Red Blood Cells and Hemoglobin Functions

Study Notes

Red Blood Cells (Erythrocytes)

Red blood cells, also known as erythrocytes, are anucleated cells, except in camels.
They are biconcave discs with a size of 7-8 µm (7.5 µm).
Red blood cell lifespan is approximately 120 days.
They have a salmon-red color.
Normal red blood cell counts range from 4-6 million per mm³ of blood, with males averaging 5,000,000/mm³ and females averaging 4,000,000/mm³.
The formation of red blood cells, known as erythropoiesis, is dependent on Vitamin B12 and B2.
The destruction of red blood cells is called hemocateresis.
Hemoglobin, which makes up 33% of the blood volume, is responsible for gas transport.
- Hemoglobin is composed of heme and globin chains (α - β 141aa - 146aa chains).
- Iron (Fe2+), located in the heme group, is crucial for oxygen transport.
- When iron is in the Fe3+ (Ferric) state, it is called methemoglobinemia.

Hemoglobin Function

Hemoglobin binds to oxygen, carbon dioxide, and carbon monoxide.
- Oxyhemoglobin is formed when hemoglobin binds to oxygen.
- Carboxyhemoglobin is formed when hemoglobin binds to carbon monoxide.
- Carbaminohemoglobin is formed when hemoglobin binds to carbon dioxide.

Erythropoietin (EPO)

Erythropoietin (EPO) is a hormone produced in the kidneys.
It stimulates the production of red blood cells in the bone marrow.

Red Blood Cell Destruction and Recycling

Worn out or damaged red blood cells are phagocytized by macrophages, particularly Kupffer cells in the liver.
Hemoglobin is broken down into heme and globin.
Globin is recycled into amino acids used in protein synthesis.
Heme is converted into biliverdin, then bilirubin.
Iron (Fe3+) is released from heme and transported bound to transferrin.
Bilirubin is transported to the liver, where it is converted into urobilinogen.
Urobilinogen is converted into urobilin (in the kidneys) and stercobilin (in the intestine).
Urobilin is excreted in urine, while stercobilin is excreted in feces.
Iron (Fe3+) and amino acids from globin are recycled within the body.

Key Locations

Bone marrow: The site of erythropoiesis (red blood cell production).
Spleen: Responsible for removing old red blood cells from circulation.
Liver: Processes bilirubin produced during red blood cell breakdown.
Kidneys: Produce erythropoietin, a hormone crucial for red blood cell production.
Intestines: Excrete stercobilin in feces.
Macrophages: Phagocytic cells that engulf and break down old red blood cells.

Alterations in Red Blood Cells

Erythrocytosis: An increase in the number of red blood cells.
Anemia: A decrease in the number of red blood cells or the hemoglobin content.

Description

Explore the fascinating world of red blood cells (erythrocytes) and hemoglobin in this quiz. Test your knowledge on the structure, lifespan, formation, and functions of these crucial components of blood. Understand their role in gas transport and the importance of iron in oxygen binding.