What role does haemoglobin play in the circulatory system?

Haemoglobin plays a crucial role in the circulatory system by transporting oxygen from the lungs to the tissues and organs throughout the body. It is a specialized protein found in red blood cells, allowing them to carry oxygen efficiently. When inhaled air reaches the lungs, oxygen diffuses into the bloodstream and binds to haemoglobin molecules, forming oxyhaemoglobin. This complex is then transported via the bloodstream to various cells where oxygen is released for cellular respiration, a process essential for producing energy in the form of ATP.

Haemoglobin's ability to pick up and release oxygen is vital for maintaining the metabolic needs of cells; it ensures that all body tissues receive adequate oxygen supply. While haemoglobin can also play a role in transporting carbon dioxide back to the lungs for exhalation, its primary and critical function is the transport of oxygen.