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The Special Senses. Ch. 17. Part 1 Objectives. Describe the olfactory receptors. Part 1 – Olfaction: Sense of Smell. Anatomy 3 types of cells Olfactory receptors – detect the smell and initiate the signal to the brain - PowerPoint PPT Presentation
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PART 1 – OLFACTION: SENSE OF SMELL Anatomy
3 types of cells Olfactory receptors – detect the smell and
initiate the signal to the brain Supporting cells – provide physical support,
nourishment, and insulation for receptors Basal cells – make supporting cells
Bowman’s glands Secrete mucus that moistens olfactory area
(boogers)
HYPOSMIA Reduced ability to smell Affects half of people over age 65 and
75% of people over age 80
Women smell better than men, especially during ovulation
Smoking can impair the sense of smell
PART 2 – GUSTATION: SENSE OF TASTE Only 5 primary tastes
Sour, sweet, bitter, salty, umami (meaty or savory)
all flavors are combinations of these tastes
Olfactory and gustatory senses are closely linked – like when you have a cold and food doesn’t taste the same It is your smell that actually isn’t working
properly
GUSTATION ANATOMY – P. 470 Taste bud – oval body consisting of cells Papillae – covered in taste buds
Vallate papillae – 12 very large, circular areas
Fungiform papillae – mushroom-shaped elevations scattered over area of tongue
Foliate papillae – small trenches on tongue – most taste buds are gone by childhood
Filiform papillae – no taste buds – just add friction to tongue making chewing and moving food easier
PART 3 OBJECTIVES List and describe the accessory
structures of the eye and the structural components of the eyeball.
Discuss image formation by describing refraction and accommodation.
Describe vision abnormalities.
ACCESSORY STRUCTURES OF EYE Eyelids – palpebrae
Functions: Shade eyes during sleep Protect eyes from light Protect eyes from foreign objects Spread lubrication over eyeballs
upper eyelid is more moveable – levator palpebrae superioris muscle
Where eyelids meet is called commissure – lateral and medial
Lacrimal caruncle – reddish bump in medial commissure that secretes oil and sweat – causes “sleep” in your eyes
INFECTIONS Sty – infection in oil gland of eyelash
follicle Chalazion – infection in tarsal glands of
eyelidTarsal glands secrete fluid onto eye for
lubrication
ACCESSORY STRUCTURES OF EYE Lacrimal apparatus
Produces and drains lacrimal fluid or tears
Eye muscles
TUNIC LAYERS Outer layer – fibrous
Cornea – transparent, focuses light raysSclera – white of the eyeOptic nerve – transmits info to brain
Middle layer – vascularChoroid coat – contains blood vesselsCiliary body – holds the lens in placeLens – focusingAqueous humor – fluid surrounding lensPupil – opening for light to enter
TUNIC LAYERS Inner layer
Retina – visual receptor cells
Vitreous humor – fluid supports internal structures
RETINA Made of cells that are light receptors –
photoreceptors Rods and cones
Rods – black and whiteCones - color
Color blindnessLack of cones
COLORBLINDNESSA genetic trait that affects boys more than girls. The location of the gene is on the X chromosome
IMAGE FORMATION Seeing is like taking a picture The object must be focused on a “film” –
retina The correct amount of light must be
present – pupil
Light bends - refraction
REFRACTION When light bends as it moves
between two mediums – air and water
Images on the retina are upside-down and have right-to-left reversal
IMAGE FORMATION PROCESS Light hits the cornea and is bent Light leaves the cornea and is bent
again Light enters the lens where it is focused
on the retina So why don’t we see everything upside-
down?Very early on the brain “learns” how to
coordinate the images and make them correct
ACCOMMODATION Most of the focusing is
done by the cornea 25% must be done by the
lens Our lens is convex on both
sides in order to produce clear images
The lens will increase its curvature in order to focus all images exactly
ANIMATIONS http://www.bbc.co.uk/science/humanbod
y/body/factfiles/sight/sight_animation.shtml
http://www.biologymad.com/resources/eye.swf
ABNORMALITIES AND CHANGES Presbyopia – lens loses elasticity with age
Around age 40 the lens can’t focus near images and people need glasses
Normal eye – emmetropic – can reflect images perfectly of objects 20 ft away
Myopia - near-sightedness Eyeball is too long for the focusing power of
the lens or lens is thicker than normal Hyperopia – far-sightedness
Eyeball is too short for the focusing power of the lens or lens is thinner than normal
PART 4 OBJECTIVES Describe the anatomy of the structures
in the three main regions of the ear. List the major events in the physiology
of hearing.
PART 4 – HEARING Anatomy of the ear
External ear Collects sound waves and
channels them inwardMiddle ear
Conveys sound vibrations to the oval window
Inner ear Houses the receptors for hearing
and equilibrium
OUTER EAR Auricle (pinna) – flap of elastic cartilage
shaped like a trumpet External auditory canal – curved tube that
lies in the temporal bone and leads from the auricle to the eardrum
Eardrum (tympanic membrane) – thin, semitransparent partition between the external auditory canal and the middle ear
Ceruminous glands – produce wax to protect ear from dust and foreign objects
MIDDLE EAR Small, air-filled cavity Contains 3 smallest bones in the body
Auditory ossicles Malleus, incus, and stapes
contains auditory tube (eustachian tube) – connects middle ear to the throat and nasal cavitiesHelps maintain air pressureCan lead to ear pain during sore throats
INNER EAR Labyrinth – communicating chambers
and tubes Contains
Semicircular canals – sense of equilibriumCochlea – sense of hearingOrgan of Corti – contains hearing receptors,
hair cells detect vibrations
HEARING Pinna directs sound waves into auditory
canal Sound waves strike ear drum and it
vibrates Auditory ossicles amplify vibrations to
cochlea Organs of Corti contain receptor cells
(hair cells) that deform the vibrations Impulses sent to nerves Temporal lobe interprets sensory
impulses
PART 5 - EQUILIBRIUM Balance – 2 types
Static – maintenance of body relative to gravity
Dynamic – maintenance of body in response to sudden movements like rotation, acceleration, and deceleration
Organs that control this are called the vestibular apparatus – all lined with hairsSaccule and utricleSemicircular ducts (canals)