Examville.com - Physiology -erithrocytis Or Red Blood Cells

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ERYTHROCYTES OR RED BLOOD CELLS (RBCS) RBC is a circular, biconcave, non nucleated disc. Life span of RBCs is 120 days. Size of RBC -6.5 -8.8 micron The central part of RBC is thinner then the circumference

RBC Count: At birth: 6-8 million/cumm Adults: 5-6 million/cumm Females 4.5- 6 million/cumm

FUNCTIONS z Transport of oxygen. z Helps in identifying the blood groups.

RBC indices: 1. MCV volume of RBC in cubic microns.(Normal range 78 – 94 cubic microns) < 78cubic micron -microcytes, > 94 cubic micron macrocytes. 2. MCH: Amount of hemoglobin in a single RBC in pico gm. Normal range: 28 -32 pg. 3. MCHC: Concentration of hemoglobin in a single RBC (NORMAL -32-35%) MCHC < 33% HYPOCHROMIC RBC NOTE: MCHC is never greater than 38% as RBC can not carry Hb beyond their saturation point. Thus anemia can never be hyperchromic

HAEMOPOIESIS It is the development of the blood cells ie. RBC, WBC and platelets ERYTHROPOIESIS Stages of erythropoiesis

STEM CELLS

PROERYTHROBLAST

EARLY NORMOBLAST

INTERMEDIATE NORMOBLAST

LATE NORMOBLAST

RETICULOCYTES

ERYTHROCYTES

CHANGES IN RBC DURING ERYTHRPOISIES 1. Reduction in cell size 2. Increased amount of cytoplasm 3. Basophilic cytoplasm changes to polychromatophilic and then acidophilic due to decreased content of RNA 4. Disappearance of nucleus

APPLIED

1. Anemia- When RBC counts are < 4 million/mm3 or Hb content <12gm % in females and < 13 gm % in males, then this condition is called anemia. Graded as: Mild Anemia 8 – 12 gm % Moderate Anemia - 5 – 8 gm% Severe Anemia - < 5 gm% 1. 2. 3. 4.

Based on cause anemia is divided into: Hemorrhagic anemia Hemolytic anemias Anemia due to dietary deficiency Aplastic anemia

Based on RBC size and hemoglobin concentration: 1. Megaloblastic anemias z Folic acid deficiency z Pernicious anemia. 2. Microcytic hypochromic anemia z Iron deficiency anemia z Thalassemia. Polycythemia: RBC COUNT > 6milllion/cumm. It is the condition characterized by excess number of RBC in the blood. PRIMARY POLYCYTHEMIA: Bone marrow is hyperplastic with increased number of RBC SECONDARY POLYCYTHEMIA: There is a compensatory increase in the red cells in chronic hypoxic conditions.