Chapter notes

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29 Jun 2011

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HLTB01H3S: Health, Aging and the Life Cycle
A&G: Ch 7-Aging and the Regulatory Systems.
In order for the organs to function properly, they must be able to 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.
Includes: sensory, nervous, endocrine and immune systems
Sensory 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 environment.
Touchskin is the sense organ
oTouch receptors (Meissner’s corpuscles) and pressure receptors
(Pacinian corpuscles)
oDecrease in number and sensitivity with age
Smell – decrease number of sensory neurons in nasal lining and olfactory
pathways to the brain
oLoss of smell may be indicative of Alzheimer’s (olfactoryhippocampus)
Taste – differing opinions whether taste declines with age
Hearing – age related changes in hearing and balance
oSound is transmitted through the outer ear via the ear canal into middle ear
through vibrations in the eardrum
oMiddle ear contains 3 ossicles that pass vibrations to the oval window
oFluid in inner ear puts pressure on the cochlea, lined with the basilar
membrane, which has many neurons (make up organ of Corti)
oVestibule allows organisms to sense gravity and head rotation
oOtotoxicity: means by which hearing loss is induced by taking medication
oPresbycusis: hearing loss with age, moss common hearing problem
oStrawbridge, Wallhagen, Shema and Kaplan (2000) found a dose-
response curve between hearing impairment and problems in other
domains; there was a linear increase in problems in physical health, mental
health and social functioning with each decrement in hearing ability
oTinnitus: defined as a ringing in the ears with no discernable cause
Vision – cones = colour; rods = black&white, but more sensitive to light
ocones mostly in center (macula) of retina whereas rods are in the periphery
owhole structure supported by gel-like substances called humors in the
chambers in the eye
ocornea, lens and vitreous humor (protect) decrease in transparency w/ age
oPresbyopia: lens loses elasticity; hard to focus on near objects (common)
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oFour most common serious diseases of the eye is late life:
Cataracts: cloudiness or opacity of the lens, leading cause of
blindness in developing countries
Treated by removing and replacing damaged lens
Macular Degeneration: 2 types:
wet (exudative) AMD: sudden
dry (atrophic) AMD: 90%, gradual onset
Glaucoma: leading cause of blindness in adults over 50 (in US)
Caused by increasing buildup of aqueous humor in the eye,
resulting in intraocular pressure and damage to retina and
optic nerve
Diabetic retinopathy
Nervous System
Basic Anatomy and Physiology
The nervous system is the primary regulator of the body. It monitors and
provides communication between all the systems and regulates homeostasis.
Age-Related Changes
speed of action potentials decreases with age
Orthostatic hypotension: decrease in BP when going from supine to standing
Blood brain barrier: become more porous with age
Disease-Related Processes
CVAs result from the same ischemic problems as do myocardial infarctions or
heart attacks, which is why they are also called brain attacks.
Transitory ischemic attacks (TIA) - small temporary ischemic blockages
Aneurisms is a weakening of blood vessel causing it to rupture
Cerebral edema (swelling) can place pressure on tissues and cause damage
The incidence of dementia also increases with age. Dementia may be observed in
illnesses such as Vascular dementia, Alzheimer's disease (most common), Pick’s
disease, Creuztfeldt-Jakob disease and brain tumors.
AD characterized by neuritic plaques (composed of beta-amyloid proteins and
dead neurons) and neurofibrillary tangles (consisting of tau proteins and
In AD, massive loss of neurons, esp. Cholinergic, ventricles become enlarged
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