THROMBOSIS Definition and Effects Thrombosis is the process of formation of solid mass in circulation from the constituents of flowing blood; the mass itself is called a thrombus. In contrast, a blood clot is the mass of coagulated blood formed in vitro e.g. in a test tube Haematoma is the extravascular accumulation of blood clot e.g. into the tissues. Haemostatic plugs are the blood clots formed in healthy individuals at the site of bleeding e.g. in injury to the blood vessel. In other words, haemostatic plug at the cut end of a blood vessel may be considered the simplest form of thrombosis. Haemostatic plugs are useful as they stop the escape of blood and plasma, whereas thrombi developing in the unruptured cardiovascular system may be life-threatening by causing one of the following harmful effects: 1. Ischaemic injury . Thrombi may decrease or stop the blood suppl...
NOMENCLATURE AND CLASSIFICATION INTRODUCTION . The term ‘neoplasia’ means new growth;the new growth produced is called ‘neoplasm’ or ‘tumour’.However, all ‘new growths’ are not neoplasms since examples of new growth of tissues and cells also exist in the processes of embryogenesis, regeneration and repair,hyperplasia and hormonal stimulation. The proliferation and maturation of cells in normal adults is controlled as a result of which some cells proliferate throughout life (labile cells),some have limited proliferation (stable cells), while others do not replicate (permanent cells). On the other hand, neoplastic cells lose control and regulation of replication and form an abnormal mass of tissue. Therefore, satisfactory definition of a neoplasm or tumour is ‘a mass of tissue formed as a result of abnormal, excessive, uncoordinated, autonomous and purposeless proliferation of cells even after cessation of stimulus for growth which caused it’. The branch of science dealing wi...
EMBOLISM Definition and Types Embolism is the process of partial or complete obstruction of some part of the cardiovascular system by any mass carried in the circulation; the transported intravascular mass detached from its site of origin is called an embolus. Most usual forms of emboli (90%) are thromboemboli i.e. originating from thrombi or their parts detached from the vessel wall. Emboli may be of various types: A. Depending upon the matter in the emboli: i) Solid e.g. detached thrombi (thromboemboli), athero-matous material, tumour cell clumps, tissue fragments, parasites, bacterial clumps, foreign bodies. ii) Liquid e.g. fat globules, amniotic fluid, bone marrow. iii) Gaseous e.g. air, other gases. B. Depending upon whether infected or not: i) Bland, when sterile. ii) Septic, when infected. C. Depending upon the source of the emboli: i) Cardiac emboli from left side of the heart e.g. emboli originating from atrium and atrial ...