ADH

Question 1

where is ADH produced and released from

Answer 1

produced in hypothalamus, released from posterior pituitary

Question 2

when is ADH released

Answer 2

when dehydrated, ie an increase in plasma osmolarity

Question 3

describe the effect ADH has on the water permeability of the collecting duct

Answer 3

it increases the permeability by inserting new water channels(aquaporins)

Question 4

describe the effect of high ADH conc. on water permeability of the collecting duct and therefore osmolarity of urine

Answer 4

increased permeability, allow water to leave duct, making urine hypertonic
(less urine volume)

Question 5

describe the effect of low ADH conc. on water permeability of the collecting duct and therefore osmolarity of urine

Answer 5

decreased permeability, water stays in duct, so urine hypotonic
(more urine volume)

Question 6

what is another name for ADH

Answer 6

vasopressin

Question 7

describe the tonicity of the interstitial fluid surrounding the collecting duct as it descends into the renal medulla

Answer 7

becomes more and more hypertonic as it descends

Question 8

what is the only part of the nephron ADH acts on

Answer 8

cells of distal tubule and collecting duct

Question 9

what effect does ADH have on blood vessels

Answer 9

arteriolar vasoconstriction

Question 10

what is the role of ADH in central and nephrogenic diabetes insipidus

Answer 10

central = failure to produce ADH
nephrogenic = failure to recognise/respond to ADH

Question 11

what symptoms are seen with diabetes insipidus

Answer 11

large volumes of dilute urine, due to low water reabsorption

and constant thirst

Question 12

describe how arterial pressure can influence ADH

Answer 12

if significantly reduced arterial pressure, acts to increase ADH production
(need large changes in plasma volume)