Blood
Blood = connective tissue Extracellular matrix: Plasma (55%) specialized cells (45%) (= Formed elements) *- erythrocytes (red blood cells) *- leukocytes (white blood cells) *- thrombocytes (platelets)
Physical properties: (1) Colour: red (2) pH: 7.4 (7.35-7.45) (3) Specific gravity: 1.052-1.061 plasma = 1.030 & of RBCs = 1.090. (4) Viscosity: about 5 times as water (5) Osmotic pressure: 5100-5500 mmHg = 0.9% gm NaCl = 300 milliosmol/ liter
Functions of Blood Transports: Regulation: Defense: Maintains Nutrients water content Foreign organisms Electrolytes pH Injury/infection O2 & CO2 Body temperature Waste Products Clotting process Hormones Arterial bl. pressure Maintains Homeostasis
Plasma Water about 90% Plasma proteins 7.1-7.4% Volume: 5% of body wt. – 3.5 liter in adult 70 kgm Transports organic and inorganic molecules, formed elements, and heat Water about 90% Plasma proteins 7.1-7.4% Inorganic constituents 0.9% Other solutes 2% (Nutrients, hormones, waste products & enzymes
Plasma Proteins Albumin Globulin Fibrinogen Prothrombin - Value - M.W 3.5-5 gm% 2.3-3.5 gm% 200-400mg % 10-15 mg % - M.W 70.000 150.000 340.000 69.000 -Synthesis Liver Liver1, 2, 1, B2 types RES type - Main -Transporter -Carrier -Viscosity Act as clotting function -Osmotic pres. regulation -Defensive (see below) -Bl. Clotting (factor I) factor II
* Functions of plasma proteins 1) Blood clotting (haemostasis) 2) Defense (immunity) 3) Transport function 4) Regulation of body fluids 5) Regulation of plasma viscosity 6) Control of capillary permeability 7) Buffer functions Hormones and enzymes 8) Nutritional functions 9) CO2 carriage 10) Specific functions
* Separation of plasma proteins: 1)Plasma ultracentrifugation (a) Salting out technique: 2) Chemical separation: (b) Fractional precipitation 3) Electrical separation: (electrophoresis) * Sources of plasma proteins 1) Food proteins 2) Tissue proteins: (a) Reserve (b) Fixed
* Dynamic state of plasma proteins Plasma proteins are continuously destroyed and reformed in the liver in equal rate constant level (5-10% of albumin is destroyed & reformed/day). * Plasmapheresis It is experiment to study the rate of synthesis of the plasma prot. and factors affecting it.
* Hypoproteinemia: Definition: it is marked decrease in plasma proteins. Causes: 1- Prolonged starvation 2- Malabsorption. 3- Decrease synthesis as in liver diseases (cirrhosis). 4- Increase loss as in kidney diseases (nephrosis). 5- Congenital afibrinogenaemia. Effect: -Decrease albumin decrease osmotic pressure oedema. Also oedema caused by increase capillary permeability. - Decrease globulin decrease immunity. -Decrease fibrinogen & clotting factors bleeding tendency.
* Albumin/globulin ratio (A/G ratio): - It is about 1.2-1.7 - It decreases in: (1) Liver diseases (2) Kidney failure or nephrosis (3) Infections
Differences between plasma and serum: - Obtained by centrifugation of blood sample after adding of anticoagulant. - Obtained by centrifugation of clotted bl. sample - Contains plasma proteins and clotting factors - Contains plasma proteins but no clotting factors I, II, V & VIII (consumed in bl. clotting) - Clot on standing - Not clot on standing - Normal serotonin level - Serotonin from broken platelets with blood coagulation
Blood volume about 5 litres (3 L. plasma & 2 L RBCs) = 8% of body weight. less in females and obese fatty person Distribution *- 55% in veins *- 7% of the blood in the heart *- 18% in pulmonary system *- 15% in arteries *- 5% in capillaries Variations in blood volume Blood volume increases in : 1-Physiological causes -Pregnancy -High altitude -Muscular exercise 2-Pathological conditions: - Over transfusion of blood or I.V fluids - Polycythaemia vera Blood volume decreases in: - Dehydration - Haemorrhage
*Measurement of blood volume -The blood volume = plasma volume + RBCs volume Dilution principle (Dye method) A known amount of a test substance or dye (C1 x V1) is injected in blood, then 10 min. are allowed for uniform Distribution in the blood, then blood volume (V2) is calculated from the degree of dilution of the tested substance (C2). As C1 x V1 = C2 x V2 V2 = C1 x V1 / C2 The test substance must be: not metabolized – non toxic – easily determined. - does not leave the circulation to urine or tissue The substance that used to measure plasma volume should combine to plasma proteins as Evan’s blue dye or radio- active iodine125.
The substance used to measure RBCs volume must enter the cells as isotopic chromium (Cr51) Chromium is mixed with few cm of blood for half an hour , chromium which enter RBCs is determined by Geiger counter Then the radio-active RBCs are reinjected I.V. After 10 min blood sample is obtained and RBCs are separated and the new chromium concentration is determined and the volume of RBCs can be determined Blood volume = Plasma volume x = RBCs volume x Isotope method By using known amount of albumin labeled with isotopic iodine in the dilution principle. A Gamma counter measures this amount