What is the oxygen carrying component of red blood cells?

Hemoglobin is the oxygen-carrying component of red blood cells, consisting of a protein called globin and an iron-containing heme group. Each hemoglobin molecule can bind to four oxygen molecules, which allows for efficient transport of oxygen from the lungs to the tissues. This process is crucial for maintaining cellular respiration and overall metabolic function in the body.

Myoglobin, while also an iron-containing protein, is found in muscle tissues and serves to store oxygen rather than transport it like hemoglobin. Fibrinogen and thrombin are involved in the blood coagulation process, neither of which has a role in oxygen transport. Therefore, hemoglobin's unique structure and function are pivotal for the primary task of oxygen delivery in the circulatory system.