Unit Six: Blood Cells, Immunity, and Blood

Coagulation

Chapter 32: Red Blood Cells, Anemia, and Polycythemia

Guyton and Hall, Textbook of Medical Physiology, 12th edition

Red Blood Cells

• Red Blood Cells (Erythrocytes)

a. Transport hemoglobin

b. Contain carbonic anhydrase (acid-base buffering)

c. Shape and size of rbcs-pliable

d. Concentration in the blood- 40-45%

e. Quantity of hemoglobin in the cells- 14-15 g/100 mlof cells

Red Blood Cells

• Production of Red Blood Cells

Fig. 32.1 Relative rates of rbc production in the bone marrow of different bones at different ages

Genesis of Blood Cells

• Pluripotential Hematopoietic Stem Cells

Fig. 32.2

Genesis of Blood Cells

•Stages of Differentiation of RBCs

Fig. 32.3

Red Blood Cells (cont.)

• Regulation of RBC Production-Erythropoietin

a. Tissue oxygenation is the most essential regulatorof rbc production

b. Erythropoietin stimulates rbc production, and itsformation increases in response to hypoxia

c. Role of the kidney-90% of the erythropoietin is formedin the kidney (liver-10%)

Red Blood Cells (cont.)

Fig. 32.4 Function of the erythropoietin mechanism to increase production of rbcs when tissue oxygenation decreases.

Red Blood Cells (cont.)

• Maturation of RBCs

a. Requirement for Vitamin B12 and Folic acid

b. Maturation failure with poor absorption of B12-leadsto pernicious anemia

c. Maturation failure with poor absorption of Folic acid-leads to sprue (usually occurs in association with thevitamin deficiency

Red Blood Cells (cont.)

• Formation of Hemoglobin

Fig. 32.5 Formation of hemoglobin

Fig. 32.6 Basic structure of hemoglobin

Red Blood Cells (cont.)

• Iron Metabolism

a. Transport and storage of iron- transferrin, ferritin

b. Daily loss of iron (0.6 mg/day; feces)

c. Absorption of iron from the GI tract

d. Regulation of total body iron by controlling the rateof absorption

Red Blood Cells (cont.)

• Iron Metabolism

Fig. 32.7 Iron transport and metabolism

Red Blood Cells (cont.)

• Life Span of RBCs is about 120 Days

• Destruction of Hemoglobin

a. Fe is carried by transferrin to bone marrow

b. Fe is stored as ferritin

c. Porphyrin ring is converted to bilirubin

Anemias

• Blood Loss Anemia- hemorrhage

• Aplastic Anemia- lack of functioning bone marrow

• Megaloblastic Anemia- slow reproduction of erythroblasts

• Hemolytic Anemia- abnormalities of rbcs

• Effects on the Circulatory System- low blood viscosity,decreased resistance to blood flow, increased CO,increased workload on the heart

Polycythemia

• Secondary Polycythemia- abnormal quantities of rbcs

• Polycythemia vera (Erythremia)- genetic aberration

• Effects on the Circulatory System- CO and arterial pressure is normal, blood is sluggish passing through the capillaries and skin color may take on abluish cast