Answer
Autonomic nervous system(ANS) control of involuntary
physiological processes become increasingly inadequate in the old. The following are examples of the deficits;
1. Glandular secretions are less copious
2. Gastrointestinal (GI) motility dereases
3. The tendency to develop orthostatic hypotension increases
Work Step by Step
Manifestations of loss of ANS potency in the aged include the following insufficiencies: decreased glandular secretions; decreased GI motility; slower sympathetic vascular motor responses to changes in position.
Because of these ANS inefficiencies, the elderly complain more frequently of the following dysfunctions;
1. Dry eyes. This is due to the decrease in the secretion of
tears.
2. More frequent bouts of constipation, secondary to
decrease in GI motility.
3. Frequent episodes of orthostatic hypotension.
When an elderly person stands-- from a seated or
recumbent position-- his/her blood pressure does not
rise fast enough to push an adequate amount of blood
up to the now physically elevated brain.
This is so because the pressure receptors in the carotid
arteries and aorta do respond fast enough to the fall in
blood pressure.
Ordinarily, when a healthy adult is seated the blood pressure is adequate to keep blood flowing to the head and supplying the brain with oxygen. Under normal circumstance, if the seated person stands, gravity tends to cause blood to flow towards the legs. The body (ANS) must raise the blood pressure and heart rate to oppose the influence of gravity if blood is to keep going to the head in adequate amounts to keep the brain supplied with the oxygen it needs. If the normal blood pressure cannot be maintained, but falls out of the homeostatic range, the condition is known as orthostatic hypotension . Symptoms and signs (SS) of this condition include weakness. lightheadedness, blurred vision, and fainting(syncope). Orthostatic hypertension in the aged is not due the common causes( dehydration, anemia, blood loss or side effects of medications). Rather it is due to the reduced sensitivity of the baroreceptors in the carotid arteries and the aorta. Because of this deficiency the fallen pressure alert is too late to halt the gravity-induced blood pressure decrease before hypotension develops.
The ANS will try to raise the pressure as soon as it is alerted. But it may be too late to forestall the onset of weakness, blurred vision, dizziness or worse.
