The arteries, veins and capillaries, all posses the property of contractility on injury. In small vessels with minute ruptures, local vasoconstriction together with the deposition of platelets from flowing blood on the vessel wound may successfully seal off the gaps without the help of blood coagulation. But, when a large vessel is ruptured, these two physical processes are unable to seal off the gap in the blood vessel without the help of coagulation of blood. Thus, the two important intravascular factors in effecting haemostasis are the platelets and the coagulation of blood.
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- HAEMORRHAGIC DISORDERS Those pathological conditions of the body which allow to escape from the blood vessels, spontaneously or as the result of trauma unable in itself to cause haemorrhage in a normal person, are known as haemorrhagic disorders. There must be some defect in either one or two or all the three normal mechanisms of haemostatis to allow such disorders to supervene. A study of the complex and integrated mechanism of haemostasis can be classified as :...
- Defects and Abnormalities in the Extra-Vascular Factors The elasticity and resistance of the tissues surrounding the blood vessels protect them and resist the escape of the blood from the site of injury and help in closing the gap in the vessel. Therefore, when this tissue support is lacking as in the substance of the brain, the loose areolar tissue round the orbit or that surrounding the vessels of the antecubital and inguinal regions, a little trauma causes a large extravasation of the...
- ANEMIAS DUE TO BLOOD LOSS ACUTE HAEMORRHAGE Severe anemia following acute blood loss may occur after post-traumatic haemorrhage, ruptured duodenal ulcer, ectopic pregnancy and in haemophilia. The blood volume is first replaced by plasma, and there is a lowering of haemoglobin, marked increase in the platelets and leucocytes. In acute blood loss the R.B.C. and HB estimations give misleading informations regarding blood loss until the dilution of the blood by the tissue fluids has restored the blood volume 12 to...
- Defects and Abnormalities in Blood Vessels The conditions which come under this group can be classified under four heads. I. Congenial. Hereditary haemorrhagic telangiectasis, hereditary haemorrhagic thrombasthenia, Glanzmann’s and von Willebrand’s disease II. Infective . Toxic : Haemorrhagic scarlet fever, measles. Enbolic : Meningococcal or typhoid septicaemia, Endocarditis III. Nutritional. Vitamin C deficiency. IV. Allergic. Henoch-Schonlein purpuras, focal infection, serum sickness In all these conditions the determining factor of the haemorrhagic disorders is weakness of the capillary walls. The resistance of...
- Anemias due to Deficiency Iron deficiency Anemias . The blood picture is of the hypochromic microcytic type. The red cells contain less hemoglobin, hence low M.C.H.C. The factors which cause iron deficiency are as follows :- (1) chronic loss of blood by external haemorrhage – eg. Bleeding ulcers, tumours, piles, epistaxis, repeated haemoptysis, hook- worm disease etc. (2) excessive need of iron during growth, pregnancy, or lactation. (3) Inadequate absorption of iron due to diarrhea, vomiting, achlorhydria, and resection...