Cardiovascular system Changes Across the Life Span

later Adulthood

As adults move into later life, the efficiency of the heart drops to as much as 80%. There is also a decrease in elasticity of the muscles of the heart and blood vessels, which leads to decreased cardiac output. Exercise, not smoking, and a healthy diet significantly improve and protect the cardiovascular system. Cardiovascular disease is the leading cause of death and disability for both men and women. By age 70, cardiac output is 70% of what it was at age 30. The number and size of cardiac muscle cells decrease, leaving a reduced strength of the heart. The valves also become calcified making them inefficient. The SA node and AV node become replaced by fibrous connective tissue, causing a delay in the electrical conduction of the heart. In some cases, the SA node must be replaced with a pacemaker. Atherosclerosis increases, reducing the diameter of the inside of the blood vessel and limiting the amount of blood that can circulate through the body. In some cases, complete occlusion occurs. If these occur in cardiac arteries or arteries of the brain, myocardial infarction or stoke occur, respectively.

Children

As infants grow, the pulse rate decreases and blood pressure increases. The capillaries also increase in their ability to respond to hot and cold environmental changes, which helps in thermoregulation. Juvenile hypertension occurs when there is a sustained blood pressure of above 90 mm Hg diastolic pressure. During childhood, the heart grows slowly and the left ventricle tends to be a bit larger. Before the heart size catches up to the growing body, children may tire easily and struggle with sustained physical activity.

Adolescents

During adolescence, the heart continues to grow; however, it will not "catch up" with the rest of the body until about age 17 or 18. Hypertension is increasing in adolescents. Experts believe the increase to be the result of poor diets, higher obesity levels, and the increase in number of teens who smoke.It is thought that 10 to 30% of adolescents are obese and about 80% of those will remain obese as adults. Obesity is a leading risk factor in cardiovascular disease.

Adulthood

Maximum physical potential is reached during young adulthood. Heart and circulatory changes occur gradually with age, depending on exercise levels and diet. During early adulthood, cholesterol levels increase. Arteries become less elastic and there is an increased risk for vascular diseases such as hemorrhoids and varicose veins. Unhealthy lifestyle habits (lack of nutrition, exercise, stress, and so forth) can lead to cardiovascular disease.

Infants

The heart rate of a newborn is typically higher than that of an adult (about 100 to 160 beats per minute). The blood pressure, however, is typically lower (under 90/60 mm Hg). Vital signs are not very stable in a newborn, but become stabilized as the infant grows. Since the capillary beds are less developed, infants have a very limited ability to respond to hot and cold environments using thermoregulation.