Red Blood Cell Life Cycle

Summary

This transcript outlines the intricate lifecycle of red blood cells, starting with their breakdown into components by phagocytosis in the spleen, liver, or bone marrow. The protein (globin) is broken down into amino acids, while the heme is split into iron and bilirubin. The iron is transported through the blood by transferrin to be stored in the liver or muscle, while the bilirubin is processed by the liver and excreted as bile. The iron is eventually reused in the formation of new red blood cells, completing a cycle that lasts about 120 days. This process ensures a continuous supply of red blood cells in circulation.

Takeaways

• 😀 Red blood cells are broken down by phagocytosis in the spleen, liver, or bone marrow, starting the breakdown process.
• 😀 Hemoglobin is divided into two components: the protein globin, which is broken down into amino acids, and the non-protein heme.
• 😀 The amino acids from globin are reused for protein synthesis, while the heme is broken down into iron and bilirubin.
• 😀 Iron from the heme is transported in the blood via transferrin to the liver or muscle, where it binds to ferritin for storage.
• 😀 When needed, the stored iron is released from the liver or muscle, bound to transferrin, and transported to the red bone marrow.
• 😀 In the red bone marrow, iron and globin recombine to form hemoglobin, and new red blood cells are produced by erythropoiesis.
• 😀 The non-iron part of the heme is converted into bilirubin, which is then transported to the liver.
• 😀 Bilirubin is excreted in bile, which travels to the small intestine, where bacteria convert it into urobilinogen.
• 😀 Urobilinogen has two potential fates: it can be converted into stercobilin and excreted in the feces, or enter the bloodstream.
• 😀 Urobilinogen that enters the bloodstream is filtered by the kidneys, converted into urobilin, and excreted in urine, giving urine its yellow color.
• 😀 The entire process of red blood cell breakdown and renewal forms a cycle that lasts about 120 days, after which new red blood cells are produced.

Q & A

What happens to red blood cells when they are broken down?

Red blood cells are broken down by phagocytosis in the spleen, liver, or bone marrow into their component parts, which include globin (a protein) and heme (a non-protein component).

What are the two main components produced after the breakdown of red blood cells?

The two main components produced after red blood cell breakdown are globin, a protein, and heme, a non-protein component.

What happens to the globin after red blood cell breakdown?

The globin is broken down into amino acids, which are then reused for protein synthesis.

What happens to the heme after red blood cell breakdown?

The heme is broken down, and the iron is released from it. The iron is then transported in the blood via transferrin.

How is the iron from the heme transported in the body?

The iron is transported in the blood via transferrin, which carries it to the liver or muscles where it is stored as ferritin.

What happens when the body needs the stored iron?

When the body needs iron, it is released from storage, recombines with transferrin, and is transported back to the red bone marrow for red blood cell production.

What is the role of transferrin and ferritin in iron transport and storage?

Transferrin is responsible for transporting iron in the blood, while ferritin is used for storing iron in the liver and muscles.

What happens to the non-iron component of the heme?

The non-iron component of the heme is converted into bilirubin, which is then transported to the liver.

What is the fate of bilirubin after it is produced?

Bilirubin is transported to the liver, where it is released as bile into the small intestine. It can be converted into urobilinogen by bacteria, which can either be excreted as stercobilin in feces or be transported to the kidneys and excreted in urine as urobilin.

What causes urine to have a yellowish color?

The yellowish color of urine is caused by the conversion of urobilinogen into urobilin in the kidneys.