Regulation of Sodium Excretion

Question 0

What are the ECF volume sensors?

Answer 0

Atria
Thoracic veins
Pulmonary vessels

Question 1

Sodium excretion determined by

Answer 1

ECF volume

Question 2

What are the ECF pressure sensors?

Answer 2

Carotid sinus
Aortic arch
Afferent arteriole (JGA) - can release renin

Question 3

What is involved in activation of sodium excretion?

Answer 3

SNS sends signal to

renin angiotensin system which releases ATII which stimulates

aldosterone release in adrenal gland

Question 4

End effect of sodium excretion regulation

Answer 4

Afferent efferent arteriolar GFR control

Tubular sodium reabsorption (inhibited by diuretics)

End effect to regulate sodium excretion

Question 5

What factors increase sodium reabsorption?

Answer 5

Aldosterone*
Renal sympathetic nerves
Angiotensin II
Argimine Vasopressin (ADH)

Question 6

What is the most important regulator of renal sodium excretion?

Answer 6

Aldosterone

Question 7

The factors that enhance sodium reabsorption are elicited by

Answer 7

Hypovolemia (if low volume, want to increase volume by increasing sodium)

Question 8

Aldosterone mainly acts where?

Answer 8

Principal cells of cortical collecting duct

Question 9

What receptor does aldosterone bind to?

Answer 9

Mineralocorticoid receptor

Question 10

What 3 things does aldosterone cause

Answer 10

1) synthesis and insertion of new Na/K ATPase
2) synthesis and insertion of new epithelial Na channels (ENaC) in apical membrane
3) stimulates ATP production (which increases mito size)

Question 11

What stimulates aldosterone secretion?

Answer 11

High plasma K+, ATII

Question 12

How does aldosterone increase sodium reabsorption?

Answer 12

Activates transcriptional events

Question 13

What does adrenal insufficiency lead to?

Answer 13

(Is Addison’s disease / lack of aldosterone)

Leads to depletion, ECF contraction, and circulatory insufficiency

Question 14

What does the renal sympathetic nerve release and activate?

Answer 14

Release NE which acts on α adrenergic receptors on proximal tubule cells

Activates

• apical Na-H exchanger
• bask lateral Na/K ATPase

Question 15

What does ATII do to renal sodium reabsorption?

Answer 15

Increases activity of

• Na-H in apical of proximal tubule
• Na-H in apical of TAL
• NaCl cords sported in early distal
• ENaC in late distal tubule and principal cells in collecting tubule
• also stimulates aldosterone secretion

Question 16

How does arginine vasopressin (ADH) increase sodium reabsorption?

Answer 16

Increases activity of

• Na/K/2Cl in TAL
• ENaC in principal cells

Question 17

Proximal tubule is affected by

Answer 17

SNS

ATII

Question 18

TAL affected by

Answer 18

ATII

AVP

Question 19

Distal tubule affected by

Answer 19

ATII

Question 20

Principal cells affected by

Answer 20

Aldosterone (mainly)
ATII
AVP

Question 21

4 things that increase sodium excretion

Answer 21

ANP
PGs & bradykinin
NO