Hormones acting on kidney

Question 1

ANP

Answer 1

At the proximal tubule,
Secreted in response to increased atrial pressure
Causes increase in GFR and Na+ filtration
But no compensatory Na+ reabsoprtion in distal nephrone

Net result: NA+ loss and volume loss

Question 2

PTH

Answer 2

Secreted in response to low plasma Ca, high plasma Pi, or decrease in 1,25-(OH)2-vitamin D

Causes increase Ca2+ reabsorption at DCT,
Decreases Pi reabsorption at PCT,
Increases 1,25-(OH)2 vit D production

Additional effect: Increase Ca+ and Pi absorption from gut

Question 3

Renin

Answer 3

Secreted from JGA in response to low blood volume,
converts angiotensinogen (from liver) to AT 1, which then
gets converted to AT II by ACE (in lung)

Question 4

ATII

Answer 4

Synthesized in response to low BP
Causes efferent arteriole constriction
Increases GFR and FF,
BUT WITH compensatory Na+ reabsorption in proximal and distal nephron.

Net: preservation of renal function in low volume state (increase FF) with simultaneous Na+ reabsorption (both proximal and distal) to decrease additional volume loss

Question 5

Aldo

Answer 5

Secreted in response to low blood volume via AT II
to high plasma [K+]

Causes increase in Na+ reabsorption, K+ secretion, H+ secretion.

Question 6

ADH (vasopressin)

Answer 6

Secreted in response to increased plasma osmolarity and low blood volume

Binds to receptors on principal cells, causing an increase number of water channels and increase H2O reabsorption.