Plasma factor defects. Deficiency of accelerators of prothrombin activity gives rise to haemophilia in which the coagulation time is prolonged. Haemophilia is inherited as a sex-linked recessive character transmitted from affected males to unaffected female conductors. Haemorrhage occurs either spontaneously or from slight trauma. Subcutaneous or intramuscular haemorrhage and bleeding from the mucous membrane of mouth are common. Haemorrhage into the joints is often (haemarthrosis ) characteristic. An absence of the Factor VIII (anti – haemophilic globulin) in the plasma of these patients is the cause of inhibition of prothrombin activation in the first stage of blood coagulation process.
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- DEFECTS IN COAGULATION FACTORS A study of the normal blood coagulation process reveals a two-stage reaction in which four main concepts about the chemistry of blood coagulation are integrated in proper order. The first stage of the reaction, in which the prothrombin of plasma is activated to thrombin represents a co-ordination of the first two concepts, viz., (1) prothrombin activation and (2) inhibition of prothrombin activation. The second stage of the reaction in which thrombin interacts with plasma fibrinogen...
- What is Prothrombin Prothrombin is a glycoprotein in the liver with the help of vitamin K and present in the blood plasma in the normal concentration 15 to 20mg. per 100ml. of plasma. Normally there in a large excess of prothrombin in plasma over the amount required for effecting coagulation of blood. Therefore, a reduction of prothrombin to a large extent is required before a prolongation of the coagulation time is noticed. Prothrombin has a molecular weight of...
- Prothrombin defect Prothrombin defects – congenitial (Haemorrhagic disease of the new-born) This is due to an exaggeration of the temporary physiological fall of prothrombin that occurs between the 1 st and 5th day of life, occurring in about 1% of new-born infants. At birth the baby has no reserve of vitamin K and its formation by bacterial synthesis in the baby’s intestine takes time until a bacterial flora has been established in it. Haematemesis, melaena and bleeding...
- DEFECTS IN PLATELETS Platelets are derived from megakaryocytes of bone marrow. These are oval and thin, non-nucleated discs 2 to 3 microns in diameter. Normal count – 250,000 – 500,000 per c.mm. of blood. Agglutination of platelets is favoured by substances exuded by injured tissue, and inhibited in vitro, by anticoagulants like citrate or oxalate, or in vivo, by heparin and dicoumarol. Their number is increased by the acute blood loss, trauma, partial asphyxia and splenectomy. The platelets...
- 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...
- Defects in the Intra-Vascular Factors 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....
- 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...
- Myeloids Leukemias ACUTE MYELOID LEUKEMIA Commonly in children and young adults; more males. The onset is often sudden ; high rise of temperature, pain in the back and limbs, a sore throat, and bleeding from the gums. Rapidly progressing anaemia, tenderness over the sternum and other bones. In the terminal stage , enlarged spleen and liver, a generalized haemorrhagic tendency ; death in a few months. Blood Changes Total WBC – 20,000-50,000 per c.mm, rarely above 100.000per...
- 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...
- 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...