Human Anatomy & Physiology (9th Edition)

Published by Pearson
ISBN 10: 0321743261
ISBN 13: 978-0-32174-326-8

Chapter 15 - The Special Senses - Review Questions - Page 589: 38


Efficiency and sensitivity of all the organs of special sense deteriorate slowly with aging. Most of these negative changes are noticeable by about the end of the sixth decade of life. Hearing: Primarily because of damage to the spiral organ, hearing is noticeably less sensitive by the age of 60 Taste: Taste begins to deteriorate by the fourth decade because of a gradual decrease in the number of taste receptors ( taste buds) Smell: Ability to detect odors also decreases with advancing age. By the age of 60 most people are aware of a diminution in the acuity to detect odors. Sight: The lens of the eye becomes increasingly more cloudy with advancing age: Pupils tend to remain partially constricted: the result is that a progressively smaller amount of light reaches the retina as one ages. By the middle 70's, for most people, visual acuity is appreciably lower.

Work Step by Step

Effects of Aging on the Special Senses . Hearing deteriorates : By age 60 there is a perceptible decrease in sensitivity of the spiral organ. High pitched sounds are especially difficult to hear if one's hair cells have been damaged by exposure to very loud noises over extended periods. In the elderly, hair cell replacement is slow and presbycusis develops. About 50% of people over 75 have some degree of presbycusis Sensitivity to tastants begins to deteriorate in the late 40's.This due is primarily to the physical decrease of the number of taste buds. However, odor detection is an important component of the ability to taste . A t some stage in the middle 60's the combination of the decrease of taste sensation and the lowered sensitivity to odorants results in the elderly not enjoying food as much as they did before. Food tastes "bland" because of the deficits in taste and smell : as a consequence appetite decreases. This can lead to a serious decrease in the intake of an adequate number of calories. In such a circumstances, pathologic weight loss and premature may ensue. Sight. Poorer vision accompanies advancing age. The diminution is due mainly to two pathologic developments: cataract formation and macular degeneration.. Cataracts are caused by development of cloudiness of the lens . This cloudiness blocks light transmission and also causes diffusion of light rays Deterioration of the macula affects the fovea and the acuity of central vision. As one gets older the pupil can become only partially constricted: this also impairs visual acuity. A number of serious eye disease such as glaucoma are more prevalent among the elderly. Cataracts are routinely treated by lens replacement and there are effective treatments for glaucoma.
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