Question

Short / long answer type questions.
In what different forms the $C{O}_2$ produced in the tissues is transported by the blood up to lungs. Explain the steps of release of this $C{O}_2$ into lungs for, exhalation.

Answer 1

Carbon-dioxide is transported in 3 processes:

1. About 5 to 8 percent of carbon dioxide is transported by dissolving in the blood plasma.

2. Carbon-dioxide bind to haemoglobin to form carbaminohaemoglobin. Haemoglobin is a blood pigment found in red blood cell that helps in transport of oxygen and carbon dioxide in the blood.

3. Most of the carbon dioxide is transported in the form of bicarbonate ions. First of all, carbon-dioxide diffuses into the red blood cells and is converted into carbonic acid by an enzyme carbonic anhydrase. Carbonic acid immediately dissociates into bicarbonate and hydrogen ions. The bicarbonate ion formed is exchanged from the red blood cells with chloride ions. This is known as the chloride shift. When blood reaches the lungs, the bicarbonate ion which is expelled from the red blood cells and binds with hydrogen ion to form carbonic acid which is converted back to carbon dioxide via carbonic anhydrase and exhaled.