Vascular blood system

The purpose of the blood vascular system is to provide rapid mass flow of materials from one part of the body to another.

The circulatory system consist of two circular systems of tubes, circulation through the lungs (pulmonary circulation) and circulation through the rest of the body.

Every blood system of circulation requires three characteristics:
*A pump – contractile
*A system of channels or tubes – blood vessels
*A fluid medium – blood

The blood flow in the closed vascular system is maintain by the pumping action of the heart. Blood is moved though these systems by two pumps, the right and left sides of the heart. It is enclosed in a tough membranous sac called the pericardium.

Although these right and left pumps beat together, the blood in each side is entirely separate, and the two pumps can and do to some extent, function independently. In one day the heart moves more than 700 liters of blood through the body. This is done by means of the rhythmic pumping action of the heart.

Because pushing blood through the lungs is much easier than pushing it though every part of the body, the left side of the heart is bigger, more muscular and carries a much heavier workload that the right.

Oxygen enriched blood from the lungs returns through the pulmonary veins to the left atrium. From the left atrium it enters the left ventricles, which pumps the blood through the aorta into the system circulation.
Vascular blood system

Hypertension and Calcium linked

Hypertension and Calcium linked
The high incidence of osteoporosis among the elderly, particularly women, has implicated a need for generous calcium intakes throughout life. Now another disease, hypertension, which affects as many as 58 million Americans and is particularly prevalent among the elderly, is being linked by some researchers to an inadequate intake of calcium.

Hypertension is an increase in vascular resistance most often due to a decreased luminal diameter of the arteries or arterioles. This decrease in luminal diameters is caused by excessive shortening of the vascular smooth muscle actomyosin; the initiator for the contraction (or shortening) is intracellular calcium. At first glance it seems quite incongruous that a deficiency of dietary calcium could be a cause of hypertension.

Many researches attempt to link hypertension to dietary factors and to treat the disorder by dietary manipulations. Dietary factors which have been investigated in relation to hypertension include, in addition to sodium and protein, total calories, fats, alcohol, chloride, potassium, magnesium, and calcium. Intensive research concerning the role of sodium in the development or treatment of hypertension has been particularly fruitful because through establishing the fact that certain populations of hypertensives (approximately 30% to 50%) are much more sensitive to an excess of sodium than others, it has strongly suggested that hypertension is a heterogeneous disease, having a variety precipitating factors.
Hypertension and Calcium linked