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Chapter 7

HLTC22H3 Chapter Notes - Chapter 7: Etiology

Health Studies
Course Code
Ingrid L.Stefanovic

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Health, Illness, and Optimal Aging- Biological and Psychological Perspectives
Chapter 7: Aging of 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.
-Disruption in the communication among these systems plays a major role in the
development of disease and in the aging process itself.
-Less is known about how to maintain optimal health in these systems.
-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
-In the interest of brevity, we focus primarily on changes in the senses due to aging and
disease rather than describing the anatomy and physiology of these highly complex
organs in depth.
-Sense organ for touch
-Changes to touch receptors (Meissners corpuscles) and pressure receptors (Pacinian
-With age- these receptors decrease with number and sensitivity, degradation of the sense
touch, decreased ability to detect, locate, or identify objects
-Loss of sense of smell decreases by 10%
-Decreases in numbers of sensory neurons in the nasal lining, and in the olfactory
pathways to the brain
-Food-borne illnesses are a risk for older adults who have lost their sense of smell, and
they cant smell rotten eggs, milk or meat, as well as detecting leaking gases or bad body
-Test buds on the tongue can sense salt, sweet, sour, bitter, fat, and umami [glutamate
form of monosodium glutamate]

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Health, Illness, and Optimal Aging- Biological and Psychological Perspectives
-Gradual loss in taste, maybe due to smoking, periodontal diseases, or medication
-Serious consequences leads to anorexia
-Middle ear contains three ossicles (little bones) that pass vibrations to the oval window
-Fluid in inner ear puts pressure on the cochlea
-Vestibule, allows organisms to sense gravity and head rotation
oContains two small, geletin-filled sacks, with small mineral particles and hairlike
oThese minerals press down on the sensors, transmitting info to the brain on
position of the head-whether upright, down or tilted
Cells in the ear canal develop earwax, decreasing sensitivity to sound
Drugs, antibiotics, pain relievers, diuretics, and cancer drugs are toxic to
the ear and its Corti
Structure of the inner ear senses gravity & head position can also degrade
with time, leading to dizziness, and falls
Presbycusis - loss of hearing, most common hearing problem [men-90%
and women -30% by 90]
Hearing leads to older people becoming less attached to their environment,
not being able to participate in conversations, hear others, listen to music
or enjoy listening to nature
Tinnitus, ringing in the ears with no discernible cause [ear infections,
high blood pressure, diabetes, tumors, atherosclerosis, malnutrition,
medications, and toxin chemicals
-Cornea - through which light passes [transparent structure that protects the eye]
-Iris [contracts & dilates]- regulates the amount of light enters the eyes
-Retina - contains photoreceptors [rods & cones]lens focuses on the image on the retina
adjusting for the distance of the object
-Cones - colour vision
-Rods - black and white
-Humor - gel-like substance protects the eye against shock

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Health, Illness, and Optimal Aging- Biological and Psychological Perspectives
-The liquidy (water) humor provides support and transports nutrients and wastes
-Presbyopia- lens lose elasticity with age [difficult to focus on near objects]
-Cornea becomes irregular- resulting in astigmatisms, distorts vision b doubling the edges
of objects
-Muscles in iris decrease in number & strength, collagen stiffens [reducing pupil ability to
-Vitreous humor decreases in size, creates tension in retina, causing flashestoo much
tension causes retina to detach- leading to blindness
-Rods are more vulnerable to aging [become irregular, decrease ability to see dim light]
Age-Related Changes
-Dry eyes
-Cornea less sensitive
-Pupil may react more slowly
-Les able to tolerate glare
-Trouble adapting to light
-Eye muscles become less able to fully rotate the eyr
-Lens loses elastically with age, making it more difficult to focus on near objects
presbyopia (most common aging problem)
oA cataract is a clouding of the normally clear lens of your eye
oVery hard to read, and the face appears to be foggy
oEyes look cloudy surgery removes the cloudy part
Four Common Diseases
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