these aquaporins

Answer 10

they are reinternalized into the cell thus rendering apical membrane impermeable to water

Question 11

what also cause thirst

Answer 11

changes in plasma osmolality and blood volume or pressure

Question 12

what is the level of the thirst threshold compared to adh secretion threshold

Answer 12

thirst threshold is higher than the threshold for adh secretion

Question 13

thirst is satisfied by what

Answer 13

the act of drinking even before sufficient water is absorbed from the GIT to correct plasma osmolality

Question 14

relief of thirst

Answer 14

short lived; not satisfied until the deficit is corrected

Question 15

where is the thirst center

Answer 15

inthe hypothalamus, in same region that regulates ADH

Question 16

Control of extrallular fluid sodium concentration in the absence of adh and thirst mechanisms

Answer 16

it is poor

Question 17

sodium concentration without aldosterone feedback control

Answer 17

sodium concentration is maintained relatively constant over this wide range of sodium intake, with or without aldosterone feedback control because aldosterone affects Na and H2O

Question 18

Why dont angiotensin II and aldosterone have a major effect on plasma sodium concentration

Answer 18

angiotensin II and aldosterone increase both sodium and water reabsorption by the renal tubules, leading to increases in extracellular fluid volume and sodium quantity but little change in sodium concentration

Question 19

what are the 2 forms of polydypsia(?) in diabetes insipidus

Answer 19

Central or nephrogenic

Question 20

what is cenral

Answer 20

inadequate manufacture or release of ADH

Question 21

what is nephrogenic

Answer 21

insensitivity of kidney to adh

Question 22

what are the clinical signs

Answer 22

hyposthenuria (very dilute urine)

polyuria/polydipsia (increased urination and water drinking)

Question 23

water deprivation of these animals can lead to

Answer 23

hyperosmotic body fluids

Question 24

what is the osmolarity of the ISF throughout the renal cortex

Answer 24

isotonic

Question 25

the osmolarity of the ISF in teh renal medulla does what from its boundary witht the cortex to its junction with the renal pelvis

Answer 25

increases progressively

Question 26

what is this gradient established by

Answer 26

the countercurrent multiplication in the loop of Henle

Question 27

it is preserved by the ______

Answer 27

countercurrent exchanage in the vasa recta