Potassium+ handling

Question 1

Where does bulk reabsorption of K+ reabsorbed

Answer 1

Proximal tubule

Question 2

what is the major influence on K+ excretion

Answer 2

Tubular secretion of K+

Question 3

What are major factors affecting renal K+ secretion

Answer 3

Aldosterone

Plasma [K+]

Question 4

How does aldosterone affect renal K+ secretion

Answer 4

Overall: increases K+ secretion

Increases Na+ reabsorption and so increases electronegativity of tubule lumen

This increases Na+/K+ ATPase activity which increases cell K+

This increases luminal K+ permeability (opens K+ channels)

Question 5

How does plasma {K+] affect renal K+ secretion

Answer 5

Overall: increases K+ secretion

Increases luminal K+ permeability

Increases Na+/K+ ATPase activity

This stimulates secretion of aldosterone

Question 6

What do K+ sparing diuretics do

Answer 6

Inhibit the sodium channels which reduce how much potassium gets secreted

Question 7

What other factors increase K+ secretion

Answer 7

Distal flow rate

Na+ reabsorption without Cl-

Question 8

What is K+ like in acidosis

Answer 8

Hyperkalaemia

Question 9

What is K+ like in alkalosis

Answer 9

Hypokalaemia

Question 10

How is K+ regulated in acidosis

Answer 10

Decreased sodium pump
Decreased apical membrane permeability to K+

Increased H+K+ATPase