Potassium Balance

Question 1

About 98% of the body’s potassium is in the

Answer 1

ICF

Question 2

The potassium concentration outside the cell at any moment represents a balance between

Answer 2

1. The rate of gain across the digestive epithelium

2. The rate of loss into urine

Question 3

Potassium loss in urine is regulated by

Answer 3

Controlling the activities of ion pumps along the distal portions of the nephron and collecting system

Question 4

Whenever a sodium ion is reabsorbed from the tubular fluid it generally is exchanged for

Answer 4

A cation typically potassium from the peritubular fluid

Question 5

Urinary potassium losses are usually limited to the amount gained by absorption across the digestive epithelium typically

Answer 5

50-150 mEq (1.9 -5.8g) per day

Question 6

The rate of tubular secretion of potassium into urine varies in response to three factors

Answer 6

1. Changes in the potassium concentration of the ECF; higher extracellular concentration of potassium, the higher the rate of secretion.
2. Changes in pH. When the pH of the ECF decreases, so does the pH of the peri tubular fluid. The rate of potassium secretion then decreases, because hydrogen ions are secreted in exchange for sodium ions in tubular fluid.
3. Aldosterone levels. Hi plasma potassium concentrations stimulate aldosterone secretion. Angiotensin 2 stimulate aldosterone secretion. Under the influence of aldosterone the amount of sodium conserved and the amount of potassium excreted in urine are directly related.

Question 7

Hypokalemia

Answer 7

A deficiency of potassium in the blood stream

Question 8

Hyperkalemia

Answer 8

And elevated level of potassium in the blood stream

Question 9

Volume depletion

Answer 9

When water lost leads to an increase in the sodium concentration of the ECF. The water content of the ECF decreases as the water loss occurs, so blood volume decreases. Kidney function is impaired. As a result, wastes accumulate in the blood.