Effect of Aging on the Cardiovascular System
With aging, there is a general increase in collagen fibers in the heart. The size of the heart decreases with age, with some increase in the size of the left ventricle. The exact cause of these changes is difficult to determine because a large number of elderly per-sons have associated heart disease. The valves begin to thicken as a result of degeneration of collagen fibers and accumulation of lipids and calcium. The contraction force of the heart is decreased, reducing cardiac output and blood flow to organs. With age, blood flow to organs such as the brain and kidney are reduced as a result of changes in cardiac output and in blood vessels supplying the organs. There is a de-cline in maximum heart rate.
The aorta thickens and becomes less elastic. There is an increase in connective tissue, with a reduction in elastic tissue in large arteries. This results in needing greater pressure to push the blood into the stiffened arteries, with a resultant rise in systolic blood pres-sure. The smooth muscles of the blood vessels re-spond less well to the sympathetic nerves and cardio-vascular responses to exercise and stress, etc., are blunted. The baroreceptors are also less sensitive with age, which is one reason why elderly persons feel dizzy when they suddenly change posture (orthostatic hypotension). The basement membrane around the capillaries thickens, slowing down the exchange rate of nutrients and waste products between cells and blood.
Part of the bone marrow is replaced with connective tissue and fat slowing down the production of blood cells. As a result, red blood cells are reduced in num-ber. There is a tendency for blood to clot as a result of increased platelet activity. Total blood cholesterol tends to increase together with an increase in low-density lipoproteins (LDL) and a decrease in high-density lipoproteins (HDL), making the person more susceptible to such conditions as atherosclerosis.
Many studies have shown that adequate physical ex-ercise can delay and reduce the cardiovascular changes that result from age.1 Studies also show that the incidence of heart disease is much less in physi-cally active individuals.1