Question

Mineral forming $90$% of the cations of blood plasma is

• A. $Mg$
• B. $Ca$
• C. $K$
• D. $Na$

Answer 1

The correct option is D $Na$

Sodium is the most abundant element in blood plasma while calcium is the most abundant element in the human body.

Mg forms an important constituent of chlorophyll. Magnesium is centrally located in the chlorophyll. It consists of porphyrin ring which has magnesium ion in the center.

Calcium is required for the contraction of muscles.

Potassium ions helps in the nerve transmission. For every three sodium ions two potassium ions are exchanged with the extracellular fluid.

Sodium is the most abundant mineral present in the extracellular fluid which helps in the nerve transmission. The sodium ions enters inside the nerve cell from the extracellular fluid and generates action potential. It leads to change in electrical potential that occurs across a plasma membrane during the passage of a nerve impulse. As, an impulse travels in a wave-like manner along the axon of a nerve, it causes a localised and transient switch in electric potential across the membrane from -60 mV to +45 mV. It is due to the fact that the sodium channels open and the potassium channels remain closed.

So, the correct answer is option D.