What is the primary of red blood cells?

The primary function of red blood cells, also known as erythrocytes, is to carry oxygen throughout the body. Here's a closer look at their role:

Oxygen Transport:

- Red blood cells contain a protein called haemoglobin, which is composed of four polypeptide chains called globins.

- Each globin chain has an iron atom bound to a porphyrin ring, known as a heme group.

- Oxygen molecules bind reversibly to the iron atoms in haemoglobin, forming oxyhaemoglobin.

Oxygen Delivery to Tissues:

- Red blood cells circulate throughout the bloodstream, carrying oxygenated haemoglobin from the lungs to various tissues and organs in the body.

- In the capillaries, the smallest blood vessels, where the exchange of gases occurs, oxygen diffuses out of the red blood cells and into the surrounding tissues.

Carbon Dioxide Transport:

- Red blood cells also play a role in transporting carbon dioxide, a waste product of cellular respiration, back to the lungs for elimination.

- Some carbon dioxide binds directly to haemoglobin, forming carbaminohaemoglobin.

- Additionally, carbon dioxide can react with water in the red blood cells to form carbonic acid (H2CO3).

Carbonic acid quickly dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-).

- Most of the carbon dioxide is transported as bicarbonate ions in the plasma.

Buffering Action:

- Haemoglobin in red blood cells acts as a buffer, helping to regulate the pH of the blood.

- Haemoglobin can bind hydrogen ions, reducing their concentration in the blood and preventing excessive acidity.

Role in Carbon Monoxide Poisoning:

- Carbon monoxide has a much higher affinity for haemoglobin than oxygen, forming a stable compound called carboxyhaemoglobin.

- Carboxyhaemoglobin reduces the oxygen-carrying capacity of red blood cells, leading to oxygen deprivation and potentially fatal consequences in cases of carbon monoxide poisoning.

Overall, red blood cells are essential for maintaining the body's oxygen supply and removing waste products like carbon dioxide. Any abnormalities in red blood cell count, haemoglobin levels, or haemoglobin function can lead to various blood-related disorders and health conditions.