Blood vessels
- Receptors, called baroreceptors, monitor the blood pressure and make changes to help maintain a fairly constant blood pressure when a person changes positions or 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. - The capillary walls thicken slightly. This may cause a slightly slower rate of exchange of nutrients and wastes.
- 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 hypertrophy (thickening of the heart muscle). The other arteries also thicken and stiffen. In general, most elderly people experience a moderate increase in blood pressure.
Blood
- The blood itself changes slightly with age. Normal aging causes a reduction in total body water. As part of this, there is less fluid in the bloodstream, so blood volume decreases.
- The number of red blood cells (and correspondingly, the
hemoglobin andhematocrit levels) are reduced. This contributes to fatigue. Most of the white blood cells stay at the same levels, although certain white blood cells important toimmunity (lymphocytes) decrease in number and ability to fight off bacteria. This reduces the ability to resist infection.
EFFECT OF CHANGES
Under normal circumstances, the heart continues to adequately supply all parts of the body. However, an aging heart may be slightly less able to tolerate increased workloads, because changes reduce this extra pumping ability (reserve heart function).
Some of the things that can increase heart workload include illness, infections, emotional stress, injuries, extreme physical exertion, and certain medications.
COMMON PROBLEMS
