06.2 Control of Potassium

Question 1

As the ECF [K+] increases what happens to the resting membrane potential of cells?

Answer 1

Increases (becomes less negative)

Question 2

What are the two processes that regulate potassium concentration?

Answer 2

Internal balance - shifts K+ between ICF and ECF

External balance - renal secretion

Question 3

By what transporter is potassium moved into cells?

Answer 3

NaKATPase

Question 4

How is potassium removed from cells?

Answer 4

Potassium channels

Question 5

What hormones increase the uptake of potassium into cells?

Answer 5

Insulin.
Aldosterone.
Catecholamines.

Question 6

What acid base state increases the uptake of potassium into cells?

Answer 6

Alkalosis.

Question 7

Name some factors that can cause potassium to leave cells.

Answer 7

Exercise.
Cell lysis.
Acidosis.
Increases ECF osmolarity.

Question 8

What factors in a diabetic can cause them to become hyperkalaemic?

Answer 8

Decrease in insulin.
Decrease in pH.
Increase in plasma tonicity.

Question 9

What acid base balance problems can hyperkalaemia and hypokalaemia cause?

Answer 9

Acidosis and alkalosis respectively.

Question 10

As the ECF [K+] decreases what happens to the resting membrane potential of cells?

Answer 10

The resting membrane potential will drop and become hyperpolarised.

Question 11

Where is the majority of potassium reabsorbed in the kidneys?

Answer 11

PCT

Question 12

What cells secrete potassium in the kidneys?

Answer 12

Principle cells.

Question 13

Where are principle cells located?

Answer 13

DCT + CD

Question 14

How do principle cells secrete potassium?

Answer 14

NaKATPase on the basolateral membrane.

Na+ and K+ channels on the apical membrane.

Question 15

What does an increase in ECF [K+] do to the tubule?

Answer 15

Stimulates NaKATPase on the basolateral membrane.

Stimulates aldosterone.

Question 16

What does aldosterone do to potassium levels?

Answer 16

Causes them to decrease as aldosterone stimulates, NaKATPase and K+ and Na+ channels on principle cells.

Question 17

How does an increased distal tubular flow rate impact potassium levels?

Answer 17

Increases potassium loss

Question 18

What membranes can the change in potassium levels alter?

Answer 18

Cardiac conduction
Cardiac pacemaker
Neuronal function
Skeletal muscle function
Smooth muscle function

Question 19

What can hyperkalaemia do to the heart?

Answer 19

Arrhythmia
Heart block

These can lead to a cardiac arrest

Question 20

How can hyperkalaemia affect the GI system?

Answer 20

Paralytic ileus.

Question 21

How can you treat hyperkalaemia?

Answer 21

Glucose + insulin.
Calcium gluconate to reduce the impact of potassium on the heart.
Remove excess potassium via dialysis.

Treat the cause - stop K+ sparing diuretics, treat diabetes etc.

Question 22

What can cause hypokalaemia?

Answer 22

Diarrhoea/vomiting
Certain diuretics
Increased aldosterone

Question 23

What are the cardiovascular features of hypokalaemia?

Answer 23

Arrhythmias

Question 24

What are the GI features of hypokalaemia?

Answer 24

Paralytic ileus.