Erythropoiesis and Factors Affecting Red Blood Cell Formation

Erythropoiesis

• During embryonic life, erythropoiesis occurs in the yolk sac, liver, and spleen
• Erythropoietin production is stimulated by low oxygen levels in the body

Erythropoietin

• The kidneys are responsible for producing most erythropoietin
• When O2 transport to tissues rises above normal, the rate of erythropoietin formation decreases
• Erythropoietin is the major regulating factor for erythropoiesis

Red Blood Cell Production

• Following hemorrhage or altitude change, the red bone marrow is stimulated to increase the rate of RBC production by low oxygen levels
• Erythropoietin, vitamin B12, and folic acid are necessary for the development and maturation of erythrocytes
• Hemoglobin accounts for 20-25% of total CO2 transport

Red Blood Cells

• The main function of red blood cells is to transport oxygen from the lungs to the body's tissues
• The lack of a nucleus in mature red blood cells allows for more space for hemoglobin, increasing oxygen transport efficiency
• Hemoglobin is the component of red blood cells that facilitates oxygen transport
• Red blood cells pick up oxygen in pulmonary capillaries
• In systemic capillaries, hemoglobin releases oxygen to the tissues

Hemoglobin

• The normal range for hemoglobin in adults is 13.5-17.5 g/dL for men and 12-16 g/dL for women
• Hemoglobin is responsible for 98-99% of oxygen transport
• The percentage of red blood cells in relation to whole blood is known as hematocrit
• Hemoglobin is a protein that gives red blood cells the ability to carry oxygen
• Intrinsic factor is necessary for vitamin B12 absorption, which is stored in the liver after absorption
• Iron and protein are crucial for hemoglobin formation
• Animal proteins are considered superior in the production of hemoglobin because they contain all essential amino acids
• Copper plays a role in hemoglobin synthesis by facilitating the incorporation of iron into heme
• Each hemoglobin molecule can contain 4 heme fractions
• The average concentration of hemoglobin in men is 15 g/dL

Hemoglobin Function

• The primary function of hemoglobin is to transport oxygen from the lungs to the body's tissues
• Carboxyhemoglobin is a derivative of hemoglobin formed by the combination of hemoglobin with CO2
• In methaemoglobin, the iron is oxidized to the ferric state
• Erythropoietin stimulates the production of red blood cells by promoting the proliferation and differentiation of erythroid progenitors
• Hemoglobin has a higher affinity for CO2 than O2
• Thyroid and androgen hormones are required for erythropoiesis due to their promotion of tissue metabolism
• In oxyhaemoglobin, the iron is in the ferrous state
• Vitamin C is necessary for the formation of hemoglobin by facilitating the absorption of iron
• A healthy liver is essential for normal red blood cell formation because it stores vitamin B12 and produces intrinsic factor
• Carboxyhemoglobin can still carry oxygen despite exposure to drugs and oxidizing agents
• The bone marrow is responsible for the production of red blood cells
• When oxygen is released from oxyhaemoglobin, hemoglobin is in the deoxyhaemoglobin form
• Vitamin B12 and folic acid are essential for the maturation of red blood cells because they are necessary for DNA synthesis
• The main feature of hemoglobin in relation to oxygen binding is its sigmoidal binding curve
• The main source of vitamin B12 is animal products, such as meat, fish, and dairy products
• In a normal person, 19.2 mL of oxygen can be carried in combination with hemoglobin in each 100 mL of arterial blood

Aplastic Anemia

• Aplastic anemia occurs as a result of a failure of the bone marrow to produce red blood cells