Effects of Aging on the Vascular System

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Chapter: Anatomy and Physiology for Health Professionals: Vascular System

As an infant is born, and the first breath is taken, many dramatic changes occur.

Effects of Aging on the Vascular System

As an infant is born, and the first breath is taken, many dramatic changes occur. The lungs and pulmonary vessels expand. There is a sudden decline in resistance within the pulmonary circuit. Blood moves quickly into the pulmonary vessels. In just a few seconds, ris-ing oxygen levels stimulate the ­ductus arteriosus to constrict. This isolates the pulmonary and aor-tic trunks from each other. Pressure rises in the left atrium, and the valvular flap closes the foramenovale . The site of the foramen ovale will, in adult-hood, be marked by a shallow depression in the inter-atrial septum known as the fossa ovalis. Throughout life, the remnants of the ductus arteriosus will appear as a fibrous cord called the ligamentum arteriosum.

Problems will eventually develop if normal cardio-vascular changes do not occur at birth or shortly there-after. These problems are related to which ­connection remains open, and how large the opening is. Surgery may be required to close the ductus arteriosus, the foramen ovale, or both. Additional congenital­ heart defects occur due to abnormal cardiac development, or because of inappropriate connections between the heart and its major veins and arteries. Common con-genital heart defects include patent foramen ovale, pat-ent ductus arteriosus, tetralogy of Fallot, ventricular septal defect, atrioventricular septal defect, and trans-position of the great vessels.

In the blood vessels, aging causes atherosclerosis, which can lead to an aneurysm and resultant stroke, myocardial infarction, or hemorrhaging. The depo-sition of calcium salts can weaken the vessel walls to increase risk of stroke or myocardial infarction. Ath-erosclerotic plaques can also cause the formation of thrombi. Atherosclerosis usually begins to cause prob-lems in middle or old age.

Between ages 25 and 45, men begin to have higher rates of developing atherosclerosis because they lack the amounts of estrogen to protect the blood vessels, which women have. Estrogen reduces resistance to blood flow as well as the risk of developing atherosclerosis in several­ ways: enhanced production of nitric oxide, blocking of voltage-gated calcium ion channels, and inhibition of the release of endothelin, a protein that constricts blood vessels and raises blood pressure. Estrogen also causes the liver to produce enzymes that increase catab-olism of low-density lipoproteins and the production of high-density lipoproteins. However, estrogen produc-tion begins to decline starting at age 45, and women then have closer rates of developing atherosclerosis to men of the same age. By age 65, men and women have the same risk for developing cardiovascular disease.

Congenital vascular problems, unlike congeni-tal heart problems, are rare. However, aging causes venous valves to weaken and purple varicose veins toappear. Signs of reduced circulation include cramping of muscles and tingling in the digits. Blood pressure also changes with age. With normal, healthy adults under age 40, average blood pressure is 120/80 mm Hg. After this age, hypertension occurrence is much more common, along with heart attacks, renal failure, strokes, and vascular disease. Other factors that result in vascular disease over our lifetimes include high-­ protein and high-lipid diets, empty calorie snacks, high stress levels, lack of aerobic exercise, smoking, and high alcohol­ intake. Cardiovascular­ disease can be ­prevented by regular aerobic exercise, healthy diet, avoiding smoking, and using alcohol in moderation.

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