salt and water balance 2

Question 1

what is aldosterone released in response to?

Answer 1

high K+

angiotensin 2 acting on adrenal glands

Question 2

describe the action of aldosterone

Answer 2

aldosterone once in the kidney binds to MR, causing insertion of ENaC channels. This allows Na+ to pass through and get reabsorbed into the blood

Question 3

describe the difference between the regulation of ECF volume and osmolality

Answer 3

osmolality = regulated tightly by changes in renal water handling (ADH mediator)

ECF volume = regulated by changes in renal Na+ handling varies throughout a day (mediator = renin-angiotensin & SNS)

Question 4

what increases Na+ reabsorption

Answer 4

• RAA system

- SNS

Question 5

what decreases Na+ reabsorption and describe its action

Answer 5

ANP

• blocks ENaC channel and inhibits Na/K/ATPase
• inhibits aldosterone release
• inhibits renin release
• vasodilates afferent arterioles (increasing GFR)

Question 6

define the receptors that sense the change and result in the release of ADH

Answer 6

increased osmolality = hypothalamic osmoreceptors

decreased BP = carotid and aortic baroreceptors

decreased stretch due to low BV = atrial stretch receptors