1. Special Senses

2. Senses
General Senses include temperature, pain, touch, pressure, vibration, and proprioception.
Special Senses include olfaction, gustation, equilibrium, vision, and hearing.

3. Types of Receptors
Mechanoreceptors—stretching, touch, pressure in autonomic NS structures (barorecpetors) and body position (proprioceptors)
Chemoreceptors--chemical—gustation, olfaction, and autonomic NS chemicals
Nociceptors--pain
Thermoreceptors--temperature
Photoreceptors--light--70% of all receptors

4. Taste (Gustation) closely associated with smell
Gustatory Organs (Taste Buds)
located along the surface in elevations called Papillae (10,000 or more)

5. Taste Buds Respond to dissolved chemicals 6 types of taste sensations
Sweet
Sour
Bitter
Salty
Umami
Water

6. Smell (Olfaction) Detect to 50 or more specific scents
Olfactory Organs in the upper wall of the Nasal Cavity
Bipolar neurons -- Receptor Cells --Olfactory Hair Cells
Mucous membranes trap particles

7. Smell (Olfaction) LowThreshold: amount needed for detection
Adaptation: time for decrease in sensitivity
First second or so about 50% gone
FYI: Usually in one minute even strong scents are no longer smelled

8. Sight (Vision) most complex of Includes eye, and accessory structures
over 70% of the sensory receptors in the body are photoreceptors for sight
Includes eye, and accessory structures

9. Accessory structures of the eye
Eyelid, eyebrow, eyelashes = protects
Exocrine glands
Conjunctiva=mucous membrane of the eyelid and eye
Helps moisten and lubricate the eyeball

10. Accessory Structures of the Eye
Lacrimal apparatus
Produces tears to keep eye moist
Drains through the nasal cavity

11. Accessory structures of the eye
Extrinsic muscle of the eye
6 muscles that move eyes

12. Tunics (layers) of the Eye
Fibrous Tunic = outermost layer
Sclera--forms most of the fibrous tunic--the white of the eye
Cornea-refracts light

13. Fibrous layer of the Eye (cont)
Cornea--transparent coat of iris--slightly bulged by aqueous humor (anterior cavity)
Most common transplant

14. Vascular Tunic Blood supply Choroid --thin posterior portion
Ciliary Body-thick anterior portion, attaches to lens with ligaments
Iris-colored portion

15. Pupil dilation and constriction
Iris = made of circular and radial smooth muscles
Pupil= hole in iris changes size according to light

16. Vascular Tunic (cont)
Lens--changes shape for close-up or long range—lens accommodation
Ligaments attached to ciliary body
Viterous Humor (fluid, body) looks like clear jelly
Holds retina in place

17. Nervous Tunic the inner layer of the eye
Retina = thin fragile layer of neurons (few mm thick)

18. Rods and Cones--neurons in retina
Rods = elongated dendrites--black and white and night vision
Cones = dendrites with tapered ends
color sensitive
Sharpens vision

19. Outer Ear direct sound waves toward the eardrum
Auricle = the outer portion
Auditory Canal = extends into temporal bone
Cerumen=ear wax-modified sweat glands-protection

20. Middle Ear air filled space Aka Tympanic Cavity Auditory Ossicles
smallest bones in the body
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)

21. Middle Ear (cont) Eustachian Tube = Middle Ear to the Pharynx (throat)
pressure equalization
Tympanic Membrane (Eardrum
vibrates

22. The Inner Ear hearing and equilibrium Cochlea (hearing)
Vestibule (balance)
Semicircular Canals (balance)

23. Cochlea FYI: resembles a snail shell
contains the Organs of Corti for hearing

24. Cochlea (cont) Winding canals
Contains perilymph and endolymph (fluids)
FYI: surrounded by bony labyrinth
FYI: Fluids aid in transmission of vibration

25. Hearing Organs--Organs of Corti
Vibrate to endolymph motion
Release neurotransmitters

26. Steps of Hearing 1. Sound waves into auditory canal
2. Eardrum vibrates
3. Ossicles vibrate and magnify sound

27. Steps of Hearing
4. Oval window vibrates causes fluids to vibrate

28. Steps of Hearing 5. fluids causes hair cells to vibrate
6. Vibration –neurotransmitter - auditory nerve - brain

29. Equilibrium (Balance)
Aided by receptor cells in the Inner Ear
Determined by body position and movement of head
Uses sight & neurotransmitters sent by semicircular canals and vestibule

30. Semicircular canals three loops
Ampulla at entrance of loops contain Cristae
Hair cells in Cristae release neurotransmitters
brain interprets & responds

31. Vestibule Vestibule: chamber between the cochlea & semicircular canals
contains perilymph and endolymph (bony labyrinth)

32. Vestibule cont Maculae =contain hair-like cells,
Otoliths on surface, move
Otoliths respond to gravity

33. END OF NOTES

34. DISEASES AND DISORDERS OF THE SPECIAL SENSES

35. Presbyopia
Lens looses ability to change shape
Usually caused by age

36. Myopia (near sighted) Caused by eye shape being too long
Causes light to focus in front of retina
Corrected with glasses or contacts

37. Hyperopia (far-sighted)
Caused by eye shape being shorter than normal
Causes light to focus behind the retina
Corrected with glasses or contacts

38. Cataracts Caused by clouding of the lens
Can be replaced with artificial lens

39. Conjunctivitis Caused by an infection of the conjuctiva
More commonly called “pink eye”

40. Conjunctivitis

41. Deafness
Two types:
Conductive: caused by blockages in the auditory canal
Caused by middle ear infections
Eardrum damage

42. Sensorineural deafness
Damage to auditory nerves
Cochlear malformation or damaged by infection
Brain damage in temporal lobe

43. Glaucoma Aqueous humor build up puts pressure on the retina
Can damage retina if not treated

44. Macular Degeneration
Section of the retina called the macula (large concentration of blood vessels) is damaged causing tunnel vision until vision is gone

45. Middle Ear Infection
Usually involves the eardrum being infection by bacteria or virus
Bacterial treated with antibiotics
Common in children

46. Strabismus Caused by weak eye muscles
Can be surgically corrected or by patching the good eye to encourage other eye to work properly

47. Tinnitis
Caused by improper discharge of electrical impulses of the Organs of Corti Hair cells

48. Vertigo Caused by otoliths improperly aligning with membranes
Causes dizziness and nausea