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Lecture

Chapter 7 Textbook notes


Department
Health Studies
Course Code
HLTC22H3
Professor
Anna Walsh

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Chapter 7- Aging and The Regulatory System
SENSORY SYSTEM
5 senses
Allows nervous system to gain information about the extrernal environment
Age Related Changes
Touch
Skin is a sense organ
Age related changes in: touch receptors (Meissner’s corpuscles) and pressure
receptors (Pacinian corpuscles)
Both decrease with age and in number and sensitivity
Decreased ability to locate, identify and manipulate objects
Smell
Only about 10% decline
Sensory neurons decrease in nasal lining and olfactory pathways
Smoking causes most severe degradation
May cause decrease in appetite, increases risk of food borne illnesses
Taste
Aging may cause minor decrease in sensitivity neurons
Loss in taste occurs because of smoking, periodontal disease, illness and medications
May lead to anorexia and increases mortality
Hearings
Changes affect both hearing and balance
Sound goes from outer ear ear canal middle ear through vibrations in the
eardrum
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Middle ear: 3 ossicles/little bones that pass vibrations to oval window
(hammer, anvil, and stirrup)
Oval window: flexible membrane at beginning of inner ear
Inner ear puts pressure on cochlea snail shell organ
Inner e3ar is lined with the basilar membrane which has rows of neurons
(thousands)
Neurons make up the organ of Corti (hair cells contact nerve fibers and
transmit acoustic signals to CNS
Vestibule
Complex structure in inner ear
Allows organisms to sense gravity and head rotation
Has 2 small gelatine filled sacs that have mineral particles and sensors
Minerals press down on sensors and transmit information to brain
With age: ear wax build up decreases hearing sensitivity
Organ of Corti affected by wear and tear and otoxic medications
Vestibule degrades leading to dizziness and falls
Presbycusis
hearing loss with age
Men lose 80% by age 90, women lose only 30%
Unable to hear high pitch sounds because of damage to shorter hair cells
close to cochlea
African men have less hearing loss genetic factor
Tinnitus
Ringing in the ears without a cause
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May be due to ear infection high blood pressure, diabetes and tumours,
arthrosclerosis, medications and toxins
Vision
Light passes through cornea transparent, protects the eye
Muscles in the iris control amount of light that enters the eye
Retina back of the eye; has photoreceptors with rods and cones
Rods: transmit black and white information; found in peripheral regions of
retina
Cones: transmit colour; numerous in macula; centre of gaze
Whole eye structure is supported by humours (gel like substance) which also
transports nutrients and waste
Conjunctiva is a clear mucus membrane inside eyelids that also provides protection
with age, cornea, lens and vitreous humour diminish in transparency, making
the eye sensitive to glare
lens becomes yellow and decreases ability to differentiate between colours
also loses elasticity, making it difficult to focus on objects
makes driving problemtic
4main eye diseases:
1.Cataracts
Cloudiness and opacity of the lens
Interferes with vision and especially in bright sun or at night
Leading causes of blindness and treated with curgery
2.Glaucoma
Causes by increased buildup of aqueous humour in eye
Resultys in increased intraocular pressure and damage to retina and optic
nerve results in blindness
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