The blood pressure is the arterial pressure exerted by the blood on the arterial walls. The maximum pressure during ventricular systole is called systolic pressure; the minimum pressure during ventricular diastole is called diastolic pressure. The systolic pressure is generated by the force of contraction of the heart; the diastolic pressure is chiefly due to arteriolar tone (peripheral resistance). The heart has to pump the blood against the diastolic pressure which is a direct load on the heart. Normally, the blood pressure is roughly 120/80 mm Hg, the systolic pressure ranging from 110-130, and the diastolic pressure from 70-80. The difference between systolic and diastolic pressure is called pulse pressure.
Hemorrhage (bleeding) is the obvious result of rupture of the blood vessels. Venous hemorrhage causes oozing of blood while arterial hemorrhage causes spurting of blood
Vascular catastrophes are of three types:
All of them result in a loss of blood supply to the area of distribution of the vessel involved, unless it is compensated by collateral circulation.
In old age the arteries become stiff. This phenomenon it called arteriosclerosis. This causes a variable reduction in the blood supply to the tissues and a rise in systolic pressure.
Arteritis and Phlebitis:
Inflammation of an artery is known as arteritis, and inflammation of a vein as phlebitis.
Atheroma are patchy changes developed in the tunica intima of arteries due to accumulation of cholesterol and other lipid compounds. Arteries most commonly narrowed arc those in the heart, brain, small intestine, kidneys and lower limbs. The changes are called thrombi.
Aneurysm is the swelling or dilation of blood vessels where part of the wall of artery inflates like a balloon. The wall of the blood vessel at the site of aneurysm is weaker and thinner than the rest of the blood vessels. Due to its likelihood to burst it poses a serious risk to health.
Buerger’s disease (thromboangitis obliterans):
This is a very painful condition. There is inflammation of small peripheral arteries of the legs. The victim is a young person and a heavy smoker.
In this condition there is spasmodic attack of pallor of the fingers due to constriction of small arteries and arterioles in response to cold.
The veins of the lower limbs are affected. Due to lack of movement of legs there is thrombus formation with mild inflammation. This thrombus may get dislodged and flow in the blood and may block any other artery. This condition is called embolism.
When the vein wall is subjected to increased pressure over long time there is atrophy of muscle and elastic tissue with fibrous replacement. This leads to stretching of the vein with tortuosity and localized bulging. Venous congestion of the feet is relieved by putting feet on the stool that is higher than the trunk, helping in venous return and relief in tiredness. Varicose veins may occur at the lower end of esophagus or in the anal canal.