Blood performs several vital functions of the body,hence it has been frequently referred to as the seat of the soul. It distributes nutrients, oxygen detoxicating compounds and maintains a uniform body temperature. It is a carrier of hormones which control and integrate the activities of the various organs. It conveys antibodies and cells that protect the body from invading pathogens and also transports drugs administered to the body so that they may produce their therapeutic effects on specific sites of ailments . The blood also collects the waste material generated by the body's metabolic activities.
The science dealing with the study of blood is referred to as hematology.
The blood can carry out its efficiently only if it is kept circulating in the body. This is effected by the heart which acts as a pump and an intricate system of distributing pipes the blood vessels artery veins and capillaries. The heart and the blood vessels together form the cardiovascular system.
Blood is a fluid tissue. In human beings there is about 90 Ml of blood per kilogram of body weight. However this volume depends on the age and health of the individual. Blood has a specific gravity of 1.05 to 1.06 and pH of 7.4 . It is made up of fluid matrix called plasma abs and several types of cells termed formed elements or blood corpusles. These two components separate when blood is centrifuged. The plasma forms 54 % of the blood volume and the cells 45 % . The latter is referred to as the hematocrit or packed cell volume. The plasma contains many inorganic and organic substances. The formed elements consist of red blood cells or erythrocytes white blood cells or leukocytes and platelets or thrombocytes.
PLASMA ....
Blood plasma is the straw colored fluid obtained when all formed elements are removed from blood either by centrifugation or sedimentation. The ratio of plasma to formed elements is held relatively constant by the homeostasis controls of the body chemical. The composition of plasma is given...
The plasma contains inorganic salts with a dominance of chloride sodium and calcium ions and lesser quantities of potassium and magnesium ions. Smaller concentrations of bicarbonate sulfate and phosphate and traces of iron copper and iodine are aslo present.
The plasma also contains glucose which is used as a principal energy source in cellular metabolism. A variety of other substances such as amino acids vitamins lipids ( neutral fats and cholesterol) .hormones urea uric acid and other metabolite waste products are also present in the plasma . In addition it contains dissolved oxygen carbon dioxide and nitrogen. Plasma also reflects certain abnormal conditions occurring in cells and tissues of the body . For example within few houhours following a heart attack there is a noticeable increase in the level of the enzymes transamines and lactic dehydrogenase in the plasma membrane arising from the affected heart muscles. This has proved to be of significant value to a clinician in the diagnosis of heart attack.
The plasma membrane of man contains about 70 g proteins. Some of these proteins enzmic activities while other fractions show no activity at all. Plasma proteins are classified according to their molecular weight and electrical properties. Lipoproteins carry lipids and also transport lipid soluble vitamins and steroid hormones