Clase 32 Fisiología Sanguínea - Eritrocitos (IG:@doctor.paiva)

Physiology of Blood Cells

In this class, Eduardo discusses the physiology of blood cells, focusing on erythrocytes or red blood cells.

Generalities of Erythrocytes

• Erythrocytes, also known as red blood cells, transport hemoglobin carrying oxygen from the lungs to tissues.

• Erythrocytes are biconcave disks with specific dimensions and a resilient membrane.

• The concentration of red blood cells varies between men and women, with average values specified.

Production of Erythrocytes

• The production starts in early embryonic life and continues in various organs like the liver, spleen, lymph nodes, and bone marrow.

• Differentiation of red blood cells stems from pluripotential hematopoietic stem cells committing to specific cell lines.

Erythropoiesis Process

Eduardo delves into the process of erythropoiesis where stem cells commit to forming erythrocytes through specific stages.

Colony Forming Units

• Pluripotent stem cells form colony-forming units (CFU), leading to the production of erythrocytes exclusively.

Growth Inducers and Differentiation

• Growth inducers control cell growth while differentiation inducers regulate cell specialization during erythropoiesis.

Red Blood Cell Differentiation

• Under stimulation, CFU-E forms proerythroblasts that progress through basophil erythroblasts to orthochromatocytes with minimal hemoglobin accumulation.

Maturation of Red Blood Cells

Eduardo explains the maturation process from reticulocytes to mature erythrocytes within a defined timeframe.

Maturation Process

• Reticulocytes transition into mature erythrocytes after losing basophilic material and undergoing nuclear changes.

Regulation and Functionality

Hypoxia and Erythropoiesis

This section discusses the impact of hypoxia on erythropoietin production, erythrocyte formation, and the role of essential vitamins in erythrocyte maturation.

Hypoxia and Erythropoietin Production

• Hypoxia triggers increased erythropoietin production.

• Erythropoietin stimulates proerythoblasts in bone marrow for new RBC formation.

• Factors like low blood volume and anemia decrease oxygen concentration, leading to erythropoietin production.

Vitamin Requirements for Erythrocyte Maturation

• B12 and F9 vitamins are crucial for DNA synthesis in erythroblastic cells.

• Deficiency of B12 or F9 leads to macrocytes formation causing anemia.

Intrinsic Factor and Vitamin B12 Absorption

Focuses on intrinsic factor's role in vitamin B12 absorption for erythrocyte formation.

Intrinsic Factor Functionality

• Parietal cells produce intrinsic factor aiding B12 absorption in the gut.

• Intrinsic factor binds with B12 for absorption via pinocytosis into circulation blood.

Hemoglobin Formation Process

Details the stages of hemoglobin formation from protoporphyrin IX to heme binding with globin chains.

Hemoglobin Synthesis Steps

• Proerythroblastic stage initiates hemoglobin formation.

• Succinyl-CoA combines with glycine to form pyrrole molecules leading to heme synthesis.

Iron Metabolism and Hemoglobin Function

Explores iron's significance in hemoglobin synthesis and its distribution within the body.

Iron Importance

Iron Absorption and Storage

This section discusses the absorption, transportation, storage, and utilization of iron in the body.

Iron Absorption Process

• Iron is absorbed in the small intestine and transported in the blood by transferrin.

• : 1% of iron is in heme compounds intracellularly, while 0.1% binds to transferrin.

Iron Storage Mechanisms

• Excess iron is stored mainly in liver hepatocytes as ferritin.

• : Iron combines with apoferritin to form ferritin inside cells.

Storage Forms of Iron

• Ferritin stores iron and hemosiderin forms when iron levels are high.

• : Ferritin is storage iron; hemosiderin forms from hemoglobin decomposition.

Utilization and Loss of Iron

• Hemoglobin breakdown releases iron for reuse or storage.

• : Monocyte-macrophage cells store liberated iron mainly as ferritin for future use.

Impact of Gender on Iron Loss

• Men excrete about 0.6 mg/day of iron, while women lose more due to menstrual blood loss.

• : Women may lose around 1.3 mg/day on average due to additional menstrual loss.

Role of Transferrin in Iron Balance

• Apotransferrin binds with iron to form transferrin in plasma for transport where needed.

• : Apoferritin binds with iron to form ferritin within liver cells.

Erythrocyte Lifespan and Functionality

This section explores the lifespan, functions, and destruction process of erythrocytes (red blood cells).

Erythrocyte Lifespan Insights

• Erythrocytes circulate for about 120 days before being destroyed without a nucleus or mitochondria but containing essential enzymes.

• : Enzymes within erythrocytes maintain cell membrane pliability and prevent protein oxidation.

RBC Destruction Process

• Fragile erythrocyte membranes rupture during circulation, leading to self-destruction primarily in the spleen's red pulp region.