1. The Sensory Systems 7
Lesson 7.1: The Eye Lesson 7.2: The Ear Lesson 7.3: Smell and Taste

2. Chapter 7: The Sensory Systems
Lesson 7.1
The Eye

3. The Eye anatomy of the eye (1” in diameter) vision
External- eyebrows, eyelashes, etc
internal
vision
injuries, diseases, and disorders of the eye

4. External Structures of the lubrication of the Eye
tarsal glands- oil
ciliary glands-mod sweat glands in lashes
Conjunctiva-externa+mucous
lacrimal glands- excretory ducts.

5. Extrinsic Muscles

6. Internal Structures of the Eye
Humors- maintain shape
Aqueous- anterior
Vitreous- posterior
tissue layers – there are 3
Sclera- outer (white part)
Cornea- “window”, no blood supply

7. Internal Structures of the Eye
Choroid- middle, vascular, pigmented layer (to prevent reflection)
Pupil- opening
Iris- color, lens of a camera- 2 muscles (sphincter and dilator pupillae) anterior to lens->convex and held by suspensory ligaments to focus light. Attached to cilliary body (part of Choroid)
Retina- inner, posterior only layer, nerve endings that connect to optic nerve
Rods- dim light, Cones- bright light, color, Optic Disc- “blind spot” between O. nerve and eye- no rods or cones

8. Internal Structures of the Eye

9. Vision retina impulse optic nerve brain optic chiasma optic tracts
occipital lobe

10. Vision Disorders

11. Eye Diseases conjunctivitis Cataracts Glaucoma
also known as pink eye- redness, pain, swelling, mucous
Contagious bacterial infection
Cataracts
Clouding of lens, “halos” usually >70 years
Sped up with exposure to bright sunlight
Glaucoma
Increased pressure of the eye- aqueous humor
Loss of peripheral vision first, but can cause full blindness
treat with medication and/ or surgery

12. Eye Diseases macular degeneration diabetic retinopathy
Central vision only, dry (thinning of retina- no full loss of vision) or wet (vascular leakage of vessels of the eye- surgical intervention necessary)
diabetic retinopathy
Swelling and leakage of retinal vascular supply (red spots)
If caught early, can be repaired. If not, will cause blindness
vitreous floaters
Chunks of vitreous break off- usually harmless unless accompanies by lateral flashes of light (possible retinal detachment)

13. Chapter 7: The Sensory Systems
Lesson 7.2
The Ear

14. The Ear anatomy of the ear functions of the ear
Outer, middle and inner
functions of the ear
Hearing and Equilibrium
disorders and infections of the ear

15. Anatomy of the Ear- 1 of 3 External ear auricle (pinna) auditory canal
External acoustic meatus
1” long, ¼” diameter tube
Lined with ceruminous glands (earwax)
Cleans, lubricates and protect the ear
tympanic membrane
Eardrum separates outer and middle ear
Sound waves cause it to vibrate

16. Anatomy of the Ear (2 of 3) Middle ear (tympanic cavity)
Open chamber in the temporal lobe of the skull
T. membrane is on the lateral side
Medial side is membrane covered oval window ( superior) and round window ( inferior)
Ossicles (3 smallest bones in the body) connect the t. membrane and oval window: Transmit and amplify sound waves
Malleus (hammer) attaches to t membrane
incus (anvil) attaches to malleus
stapes (stirrup) attaches to incus and oval window
Eustachian tube connects middle ear to pharynx
Equalizes pressure (chewing gum or yawning in a plane)

17. Anatomy of the Ear 3 of 3 Internal ear- Balance semicircular canals
Bony labyrinth
Parilymph- clear
Membranous labyrinth contained within
Endolymph- thicker
Vestibule
Central portion
Transmits balance information
Cochlea
Shell
Nerve transmits information about hearing
Vestibular and cochlear nerves join to form the vestibulocochlear (the name of a cranial) nerve

18. Anatomy of the Ear

19. Functions of the Ear Hearing
Vibrations of the t. membrane move the ossicles, which move the oval window and the fluids of the inner ear
Cochlea allows hearing
cochlear duct is central, membranous labyrinth of cochlea
Spiral organ of Corti contains hair cells (hearing receptors)
Stimulated by endolymph moving tectorial membrane
Short hair cells =higher pitches
Longer hair cells =lower pitches (more flexible)
Hair cells stimulate cochlear nerve
Nerve sends signals to temporal lobe of brain

20. Functions of the Ear Equilibrium Balance Vestibule
Comes from the inner ear
Vestibule
semicircular canals (3)
Contain hair cells
Stimulated by endolymph movement
Vestibular hair cells stimulate the vestibular nerve and transmit to the cerebellum for both static (in one place) or dynamic ( moving) equilibrium

21. Disorders and Infections of the Ear
Deafness: any loss of hearing
Can be caused by injury to the inner or middle ear, loud noises regularly, damage to the hair cells, earwax, scarring of the t. membrane, damage to auditory nerves or brain.
Presbycusis- age related hearing loss
Hearing aids amplify all sounds or boost certain frequencies
In canal- inside ear canal (mild to moderate)
Half shell- in the outer pinna (mild to moderately severe)
Behind the ear- most types of loss

22. Disorders and Infections of the Ear
Tinnitus: ringing in the ear
Damaged hair cells= random movement
Loud music or noise exposure ( more common in recent years….. Headphones?)
external otitis (swimmer’s ear)
Bacterial or fungal infection of auditory canal
Pain, fever, temporary hearing loss
Prevention- clean and dry ear canal after submersion in water

23. Disorders and Infections of the Ear
otitis media (middle ear infection)
Bacterial or viral, usually URI
Common in babies and toddlers (lack of eustachian development)
Pain, swelling, pus
Antibiotics if bacterial
“ tubes” in t. membrane to equalize pressure
labyrinthitis (inner ear infection)
Swelling in semicircular canals (Antibiotics if bacterial)
Vertigo (severe dizziness), nausea and vomiting
Chronic inflammation=Meniere’s disease
Perioidic, severe vertigo and progressive hearing loss

24. Chapter 7: The Sensory Systems
Lesson 7.3
Smell and Taste

25. Smell and Taste olfactory sense (sense of smell)
injuries and disease of the nose
gustatory sense (sense of taste)
disorders of the tongue

26. Olfactory Sense olfactory region- dime sized on top of nasal cavity
olfactory receptor cells- neurons responsible for smell
olfactory hairs extend from ORC into nasal cavity
Covered with mucous
Odor molecules erode mucous and stimulate hairs
Very few molecules required to send impulse- smell acclimation
olfactory nerve
made of olfactory filaments.
Send impulses to olfactory bulb to olfactory cortex of brain
Passes through the limbic system
Smells tied to memory

27. Olfactory Sense

28. Injuries and Disorders of the Nose
rhinitis
inflammation of nasal mucous membranes
Common cold, allergies, drugs
Irritation releases histamines to produce drainage and congestion
Taking antihistamines blocks release of histamines and prevents action
septum problems (septum divides L and R nares)
deviated septum usually due to injury. Surgical repair
Perforated septum- holes in septum (drugs, injury, toxic fumes). Surgical repair

29. Gustatory Sense taste buds (>10,000)
All over the inner mouth
Most as Papillae: T.B. on tongue
gustatory cells on papilla send up gustatory hairs through taste pores (openings in taste buds)
Tastants : chemicals from dissolved food in saliva
Stimulate gustatory hairs to send impulses to brain
Through the facial nerve, glossopharyngeal and vagus nerve
5 basic tastes: sweet, salty, sour, bitter, umami
Umami- beef/ MSG
One g. cell= 1 taste, but each papilla contains cells, so all 5 are covered

30. Gustatory Sense 70-90% of taste is influenced by smell.
Smell allows us to distinguish tastes
Over 10, 000 flavors
Flavor is
Taste
Smell
Texture
Consistency
Temperature

31. Disorders of the Tongue
Infection/ Injury
severely bitten tongue during a traumatic accident
tongue piercing
Both require antibiotics
Fastest healing part of body. Why?
abnormal growth on tongue
hairy tongue (abnormal growth of gustatory hairs)
Poor hygiene, tobacco, medications, radiation
Good hygiene prevents AND cures
burning mouth syndrome
Many causes, including damage to receptors, dry mouth, nutritional deficiencies, infection, hormones
Treatment based on symptoms and causes