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

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

4. External Structures of the Eye
Tarsal glands
located in the eyelids
produce an oily secretion
Ciliary glands
modified sweat glands
located between the eyelashes
Conjunctiva
membrane that covers the exposed eyeball and lines the eyelid
secretes a lubricating mucus

5. External Structures of the Eye
Lacrimal glands
above the lateral end of each eye
release tears through excretory ducts
tears contain lysozyme, an enzyme that attacks bacteria
tears drain into the lacrimal canaliculi located in the medial corner of each eye, then to the nasolacrimal duct, then to the nasal cavity

6. External Structures of the Eye
tarsal glands
ciliary glands
conjunctiva
lacrimal glands

7. Extrinsic Muscles 6 extrinsic eye muscles named by shape and location
rectus – long muscle fibers
oblique – muscles are at an angle
location – inferior, superior, lateral, medial

8. Extrinsic Muscles

9. Internal Structures of the Eye
eyeball is a hollow chamber filled with aqueous and vitreous humor- fluids that help the eyeball maintain shape
3 tissue layers form the wall of the eyeball
sclera
choroid
retina

10. 3 Tissue Layers of the Eyeball
Sclera
- outer layer of the eye
consists of the white part of the eye and the cornea
cornea contains no blood supply

11. 3 Tissue Layers of the Eyeball
Choroid
middle layer of the eye
contains rich supply of blood vessels
includes the iris
colored part of eye
contains 2 sets of muscles which control the amount of light admitted to the eye
sphincter pupillae – contracts in the presence of bright light or when the eye focuses on an object up close – pupil grows smaller
Dilator pupillae – contracts in the presence of dim light –or when the eye focuses on a distant object – pupil grows larger
includes the pupil – opening through which light passes into the
the interior of the eye

12. 3 Tissue Layers of the Eyeball
Retina
innermost layer of the eye
contains 2 types of light-sensitive sensory neurons
rods – activated in dim light
cones – sensitive to bright light and provide color vision
bipolar neurons provide connections between the retina
and rods and cones

13. Internal Structures of the Eye

14. Blind Spot
area on the retina where the optic nerve joins the eye – optic disc
no rods and cones on the optic disc
we do not perceive this blind spot because the brain fills in this visual info from the other eye

15. Lens located behind the iris transparent, flexible structure
held in place by suspensory ligaments which attach to the ciliary body
ciliary body contracts to view objects within 20 ft which
changes the shape of the lens – after the age of 40, the
ability of the ciliary body to contract diminishes

16. Vision optic nerve optic chiasm optic tracts
receive impulses from the rods and cones and transmits
the impulses to the brain
optic chiasm
location in the brain where the optic nerves cross
optic tracts
nerve fibers exiting the optic chiasm
carry visual stimuli to the occipital lobe

17. Vision Disorders

18. Vision Disorders
vision disorders

19. Eye Diseases Conjunctivitis Cataracts Glaucoma macular degeneration
also known as pink eye
contagious inflammation of the conjunctiva
Cataracts
Clouding of the transparent lens of the eye causing
blurred vision, poor night vision, and halos around light
Glaucoma
- increased pressure within the eyeball
macular degeneration
progressive loss of central vision
peripheral vision remains unaffected

20. Eye Diseases diabetic retinopathy vitreous floaters
- caused by long-term diabetes
damage to the retina caused by swelling and leaking
of the vessels that supply blood to the retina
- leading cause of blindness in American adults
vitreous floaters
tiny chunks of the gel-like vitreous humor break off and
float in the aqueous humor
- irregular shaped specks drift within your field of vision

21. Review and Assessment
Fill in the blanks with: choroid, cornea, cones, or vitreous. 1. The pupil is part of the _______________ tissue layer. 2. The two humors are aqueous and _______________. 3. The retina contains the rods and _______________. 4. The clear part of the sclera is the _______________.

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

23. Anatomy of the Ear external ear auricle auditory canal
Irregularly-shaped outer portion of ear
auditory canal
short, tube-like structure connected to the auricle
walls are lined with skin that contain ceruminous glands that produce cerumen (earwax)
tympanic membrane
eardrum
soundwaves cause the eardrum to vibrate
Separates the outer ear from the middle ear

24. Anatomy of the Ear middle ear (tympanic cavity)
ossicles – smallest bones in the body
hammer, anvil, stirrup
transmit and amplify sound waves
tympanic membrane attaches to the hammer which attaches to the anvil which attaches to the stirrup which attaches to the oval membrane
Eustachian tube
connects the middle ear to the pharynx
equalizes pressure on either side of the tympanic membrane

25. Anatomy of the Ear

26. Anatomy of the Ear internal ear
semicircular canals
bony labyrinth
winding tunnels
filled with clear fluid called perilymph
membranous labyrinth
inside the bony labyrinth
filled with thicker fluid called endolymph
cochlea
cochlear nerve carries information about hearing
vestibule
vestibular nerve carries information about balance
vestibular and cochlear nerves join to form the vestibulocochlear
nerve

27. Inner Ear

28. Hearing Sound waves enter the ear,
transmitted through the auditory canal - cause the tympanic membrane to vibrate
the hammer, anvil, and stirrup transmit and amplify the vibrations to the membrane of the oval window causing the fluid in the inner ear (endolymph) to be set into motion
cochlear duct - the membranous labyrinth inside the cochlea
inside the cochlear duct is the organ of Corti which contains hair cells which are specialized hearing receptors
these hair cells are stimulated by the motion of the endolymph

29. Hearing
stimulation of cilia cells stimulates the cochlear branch of the vestibulocochlear nerve
the cochlear nerve sends the impulse to the auditory region of the brain in the temporal lobe

30. Balance/Equilibrium
hair cells in the semicircular canals are stimulated by movement of endolymph in the canals
vestibular nerve is stimulated and information on body orientation is sent to the cerebellum

31. Disorders and Infections of the Ear
Deafness
Tinnitus
ringing in the ears
hair cells in the organ of Corti are damaged
often caused by repeated exposure to loud noise
external otitis (swimmer’s ear)
bacterial or fungal infection of the auditory canal caused
by immersion in contaminated water

32. Disorders and Infections of the Ear
otitis media (middle ear infection)
caused by bacteria or virus
common in infants and toddlers because their Eustachian tubes are not fully developed
treated with antibiotics or in chronic cases, tubes are inserted in the tympanic membrane to relieve pressure
labyrinthitis (inner ear infection)
often affects the semicircular canals
can cause vertigo (dizzines), nausea, and vomiting

33. Review and Assessment
True or False? 1. External otitis is swimmer’s ear. 2. The ossicles are in the external ear. 3. Hair cells are responsible for equilibrium. 4. The cochlea is part of the inner ear. 5. Labyrinthitis is an inner ear infection.

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

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

36. Olfactory Sense olfactory region olfactory receptor cells
olfactory hairs
olfactory filaments
olfactory nerve
olfactory bulb

37. Olfactory Sense

38. Injuries and Disorders of the Nose
rhinitis
inflammation of nasal membrane
septum problems
deviated septum

39. Gustatory Sense taste buds papillae gustatory cells gustatory hairs
taste pores
tastants

40. Disorders of the Tongue
infection
severely bitten tongue during a traumatic accident
tongue piercing
injury
abnormal growth
hairy tongue
burning mouth syndrome

41. Review and Assessment
Match these words with 1–4 below: gustatory, gustatory hairs, olfactory hairs, rhinitis. 1. inflammation of the nasal membrane 2. sense of taste 3. part of taste bud 4. part of sense of smell