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Transcript
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 ml
of 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 regulator
of rbc production
b. Erythropoietin stimulates rbc production, and its
formation increases in response to hypoxia
c. Role of the kidney-90% of the erythropoietin is formed
in 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-leads
to pernicious anemia
c. Maturation failure with poor absorption of Folic acidleads to sprue (usually occurs in association with the
vitamin 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 rate
of 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 a
bluish cast