Which of the following vascular system changes results from aging?
A. Increased peripheral resistance of the blood vessels
B. Decreased blood flow
C. Increased workload of the left ventricle
D. All of the above
Correct Answer: D. All of the above
Aging decreases the elasticity of the blood vessels, which leads to increased peripheral resistance and decreased blood flow. These changes, in turn, increase the workload of the left ventricle. Some changes in the heart and blood vessels normally occur with age. However, many other changes that are common with aging are due to modifiable factors. If not treated, these can lead to heart disease.
Option A: Receptors called baroreceptors monitor the blood pressure and make changes to help maintain a fairly constant blood pressure when a person changes positions or is doing other activities. The baroreceptors become less sensitive with aging. This may explain why many older people have orthostatic hypotension, a condition in which the blood pressure falls when a person goes from lying or sitting to standing. This causes dizziness because there is less blood flow to the brain.
Option B: The main artery from the heart (aorta) becomes thicker, stiffer, and less flexible. This is probably related to changes in the connective tissue of the blood vessel wall. This makes the blood pressure higher and makes the heart work harder, which may lead to thickening of the heart muscle (hypertrophy). The other arteries also thicken and stiffen. In general, most older people have a moderate increase in blood pressure.
Option C: The heart has a natural pacemaker system that controls the heartbeat. Some of the pathways of this system may develop fibrous tissue and fat deposits. The natural pacemaker (the SA node) loses some of its cells. These changes may result in a slightly slower heart rate. A slight increase in the size of the heart, especially the left ventricle occurs in some people. The heart wall thickens, so the amount of blood that the chamber can hold may actually decrease despite the increased overall heart size. The heart may fill more slowly.