1. SPECIAL SENSES
“Bad men live that they may eat and drink, whereas good men eat and drink that they may live.”
Socrates
CHAPTER 11

2. Sensory Receptors Distribution of sense receptors
Special senses in sense organ
Vision
Hearing
Equilibrium
Taste
Smell
General senses throughout body
Pressure, temperature, pain, touch
Sense of position
Sensory receptors
Chemoreceptors-respond to chemicals
Photoreceptors-respond to light
Thermoreceptors-respond to heat
Mechanoreceptors-respond to movement

3. EYE PROTECTION STRUCTURES
Eye cavity bones
Eyelids
Eyelashes and eyebrow
Conjunctiva
Lacrimal glands

4. ANATOMY OF THE EYE MEDIAL & LATERAL CANTHUS
SPHERE OF 1 INCH IN DIAMETER
RESTS WITHIN A BONY ORBIT
CUSHIONED BY FAT
MEDIAL & LATERAL CANTHUS
MEIBOMIAN GLAND – OIL TO LUBRICATE EYELASHES
LYZOSYMES IN TEARS

5. The eye.
Note the three tunics, the refractive parts of the eye (cornea, aqueous humor, lens, vitreous body), and other structures involved in vision.

6. Light Pathway Structures
Cornea – transparent, clear; avascular; main area of refraction
Aqueous humor – watery fluid supporting cornea; gives it a curved look
Lens – biconvex; changes shape with eye focusing
Vitreous humor – gel like fluid; maintains shape of eyeball; aids in refraction

7. Structure of the Eyeball
Sclera (fibrous) – white of the eye; many nerve sensors for pain reception
Choroid (vascular) – dark brown pigmented layer; becomes ciliary body anteriorly
Retina (sensory) – light receptors
Rods
Cones

8. Function of the Retina Pigmented layer Sensitive to light Rods
Function in dim light
Shades of gray
Blurred images
Cones
Function in bright light
Color sensitive
Sharp images
Connecting neurons

9. Structure of the retina
Structure of the retina. Rods and cones form a deep layer of the retina, near the choroid. Connecting neurons carry visual impulses toward the optic nerve.

10. COLORS 3 TYPES OF CONES ABSENSE OF CONES = TOTAL COLOR BLINDNESS
RED
BLUE
GREEN
ABSENSE OF CONES = TOTAL COLOR BLINDNESS
MOST COMMON IS BLUE OR GREEN
X-LINKED TRAIT= SEEN IN MEN
MIX ALL THREE LIGHTS = WHITE
RED & BLUE = PURPLE

11. PATHWAY OF LIGHT
LIGHT COMES THROUGH PUPIL (cornea) TO LENS WHICH REFRACTS IT. LIGHT HITS PHOTORECEPTORS IN RETINA; RECEPTORS TRANSMIT ELECTRICAL SIGNALS VIA BIPOLAR CELLS TO GANGLION CELLS TO OPTIC NERVE TO VISION CENTER IN OCCIPITAL LOBE
PHOTORECPTORS ARE RODS AND CONES

12. MUSCLES OF THE EYE 6 EXTERNAL/EXTRINSIC MUSCLES Used for convergence
RECTUS MUSCLES
SUPERIOR
MEDIAL
LATERAL
INFERIOR
OBLIQUE MUSCLES

13. Extrinsic muscles of the eye. The medial rectus is not shown.
• What characteristics are used in naming the extrinsic eye muscles?

14. Intrinsic Muscles Used for accomodation Iris – 2 muscles around pupil
Circular muscle contracts = constriction
Radial muscle contracts = dilation
Ciliary Muscle – holds the lens suspends by suspensory ligaments

15. The ciliary muscle and lens (posterior view)
The ciliary muscle and lens (posterior view). Contraction of the ciliary muscle relaxes tension on the suspensory ligaments, allowing the lens to become more round for near vision. 
• What structures hold the lens in place?

16. TERMS OPTIC DISC – BLIND SPOT FOVEA CENTRALIS – ONLY CONES
LENS – BICONVEX CRYSTAL-LIKE
AQUEOUS HUMOR
VITREOUS HUMOR
SCLERAL VENOUS SINUS (CANAL OF SCHLEMM)
BLIND SPOT – WHERE THE OPTIC NERVE ENTERS THE BRAIN THERE ARE NO PHOTORECEPTORS
FOVEA CENTRALIS – AREA OF GREATEST VISUAL ACUITY; LATERAL TO EACH BLIND SPOT.
SCHLEMM – CORNER OF CORNEA AND SCLERA

17. IMBALANCES CATARACTS – LENS BECOMES HARDER AND OPAQUE
GLAUCOMA – INCREASED PRESSURE IN FRONT OF LENS CAUSES PRESSURE TO INCREASE AGAINST RETINA AND NERVE LEADING TO BLINDNESS
GLAUCOMA – GIVE MIOTIC TO INCREASE DRAINAGE FROM EYE

18. VISUAL FIELDS & PATHWAYS
OPTIC NERVE ENTERS BRAIN FROM EACH EYE
MEET AT OPTIC CHIASMA
MEDIAL FIBERS CROSS TO OPPOSITE PATHWAYS WHICH BECOME THE OPTIC TRACT
SYNAPSE AT HYPOTHALMUS TO FORM OPTIC RADIATION TO VISION CENTER

19. Nerve Supply to the Eye Optic nerve (cranial nerve II)
Ophthalmic branch of trigeminal nerve (cranial nerve V)
Oculomotor nerve (cranial nerve III)
Trochlear (cranial nerve IV)
Abducens (cranial nerve VI)

20. Nerves of the eye. 
• Which of the nerves shown moves the eye?

21. Errors of Refraction and Other Eye Disorders
Hyperopia
Myopia
Astigmatism
Strabismus
Convergent
Divergent
Amblyopia
Infections
Conjunctivitis
Inclusion conjunctivitis
Ophthalmia neonatorum
Injuries
Cataract
Glaucoma
Disorders involving the retina
Diabetic retinopathy
Macular degeneration

22. The ear. Structures in the outer, middle, and inner divisions are shown.

23. HEARING AND BALANCE OUTER EAR PINNA/ AURICLE EXTERNAL AUDITORY MEATUS
CERUMINOUS GLANDS
TYMPANIC MEMBRANE (EARDRUM)

24. MIDDLE EAR
TYMPANIC CAVITY FROM EARDRUM LATERALLY TO OVAL WINDOW AND ROUND WINDOW MEDIALLY
PHARYNGOTYMPANIC TUBE ( ALSO KNOWN AS EUSTACHIAN TUBE)
3 BONES – OSSICLES
MALLEUS
INCUS
STAPES
EAR INFECTIONS PREVENT THE MOTION OF THE OSSICLES WHICH LEADS TO DECREASED HEARING.

25. IMBALANCES
OTITIS MEDIA – MIDDLE EAR INFECTION RESULTING FROM BACTERIA IN SORE THROAT TRAVELING UP THE CANAL
MYRINGOTOMY – PLACING TUBES IN TYMPANIC MEMBRANE TO EQUALIZE THE PRESSURES BETWEEN MIDDLE AND OUTER EAR

26. INNER EAR OSSEOUS LABYRINTH MEMBRANOUS LABYRINTH VESTIBULE COCHLEA
SEMICIRCULAR CANALS
PERILYMPH FILLS THE BONY LABYRINTHS
MEMBRANOUS LABYRINTH
ENDOLYMPH FLUID

27. The inner ear. The vestibule, semicircular canals, and cochlea are made of a bony shell (labyrinth) with an interior membranous labyrinth. Endolymph fills the membranous labyrinth and perilymph is around it in
the bony labyrinth.

28. STATIC EQUILIBRIUM
MACULAE ARE SENSORY HAIRS EMBEDDED IN A BONY MEMBRANE WITHIN THE VESTIBULE
AS YOUR HEAD MOVES, THE OTOLITHS ROLL WITH GRAVITY, BENDING THE HAIRS
HAIR CELLS SEND AN IMPULSE DOWN THE NERVE TO BRAIN RELATING YOUR POSITION IN THE SPACE AROUND YOU

29. Action of the receptors (maculae) for static equilibrium
Action of the receptors (maculae) for static equilibrium. As the head moves, the thick fluid above the receptor cells, weighted with otoliths, pulls on the cilia of the cells, generating a nerve impulse.
What happens to the cilia on the receptor cells when the fluid around them moves?

30. DYNAMIC EQUILIBRIUM
RECEPTORS IN SEMICIRCULAR CANALS THAT RESPOND TO ROTATIONAL OR ANGLED MOVES
3 D PLANES IN SPACE
RECEPTOR REGION IS CRISTAE AMPULLARIS (HAIR CELLS IN A GEL LIKE CUPOLA {CAP})
BALANCE OCCURS ALONG WITH SIGHT & PROPRIOCEPTORS OF MUSCLES
CONSTANT RATE, STOPS SENDING MESSAGES UNTIL YOU STOP THEN TELLS YOU ABOUT IT.

31. Action of the receptors (cristae) for dynamic equilibrium
Action of the receptors (cristae) for dynamic equilibrium. As the body spins or moves in different directions, the cilia bend as the head changes position, generating nerve impulses.

32. Cochlea and the organ of Corti.
The arrows show the direction of sound waves in the cochlea.

33. HEARING
COCHLEAR DUCT IS FILLED WITH AN ENDOLYMPH- CONTAINING MEMBRANOUS LABYRINTH WHERE THE ORGANS OF CORTI ARE FOUND
ORGAN OF CORTI CONTAINS A BASILAR MEMBRANE WHERE THE HAIR CELLS (HEARING RECEPTORS) ARE POSITIONED

34. FOLLOW THE SOUND WAVE!!! SOUND WAVE ENTERS THE EAR CANAL
THE WAVE VIBRATES THE TYMPANIC MEMBRANE (EAR DRUM)
VIBRATION MOVES THE OSSICLES IN A LEVER FASHION, TRANSMITTING THE SOUND WAVE TO THE OVAL WINDOW
AGITATION OF THE WINDOW SETS FLUID IN INNER EAR INTO MOTION
CAUSES A PRESSURE WAVE ACROSS BASILAR MEMBRANE BENDING HAIRS

35. CONTINUED
THE HAIR CELLS IN ORGAN OF CORTI MOVE WITH THE WAVE WHICH CAUSES STIMULATION/ IMPULSE UP TO THE COCHLEAR NERVE THEN TO AUDITORY CENTER IN TEMPORAL LOBE
LENGTH OF HAIR CELLS DETERMINES FREQUENCY HEARD
SHORT = HIGH & LONG = LOW

36. ADAPTIONS CONTINUED INPUT LEADS TO “TUNING OUT”
****** HEARING IS THE LAST SENSE TO LEAVE OUR AWARENESS WHEN WE FALL ASLEEP, RECEIVE ANESTHESIA OR DIE******
BE CAREFUL WHAT YOU SAY!!!!

37. DEFICITS DEAFNESS – HEARING LOSS OF ANY DEGREE
CONDUCTION- CONDUCTON IS BLOCKED/ INTERUPTED
SENSORINEURAL – DAMAGE TO RECEPTORS, NERVE OR AUDITORY CORTEX
MENIERE’S DISEASE
CONDUCTION CAN USE A HEARING AID THAT WORKS ON BONE CONDUCTION PRINCIPLES
SENSORINEURAL – HEARING AIDS DON’T WORK WELL. COCHLEAR TRANSPLANTS ARE BEING DONE IF PROBLEM NOT IN THE AUDITORY CENTER
MENIERE – DEGENERATIVE LOSS – VERTIGO SEEN AS WELL AS LOSS OF HEARING

38. TASTE 10,000+ TASTE BUDS (RECEPTORS) IN ORAL CAVITY- MOST ON TONGUE
CHEMICALS DISSOLVE IN SALIVA
BATHE THE PAPILLAE WHERE THE GUSTATORY CELLS/ HAIRS ARE FOUND
TRANSMIT IMPULSE TO BRAIN

39. Sense of Taste Taste receptors (buds) on tongue
Stimulated by substance in solution
Basic tastes
Sweet
Salty
Sour
Bitter
Other tastes
Water
Alkaline
Metallic
Umami
Cranial nerves
Facial (VII)
Glossopharyngeal (IX)

40. Special senses that respond to chemicals.
UMAMI
Special senses that respond to chemicals.
(A) Organs of taste (gustation) and smell (olfaction).
(B) A taste map of the tongue.

41. 5 TYPES OF TASTE SWEET – RESPONDS TO OH- GROUPS SOUR – RESPONDS TO H+
BITTER – ALKALOIDS
SALTY – METALS
UMAMI - GLUTAMATES
EAT SUGAR AND SALT TO GIVE CARBS AND MINERALS
SOURS GIVE VITAMIN C
UMAMI – BODYS CRAVE FOR MEAT
BITTER ARE USUALLY POISONOUS OR SPOILED – PROTECTIVE TO NOT LIKE THESE

42. Sense of Smell Smell receptors in nasal cavity
Stimulated by substances in solution in nasal fluids
Smells stimulate appetite and flow of digestive juices
Olfactory nerve (cranial nerve I)

43. OLFACTORY OLFACTORY RECEPTORS IN ROOF OF NOSE
CHEMICALS DISSOLVED IN THE FLUID/ MUCUS STIMULATE THE OLFACTORY HAIRS AND THEN OLFACTORY RECEPTOR CELLS (NEURONS) SEND IMPULSE UP OLFACTORY NERVE TO CORTEX IN BRAIN
RECOGNITION OF SMELLS IS LINKED TO LIMBIC SYSTEM & EMOTIONS WHICH IS WHY THERE ARE CERTAIN SMELL THAT “REMIND US” OF WARM HAPPY TIMES, AWFUL TIMES ETC.

44. ADAPTIONS FREQUENT INPUT OF AROMA CAUSES “TUNING OUT”
ANOSMIAS – LOSS OF SMELL
OLFACTORY AURAS
HAVING A COLD, A HEAD INJURY OR AGING CAN CAUSE A LOSS IN SMELL ABILITY = DANGEROUS BECAUSE CAN’T TELL IF FOOD IS BAD, SMELL SMOKE, BURNT TOAST, ETC
OLFACTORY AURAS – SENSATION OF SMELLING SOMETHING BEFORE A SEIZURE OCCURS. Electrical activity before a seizure triggers a remembered smell.

45. FACTORS AFFECTING TASTE
SMELL AND TASTE CLOSELY RELATED
TEMPERATURE
TEXTURE
ODOR
SPICINESS
APPEARANCE

46. SENSORY IMBALANCES STRABISMUS PRESBYOPIA PRESBYCUSIS
STRABISMUS – CROSSED EYES; 20/20 VISION AROUND 7
PRESBYOPIA – FAR SIGHTED NESS OF AGING
PRESBYCUSIS –HEARING LOSS IN SIXTIES DUE TO OTOSCLEROSIS

47. Sense of Position Proprioceptors (position receptors)
Are located in muscles, tendons, joints
Relay impulses of body parts in relation to each other
Send impulses to the cerebellum for coordination
Help maintain equilibrium

48. Questions, anyone?