Blood PDF - Medical Physiology

Blood By Sally Anwar Sayed Assistant Professor of Medical Physiology Faculty of Medicine - Assiut University Objectives:  To demonstrate the composition and functions of the blood.  To know the plasma proteins and their functions.  Clarify the blood...

Blood By Sally Anwar Sayed Assistant Professor of Medical Physiology Faculty of Medicine - Assiut University Objectives:  To demonstrate the composition and functions of the blood.  To know the plasma proteins and their functions.  Clarify the blood coagulation and their factors.  Know the difference between extrinsic and intrinsic mechanisms.  Clarify platelets and their functions  Know disorders of bleeding.  Demonstrate functions of spleen Reference: -The Human body in Health and disease Kevin T. Patton 6th edition Blood consists of plasma and cells (Red cells, white cells and platelets. Plasma: It is the portion of the blood 90 % water 0.9% inorganic constituents 7.1 % plasma proteins 2 % nutrient material and waste produce. Origin of plasma proteins: a) Tissue proteins b) Diet proteins Functions of plasma proteins: 1) Tissue metabolism. 2) Blood coagulation: Fibrinogen 3) Regulation of blood volume, tissue fluid formation and urine volume: plasma proteins (albumin) normally have osmotic pressure effect of 25 mmHg 4) viscosity of the blood: Fibrinogen 5) Buffer action 6) Immunity: gamma globulins 7) Transport function 8) Maintenance of capillary permeability  Hemostasis and blood coagulation  Hemostasis means prevention of blood loss and maintenance of normal blood volume.  Whenever a blood vessel if damaged, hemostasis is achieved by several mechanisms including.: A) Vascular spasm:  Local myogenic action.  Liberation of serotonin by platelets. B) Formation of platelet plug. C) Blood coagulation:  Formation of prothrombin activator.  Prothrombin activator catalyzes conversion on prothrombin into thrombin.  Thrombin converts fibrinogen into fibrin threads to form the clot itself. Platelets:  They are fragments of megakaryocytes which are giant cells present in the bone marrow  Platelet number is 200.000 to 400.000 / mm3 Functions: 1) Hemostasis 2) Blood clotting 3) Clot retraction 4) Phagocytosis 5) Storage of serotonin Abnormalities of Hemostasis: 1.Vitamin K deficiency causes depression in formation of prothrombin 2.Hemophilia is a disease characterized by defect in blood coagulation. 3.Thrombocytopenic purpura maintenance of very low number of platelets. Function of Spleen:  Blood formation.  Blood destruction  Defense reaction  Reservoir of the blood