Preksha Dhyana Human Body Part 2

Author(s): Jethalal S Zaveri
Publisher: Jain Vishva Bharati

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Haemorrhage is the escape of blood from the blood vessels. Uncontrolled bleeding is a serious threat to life. As a first-aid measure, excessive bleeding is most effectively controlled by direct pressure at the site of the injury. Gauze applied over the bleeding surface can help by promoting the breakdown of platelets, initiating the reactions of clotting. The body has an assortment of mechanisms for compensating a moderate loss of blood (e.g. loss by donation). The capacity of the system is decreased by vaso-constriction. The liver and spleen contract and sent their blood reserves into the veins. Tissue fluids diffuse into the vessels. Thus plasma volume is regained in a few hours; plasma proteins are restored more slowly and formed elements (viz. red blood-cells, white bloodcells, platelets) may take a month or more. In more severe haemorrhage, symptoms of shock may develop : the pulse rapid and weak, the skin pale, clammy and cold. If more than 30 to 35 percent of the total blood volume is lost, the body cannot compensate rapidly enough. Unless a blood transfusion is administered quickly, the victim may die.
Fatal heart-attacks are caused by a blood clot lodging in the coronaries of the heart, blocking flow of blood and causing irreparable damage to the heart muscle. Normally blood clotting oceurs when a blood vessel is damaged, to stop the loss of blood. Sometimes, however, clots form inside an undamaged blood vessel. The clot is called thrombus and partial or complete blocking of a blood vessel is called thrombosis. A travelling thrombus is called an embolus. Ultimately, if the embolus reaches a vessel that is too narrow, it may plug the vessel. The amount of damage caused by an embolus depends on the region in which it lodges. A coronary embolus can cut off the supply of oxygen to the heart and cause a heart-attack. An embolus carried to the blood vessels of the brain may result in a stroke causing a loss of part of the mental function or death.
What causes clot-formation inside a blood vessel? The introduction of any foreign substance into the blood streameven a large air bubble introduced during the improper administration of an injection-might provide a nucleus for
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