LO5: RBC Life Cycle

Where are erythrocytes produced?

In the red bone marrow through the process called erythropoiesis.

What stimulates erythropoiesis?

The hormone erythropoietin (EPO), released by the kidneys in response to low oxygen levels.

How long does it take for a red blood cell to mature from a stem cell?

Approximately 5 days.

How long do mature erythrocytes live in circulation?

About 120 days.

Why do erythrocytes have a limited lifespan?

Because they lack a nucleus and most organelles, limiting their ability to repair themselves.

How are old or damaged erythrocytes removed from circulation?

They are broken down by macrophages in the spleen, liver, and bone marrow.

What happens to the components of erythrocytes after they are broken down?

• Hemoglobin is separated into heme and globin.

• Globin proteins are broken down into amino acids and recycled.

• Iron from heme is stored or transported bound to transferrin for reuse.

• The rest of the heme is converted into bilirubin for excretion.