What change occurs in hemoglobin upon respiration?

Hemoglobin undergoes several changes during the process of respiration, specifically oxygen binding and release. These changes are crucial for transporting oxygen from the lungs to the tissues and facilitating cellular respiration.

1. Oxygen Binding (Oxygenation):

- In the lungs, hemoglobin binds to oxygen molecules to form oxyhemoglobin.

- Each hemoglobin molecule can bind to a maximum of four oxygen molecules, forming fully saturated oxyhemoglobin (HbO4).

- The binding of oxygen to hemoglobin is influenced by partial pressure of oxygen (pO2) in the lungs, which is relatively high.

2. Oxygen Release (Deoxygenation):

- As blood travels through the body's tissues, the partial pressure of oxygen decreases, creating a gradient.

- This gradient promotes the release of oxygen molecules from hemoglobin.

- The oxygen molecules diffuse out of the capillaries and into the surrounding tissues, where they are utilized for cellular respiration.

- Hemoglobin becomes deoxygenated and converts back to its original form.

These changes in hemoglobin's oxygen affinity are regulated by several factors, including partial pressure of oxygen, temperature, pH, and the presence of certain chemicals like carbon dioxide (Bohr effect).

The reversible binding and release of oxygen to hemoglobin allow for the efficient transport of oxygen through the bloodstream and ensure a continuous supply to tissues for cellular respiration.