Disorders Related to the Circulatory System
Any kind of abnormal condition, either in the circulatory system or in the heart, may affect the overall physiology of the circulation. Very often, it is expressed as one or the other kind of disease. A few of such diseases are as follows:-
It is a manifestation of increase in the blood pressure of a person. The normal arterial systolic and diastolic pressure of a healthy individual is 120 mm Hg and 80 mm Hg, respectively. Under various physiological conditions, moderate level of fluctuation may occur. But the increase in the blood pressure beyond 140 mm Hg (systolic) and 90 mm Hg (diastolic), is referred to as high blood pressure. Its degree may vary from mild to high. A continuous or sustained rise in the arterial blood pressure is known as hypertension. High blood pressure can potentially harm the three vital organs i.e. heart, brain and kidneys. High blood pressure compels the heart to work excessively, due to which the congestive heart disease may set in at an early age. In brain, it can cause hemorrhage, or infarctions, leading to various disabilities. In the long-run, it also affects the kidneys, leading to renal failure.
It refers to the deposition of lipids (specially cholesterol) on the wall lining the lumen of large and medium sized arteries. Such a deposition is called atheromatous or atherosclerotic plaque. Its formation starts with the deposition of minute cholesterol particles / crystals in the tunica intima and smooth muscles. Gradually, these plaques grow due to the proliferation of the fibres and small muscles around it. This results into the reduction of the lumen size of the artery, and consequently the flow of blood is also reduced. In extreme circumstances, these plaques may completely block the artery. The proliferation of smooth muscles occurs because these plaques provide a rough surface to the platelets causing the release of platelet derived growth factor (PDGF). Such plaques, if formed in the coronary artery, reduce the blood supply to the heart, or may stop the supply due to complete blockage. This may result in heart attack or stroke.
It refers to the hardening of the arteries due to deposition and thickening. In the case of arteriosclerosis, calcium salts precipitate with the cholesterol of the forming or formed plaque. This calcification of the plaques, ultimately makes the wall of the arteries stiff and rigid, and is referred to as the 'hardening of the arteries'. Such an affected artery loses the property of distension, and its walls may rupture. The blood leaking from the ruptured wall may clot and block the pathway of blood flow. Such a thrombosis or clot formation in the coronary artery, may lead to a heart attack and even death.