1. Bell Activity Turn to Chapter 8: Special Senses Complete the worksheet
“I See What Doesn’t Belong”

2. Ambiguous Illusions This man looks like your average Joe right?
But what else is he?
Is this a rabbit or a duck?

3. Special Senses Objectives 3.7 Analyze (explain) sensory perceptions.
3.8 Analyze (explain) diseases as related to eachsystem
Seeing Hearing Smelling

4. Special Senses Special senses allow body to react to the environment
Body able to see, hear, taste, smell, and to maintain balance
Senses occur because the body has structures that receive sensation, nerves carry message to brain, and brain interprets and responds to message

5. The Eye and Vision Sense of sight
Light rays transmitted to the optic nerve
Optic nerve relays information to brain for interpretation
Eye is well protected by:
Bony socket
Eyelids and eyelashes
Lacrimal glands– tears empty into nasal cavity
Conjunctiva– thin membrane lines eyelids

6. Tunics of the Eyeball
Sclera
Choroid coat
Retina

7. Sclera 1. Outer layer 2. White of the eye
3. Tough coating, helps maintain shape of eye
4. Muscles responsible for moving eye attached to sclera = extrinsic muscles

8. Choroid coat
1. Middle layer of eye, contains blood vessels to nourish eyes
2. Opening in front is pupil
3. Colored, muscular layer surrounding pupil
is iris
4. Intrinsic muscles – change size of iris to control amount of light entering through pupil

9. Retina 1. Innermost layer 2. Light rays focus image on retina
3. Image travels to the cerebral cortex via optic nerve
4. Rods –special cells sensitive to dim light
5. Cones – special cells sensitive to bright
light and color
6. Optic disc – on retina, known as blind spot, nerve fibers that form optic nerve

10. Other Special Structures
Lens
1. Crystalline structure located behind iris and pupil
2. Elastic, disc-shaped, biconvex
3. Situated between the anterior and posterior chambers
Anterior Chamber- filled w/ Aqueous humor
Posterior Chamber- filled w/ Vitreous humor
Muscles

11. Internal Anatomy of Eye

12. Internal Anatomy of Eye

13. Diseases and Abnormal Conditions
Amblyopia – lazy eye
Astigmatism
Cataract
Conjuctivitis – pink eye
Glaucoma

14. Diseases and Abnormal Conditions (continued)
Hyperopia – farsightedness
Myopia – nearsightedness
Presbyopia
Strabismus

15. Ophthalmoscope. In addition to examining the cornea, lens, and
vitreous humor for
opacities (cloudiness),
the examiner can see
the blood vessels at the
back of the eye (fundus)
and note degenerative
changes in the retina.

16. The Ear: Hearing and Balance
Controls hearing and balance
Sound waves transmitted to the auditory nerve
Auditory nerve relays information to the brain for interpretation
Consists of the outer ear, middle ear, and inner ear

17. Outer Ear Pinna or auricle a. Visible ear b. Collects sound waves
External auditory canal- ear canal
Tympanic membrane-– ear drum, separates outer and middle ear

18. Middle Ear 1. Cavity in temporal bone
2. Connects with pharynx by Eustachian tube - which equalizes pressure in the middle ear with outside atmosphere
3. Bones - transmit sound waves from ear drum to inner ear
a. Malleus (hammer)
b. Incus (anvil)
c. Stapes (stirrup)

19. Inner Ear
1. Cochlea - spiral shaped organ of hearing, contains a membranous tube,the cochlear duct – which is filled with fluid that vibrates when soundwaves are transmitted by the stapes
2. Organ of Corti – delicate hairlike cells that pick up vibrations of fluid andtransmit them as a sensory impulse along the auditory nerve to the brain
3. Semicircular canals – three structures in inner ear that contain liquid setin motion by head and body movements
4. Impulses sent to cerebellum to help maintain body balance (equilibrium)

20. Internal Anatomy of Ear

21. Internal Anatomy of Ear

22. Diseases and Abnormal Conditions
Hearing loss
Meniere’s disease
Otitis externa
Otitis media
Otosclerosis

23. The Chemical Senses: Taste and Smell
Taste receptors located on the tongue
Four main tastes
Sweet
Salty
Sour
Bitter

24. Sense of Smell Nose is the organ of smell
Olfactory receptors in nasal cavity
Impulses carried from the olfactory nerve to the brain for interpretation
Humans can detect over 6,000 smells
Sense of taste and smell related