1. 8
24 slides
1 hour & 30 min
Special Senses

2. The Special Senses
Introduction
*Special senses are? Define each.

3. II. The EYE

4. A. Accessory Structures of the Eye
1. Eyelids
2. Eyelashes
3. Conjunctiviva
= Membrane
Anterior outer eye
surface and inside . of eyelids
Secretes mucus:
Conjunctiva
Posterior Surface
Eyelid

5. Conjunctivitis = Inflamation of Conjunctiva; Pink Eye caused by bacteria or virus and is very contagious

6. Accessory Structures of the Eye …
4. Lacrimal gland
Functions:

7. B. Layers of the Eye 1. The Fibrous Layer
a. Sclera: Location = White of Eye; 5/6 eyeball
Function: Protects, Shapes, and Anchors muscles
b. Cornea: Transparent Convex Bulge, anterior 1/6 eye
Function: lets light in and bends it a bit to help in focusing

8. 2. Vascular Layer
Choroid: Brown Membrane; back and sides of layer
Function: Blood vessels & absorbs stray light
b. Ciliary body: Thickened Ring of Tissue encircling the Lens made up of mostly smooth muscle
Lens
c. Iris: In front of Ciliary Body and behind Cornea; colored
Pupil: hole formed by iris that lets light into back of eye

9. b. Sensory cells & Neurons
3. Sensory Layer = RETINA
- Innermost layer
a. Pigmented layer
b. Sensory cells & Neurons
i) Sensory Receptor cells
(1) Rods
Location:
Function

10. (2) Cones BLUE GREEN RED Function: Densest in the center
Sensory Layer …
BLUE GREEN RED
(2) Cones
Function:
Densest in the center
Three types of cones
Different cones are sensitive to different wavelengths
Color blindness is the result of the lack of one cone type
560 nm
(red cones)
530 nm
(green cones)
420 nm
(blue cones)
Light absorption by cone populations
380
450
500
550
600
650
700
750
Wavelengths (nanometers)

11. Color Blindness = Lack of one or more cone types

12. ii) Bipolar Layer: in front cones and rods which
Retina …
Central artery and vein of retina
ii) Bipolar Layer: in front
cones and rods which
relay vision info to them
- neurons
iii) Ganglion Layer: in front
of Bipolar Layer which
relay vision into to them
- Neurons
Axons form:
- Optic Disc: round area where the optic nerve leaves the eyeball = BLIND SPOT
Cannot see images focused on the optic disc
Optic disc
Sclera
Optic nerve
Choroid

13. Ciliary body Vitreous humor in posterior segment Iris Retina Margin
of pupil
Choroid
Sclera
Aqueous humor
(in anterior segment)
Fovea centralis
Optic disc
Optic nerve
Lens
Cornea
Ciliary zonule
(b)
Figure 8.4b

14. Fovea centralis Macula Blood vessels Optic disc Retina Lateral Medial
Figure 8.8

15. C. Lens Biconvex crystal-like structure
Held in place by a suspensory ligament attached to the ciliary body

16. Lens … Cataracts: Clouding of the lens
Some congenital, most are related to age-related thick
and hard lens
+ Smoking & Sun

17. D. Two Segments and Fluids of the Eye Anterior Segment
Aqueous humor
Watery fluid
Helps maintain intraocular pressure
Provides nutrients for the lens and cornea

18. Posterior Segment Vitreous humor
Gel-like substance posterior to the lens
Prevents the eye from collapsing
Helps maintain intraocular pressure

19. E. Focusing
Light must be focused to a point on the retina for optimal vision
The eye is set for distance vision (over 20 feet away)
Accommodation—the lens must change shape to focus on closer objects (less than 20 feet away)

20. F. Eye Reflexes
Bright light causes pupils to constrict through action of radial, circular, and ciliary muscles
Viewing close objects causes accommodation
Viewing close objects causes convergence (eyes moving medially)

21. G. Disorders of the Eye
Emmetropia—eye focuses images correctly on the retina
Myopia
Hyperopia
Astigmatism

22. III. The Ear A. Introduction Houses two senses Hearing
Equilibrium (balance)
B. The ear is divided into three areas
External Ear
Middle Ear
Inner ear

23. External (outer) ear Middle ear Internal (inner) ear Vestibulocochlear
nerve
Auricle (pinna)
Semicircular
canals
Oval window
Cochlea
Vestibule
Round window
Pharyngotympanic
(auditory) tube
Tympanic
membrane
(eardrum)
Hammer (malleus)
Anvil (incus)
Stirrup (stapes)
External acoustic
meatus
(auditory canal)
Auditory ossicles
Figure 8.12

24. 1. The External Ear hearing only Structures: Auricle (pinna)
External acoustic meatus (auditory canal)
Narrow chamber in temporal bone
Ends = tympanic membrane
Air-filled

25. 2. Middle Ear
Auditory tube connecting middle ear with the throat
Allows for equalizing pressure when ___
Three bones (ossicles) in cavity
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
Function
Transmit Vibrations of sound to inner ear

26. 3. Inner Ear or Bony Labyrinth
Sense organs for hearing and balance
Bony chambers within the temporal bone
Bony & Membraneous Labyrinth
Internal (inner) ear
Vestibulocochlear
nerve
Semicircular
canals
Oval window
Cochlea
Vestibule
Round window

27. Semicircular canals Ampulla Vestibular nerve Vestibule (a)
BONY lABYRINTH
Ampulla
Vestibular nerve
Vestibule
(a)
Figure 8.14a

28. (3) Inner Ear or Bony Labyrinth … C. Physiology 1. Static Equilibrium
These receptors respond to angular or rotary movements and movements of head
Vestibular Apparatus: Equilibrium receptors
Semicircular Canals
2. Dynamic Equilibrium

29. Cupula of crista ampullaris
Endolymph
Flow of endolymph
Cupula of crista ampullaris
Cupula
Nerve
fibers
Direction of body movement
(b)
(c)
Figure 8.14b-c

30. 3. Hearing Cochlea– Organ of Corti
Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on temporal lobe
Vibrations from sound waves move a membrane

31. Perilymph in scala vestibuli Spiral organ of Corti Vestibular membrane
Temporal bone
Perilymph in scala vestibuli
Spiral organ of Corti
Vestibular
membrane
Afferent fibers
of the cochlear
nerve
Temporal
bone
Cochlear
duct (contains endolymph)
Perilymph in scala tympani
(a)
Figure 8.15a

32. Hair (receptor) cells of spiral organ of Corti Tectorial membrane
Vestibular membrane
Hair (receptor) cells of spiral organ of Corti
Tectorial membrane
Fibers of the cochlear nerve
Supporting cells
Basilar membrane
(b)
Figure 8.15b

33. Homeostatic Imbalances of the Ears-- DEAFNESS

34. END

35. Lacrimal sac Lacrimal gland Excretory ducts of lacrimal gland
Lacrimal canaliculus
Nasolacrimal duct
Inferior meatus
of nasal cavity
Nostril
(b)
Figure 8.2b

36. Excretory duct of lacrimal gland Lacrimal gland Conjunctiva Anterior
aspect
Eyelid
Eyelashes
Tarsal
glands
(a)
Eyelid
Figure 8.2a

37. II. The EYE Eyebrow Site where conjunctiva merges with cornea Eyelid
Eyelashes
Pupil
Palpebral
fissure
Lacrimal
caruncle
Lateral
commissure
(canthus)
Medial
commissure
(canthus)
Sclera
(covered by
conjunctiva)
Iris
Eyelid
Figure 8.1

38. Pigmented layer of retina
Neural layer of retina
Central artery and vein of retina
Optic disc
Sclera
Optic nerve
Choroid
(b)

39. humor (in anterior segment)
Sclera
Ciliary body
Choroid
Ciliary zonule
Retina
Cornea
Fovea centralis
Iris
Pupil
Optic nerve
Aqueous
humor (in anterior segment)
Lens
Scleral venous sinus
(canal of Schlemm)
Central artery and
vein of the retina
Vitreous humor
(in posterior segment)
Optic disc
(blind spot)
(a)
Figure 8.4a