Blood Physiology PDF

Physiological aspects of blood Prof. DR. Mervat El-Saka  Blood ❑ It is viscous fluid. ❑ It is considered as a special type of connective tissue ❑ It circulates within the cardiovascular system ❑ Blood consists of cells suspended in a clear yellowish fluid called the plasma. ...

Physiological aspects of blood Prof. DR. Mervat El-Saka  Blood ❑ It is viscous fluid. ❑ It is considered as a special type of connective tissue ❑ It circulates within the cardiovascular system ❑ Blood consists of cells suspended in a clear yellowish fluid called the plasma.  Composition of blood 55% plasma 45% cells The platelets The red blood (thrombocytes). cells The white blood (erythrocytes). cells (leukocytes). PHYSICAL PROPERTIES OF THE BLOOD Arterial blood is Venous blood is bright red dark red ❑ It means that fluids resist change in their shape ❑ viscosity of blood is five times as the viscosity of water (a) Crystalloid osmotic pressure: It is not effective in water absorption. It is about 4000mm/Hg It created by crystalloids (electrolytes) (b) Colloid osmotic pressure: It is due to plasma proteins it is 30mmHg. It is effective in water absorption. It is created mainly by albumin. Osmosis  As blood passes through capillaries… Fluid filters from plasma Fluid is reabsorbed from to interstitium interstitium into plasma  PH The PH of arterial blood is 7.4 The PH of venous blood is 7.3  globulins Alpha 1 and 2, Types Albumin beta1 and 2 and Fibrinogen Prothrombin gamma globulins. 200 - 400 % 4-4.5 gm % 2.5 – 2.7 gm%. 10 mg%. mg%. M.W 70000 90000- 200000 400000. 69000. Liver except γ globulins Site of synthesized in liver liver Liver formation lymphoid tissues by plasma cells Blood Maintaining Main Defense clotting Blood plasma function function Blood clotting colloidal. viscosity  Main functions of plasma proteins 1- Nutrition: Plasma proteins are used in protein metabolism. 2- Blood clotting: Fibrinogen and prothrombin are essential for coagulation of the blood 3- Viscosity: By fibrinogen and globulins. 4- Important for ESR: ESR is dependent on fibrinogen and globulins. Suspension of erythrocytes  Main functions of plasma proteins 5- Immunity: Gamma globulins used to exert passive immunity. 6- Carrier: ✓ Plasma proteins carry e.g. hormones, thyroxin, vitamin A & minerals. ✓ So preventing their rapid elimination in the urine. 7- Capillary permeability: Plasma proteins close pores in cement substance. So, they maintain normal capillary permeability.  Main functions of plasma proteins 8- Buffering action: They behave as weak acids bind with (Na) in alkaline pH of the blood. 9- Osmotic pressure: Mainly by albumin due to: A- Its high concentration. B- Its small molecular weight. Osmotic pressure of plasma proteins is important for reabsorption of fluids from tissue spaces at capillary venous end by antagonizing the filtering force of capillary blood pressure.  Albumin Albumin/ Globulin ratio = A/G ratio Normally A/G ratio is about 1.2 to 1.6. Globulin A/G ratio is decreased in A/G ratio is increased in 1- Decreased albumin formation as in liver Decreased gamma globulins diseases. (Congenital 2-Increased albumin loss as in kidney diseases. Agammaglobulinemia) 3-Infections due to increased formation of immunoglobulins (γ globulin).