RBC Physiology
Specialized for their oxygen transport function. No nucleus or organelles = more room inside for hemoglobin and oxygen No mitochondria – ATP production is anaerobic ; therefore, they use none of the oxygen they transport Hemoglobin carries oxygen to body cells and transports ~ 23% of the total carbon dioxide where it is transported back to the lungs and exhaled
RBC Lifecycle
Lifetime = 145 days, without a nucleus or organelles there is no repair processes. Ruptured/old worn out RBCs are removed from circulation and destroyed by fixed phagocytic macrophages in the spleen and liver. Breakdown products are recycled. Hematocrit : the percentage of RBCs within total blood volume (ex: a hematocrit value of 60 means 60% of the total blood volume is composed of RBCs) Hematocrit norms: between 32% and 52% but can be as high as 60-70% in thoroughbred racehorses. Anemia : a significant drop in hematocrit. This reduces the bloods ability to carry oxygen to the body tissues. Polycythemia : an abnormally high hematocrit. This increases the viscosity of blood and ultimately makes the blood harder to pump by the heart.
Erythropoiesis: Production of RBCs
Production of RBCs begins in the red bone marrow with a precursor cell called a Proerythroblast . This cell divides several times and eventually ejects its nucleus to become a reticulocyte. Reticulocytes have some mitochondria, ribosomes, and ER. From the red bone marrow reticulocytes pass into the bloodstream and within 1-2 days they develop into mature RBCs.
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