Chapter 7 Textbook Notes

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University of Toronto Scarborough
Health Studies
Ingrid L.Stefanovic

HEALTH AND AGING TEXTBOOK NOTES Chapter 7: Aging and the Regulatory Systems In order for the organs to function properly, they must recognize changes in both the external and internal environment and be able to communicate with each other to maintain homeostasis, avert dangers, and manage growth. The regulatory systems that manage this communication are the sensory, nervous, endocrine, and immune systems. Sensory System The sensory system is composed of five senses: touch, smell, taste, hearing, and vision. Sensory organs allow the nervous system to gain information about the external environment. Age-Related Changes Touch The skin is the sense organ for touch. There are age-related changes in both touch receptors and pressure receptors. With age, these receptors decrease both in number and in sensitivity, resulting in degradation of the send of touch, with decreased ability to detect, locate or identify objects. Impaired ability to manipulate small objects is also developed. Smell Modest changes in the sense of smell occur with age, averaging at about only a 10% decline. There are decreases in both the number of sensory neurons in the nasal lining and in the olfactory pathways to the brain. Large individual differences occur in the preservation of the sense of smell however. Smoking degrades it, although some function may return if an individual quits smoking. The olfactory bulb is very close to the hippocampus, and one of the first indicators or incipient O]K0L2078L80,80L8,L80,80L39K08038041820OO There may be neurological changes in the olfactory bulb as well. 0J7,,9L438L39K0,-LOL994820OO1442,L25,L7,34O075078438,5509L90 The ability to smell is also important in detecting when food has gone bad. Taste Most of what we consider taste is actually a function of smell. %K09,890-:8L39K0943J:0.,3803808,O98Z00984:7-L99071,9,3:2,2LZKL.KL8.42548041 glutamate, best known in the form of monosodium glutamate (MSG) often used in Chinese cuisine. There are differing opinions on whether the sense of taste diminishes with age. At worst, aging may cause slight decreases in the sensitivity of these neurons, which may be below the sensory threshold and thus undetectable. Any gradual losses in taste may actually be due to smoking, periodontal disease, illness, or use of medications, whereas a sudden loss may be indicative of a brain tumor. Hearing Age-related changes in the auditory structures affect not only hearing but balance as well. Sound is transmitted through the outer ear via the ear canal into the middle ear through vibrations in the eardrum. The middle ear contains three ossicles, or little bones, that pass vibrations to the oval window, a flexible membrane that is the beginning of the inner ear. A highly complex structure in the inner ear, called the vestibule, allows organisms to sense gravity and head rotation. Many age-related changes can affect hearing and balance. Cells in the ear canal generate earwax, a lubricant that thickens with age and can build up, decreasing sensitivity to sound. Although the eardrum itself can become stiffer and the ossicles a bit arthritic, this does not tend to affect hearing. 1
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