RED BLOOD CELLS

BLOOD: Connective tissue. O 2 from lungs to body tissues. CO 2 from body tissues to lungs. Fluid of growth: nutritive substances from digestive system. Hormones from endocrine system. Fluid of health: Protection against disease. Removal of waste products.

Properties of blood: Color: Arterial blood scarlet red. Venous blood is purple red. Volume: 5L average in normal male adults. 4.5 L in females. 450ml in new born baby. pH: Slightly alkaline. 7.4 pH. Viscosity: 5 times viscous than water.

Composition of blood: Blood cells and plasma. Three types of cells: RBCs or erythrocytes. WBCs or leukocytes. Platelets or thrombocytes.

Serum : Straw coloured fluid that oozes from blood clot. during clotting, fibrinogen is converted into fibrin and blood cells are trapped in fibrin. serum than oozes out. volume of serum is 55%. different from plasma by absence of fibrinogen. Plasma: Straw coloured clear liquid part of blood. 91% - 92% water. 8% - 9% solids. ( organic and inorganic substances)

Functions of blood: Nutritive functions: Glucose, amino acids, lipids and vitamins. Respiratory function. Excretory function: Removal of waste products. Transport of hormones and enzymes: Regulation of water balance: Water content is interchangeable with interstitial fluid. Regulation of acid base balance: Plasma proteins and haemoglobin act as buffer. Regulation of body temperature: Specific heat of blood. Thermoregulatory mechanism. Storage function. Defence function.

RED BLOOD CELLS/ ERYTHROCYTES: Non nucleated cells. No DNA. No mitrochondria and golgi apparatus. Energy from glycolytic process. Haemoglobin. Biconcave disc. 7.8 micrometer diameter. 2.5 micron at thickest point. 1 micrometer in centre. Average volume is cubic micrometer. Shape is modifiable. Concentration of RBCs: 5 million in males. 4.5 million in females.

Hematocrat value: Plasma forms 55% of blood RBCs form 45% of blood. Hematocrat is percentage of blood that is cell. Or Volume of RBCs expressed in percentage. It is also called packed cell volume. 15 gm of Hb/100 ml of cells in males. 14 gm of Hb/100 ml of cells in females. 1 gm Hb combine with 1.34 ml of oxygen. 100ml of blood can carry 20 ml of oxygen.

Quantity of haemoglobin in the cells: 34 grams in 100 ml of cells. Metabolic limit. Normocytic: normal volume/ size of cells. Macrocytic: increased volume/ size of cells. Microcytic: decreased volume/ size of cells. MCHC: mean corpuscular haemoglobin concentration. Normochromic: normal haemoglobin in cells. Hypochromic: decreased haemoglobin in cells. Hyperchromic: increased haemoglobin in cells.

Production of RBCs: Areas where RBCs are formed: Embryonic life: primitive nucleated cells are formed in yolk sac. 2 nd trimester of gestation: Liver main organ. Spleen and lymph nodes. Last month and after birth: Bone marrow. Bone marrow of all bones untill 5 years. Long bones become fatty and no RBC production in about 20 years. Except proximal ends of humerus and tibia. After 20, RBC production by membranous bones i.e vertebrae, sternum, ribs and ilia Marrow becomes less productive with age in these bones