Question

6. Concerning potassium.

a. What is the normal range for plasma potassium?

b. Why is maintaining potassium in this range so important?

c. How is plasma potassium concentration controlled in the short term (secs) and in the long term (minutes to hours)?

Please give a detailed answer. Add supportive equations or flow diagrams if possible.

Answer 1

a. Normal potassium ion concentration on blood is about 3.5 to 5 mEq/litre.

B. Potassium is one of the most important element in the body. The sodium potassium pump is the main operating system which control the nerves and muscles function. The cardiac cells also require potassium ions for generation and propogation of action potential.

Potassium is also important for maintaining acidbase and ionic balance in body.

Potassium is also important for synthesis of ribosomes for synthesis of proteins.

C. The short term regulation of potassium occur by either influx or efflux of potassium into the cells according to the need. The transmembrane potassium flux channel present in cells help in maintaining potassium level. When there is potassium deficit inside cell, then there is influx of potassium ions into the cells .

The long term regulation of potassium occur by aldosterone hormone. Aldosterone increases potassium excretion through the renal tubules. When aldosterone is deficient, the potassium ion concentration in ECF increase leading to hyperkalemia.

When potassium level in blood are low, the aldosterone release is suppressed from the adrenal gland as aldosterone excrete potassium.

And when potassium level are high, aldosterone is released more so that potassium is excreted more from renal tubules.