Describe the transport of gases by blood.

The transport of gases by blood involves the movement of oxygen and carbon dioxide between the lungs and tissues of the body. Oxygen is carried from the lungs to the tissues by red blood cells, which contain a protein called hemoglobin that binds to oxygen molecules. When blood passes through the lungs, oxygen diffuses into the blood and binds to hemoglobin, forming oxyhemoglobin. This oxygenated blood is then pumped by the heart to the tissues where oxygen is released from hemoglobin and diffuses into the cells.

Carbon dioxide, a waste product of cellular metabolism, is carried from the tissues to the lungs by the blood. Carbon dioxide is transported in three forms: dissolved in plasma, bound to hemoglobin, and as bicarbonate ions. In the tissues, carbon dioxide diffuses into the blood and reacts with water to form carbonic acid, which dissociates into bicarbonate ions and hydrogen ions. The bicarbonate ions are carried in the plasma to the lungs, where they are converted back into carbon dioxide and exhaled.

Overall, the transport of gases by blood is essential for maintaining the balance of oxygen and carbon dioxide in the body and ensuring that cells receive the oxygen they need for energy production.