1. Memmler’s The Human Body in Health and Disease 11th edition
Chapter 11
The Sensory System

2. The Senses Sensory system detects environmental change
Environmental change initiates nerve impulse (stimulus)
Stimulus interpreted by cerebral cortex
Sensation experienced

3. Sensory Receptors 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

4. Question: Which sensory receptors respond to movement. a
Question: Which sensory receptors respond to movement? a. thermoreceptors b. photoreceptors c. mechanoreceptors

5. Answer: c. mechanoreceptors

6. The Eye and Vision Eye protection structures Eye cavity bones Eyelids
Eyelashes and eyebrow
Conjunctiva
Lacrimal glands

7. Checkpoint 11-1: What are some structures that protect the eye?

8. Coats of the Eyeball Eyeball has three separate coats (tunics) Sclera
Choroid
Retina

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

10. Checkpoint 11-2: What are the names of the tunics of the eyeball?

11. Pathway of Light Rays and Refraction
Transparent parts of the eye that refract light
Cornea
Aqueous humor
Crystalline lens
Vitreous body

12. Checkpoint 11-3: What are the structures that refract light as it passes through the eye?

13. Question: What is the name of the fluid within the eyeball. a
Question: What is the name of the fluid within the eyeball? a. aqueous humor b. vitreous c. sclera

14. Answer: a. aqueous humor

15. 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

16. Checkpoint 11-4: What are the receptor cells of the retina?

17. 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.

18. Muscles of the Eye
Two muscle groups adjust eye so retina can receive clear image

19. The Extrinsic Muscles Outer surface of eyeball Voluntary
Control convergence for three-dimensional vision

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

21. Checkpoint 11-5: What is the function of the extrinsic muscles of the eye?

22. The Intrinsic Muscles Within eyeball
Iris regulates amount of light entering eye
Ciliary muscle shapes lens for near and far vision

23. 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. 
ZOOMING IN
• What structures hold the lens in place?

24. Checkpoint 11-6: What is the function of the iris?
Checkpoint 11-7: What is the function of the ciliary muscle?

25. 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)

26. Nerves of the eye. 
ZOOMING IN
• Which of the nerves shown moves the eye?

27. Checkpoint 11-8: What is cranial nerve II and what does it do?

28. 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

29. Checkpoint 11-9: What are some errors of refraction?

30. The Ear Sense organ for hearing and equilibrium Outer ear Middle ear
Inner ear

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

32. The Outer Ear Pinna (auricle) Directs sound waves into ear
External auditory canal (meatus)
Ceruminous glands
Tympanic membrane
Vibrates as sound waves enter ear

33. Question: What is the anatomic name for the external part of the ear
Question: What is the anatomic name for the external part of the ear? (that funny-looking curved part that sticks out from the side of your head) a. malleus b. meatus c. pinna

34. Answer: c. pinna

35. The Middle Ear and Ossicles
Middle ear cavity contains ossicles (small bones) that amplify sound waves and transmit sounds to inner ear
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)

36. Checkpoint 11-10: What are the ossicles of the ear and what do they do?

37. Eustachian Tube Connects middle ear cavity with throat (pharynx)
Allows pressure to equalize on both sides of tympanic membrane
Continuous mucous membrane from pharynx to middle ear cavity

38. The Inner Ear Bony labyrinth Vestibule Semicircular canals Cochlea
Perilymph fluid
Membranous labyrinth
Endolymph fluid

39. 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.

40. Hearing Organ of Corti Located in membranous cochlea (cochlear duct)
Ciliated receptor cells
Tectorial membrane

41. Question: True or False: The cochlea is in the middle ear.

42. Answer: False: The cochlea is in the inner ear.

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

44. Checkpoint 11-11: What is the name of the organ of hearing and where is it located?

45. Equilibrium
Ciliated equilibrium sensory receptors are located in vestibule and semicircular canals
Types of equilibrium
Static
Maculae receptors
Otoliths fluid
Dynamic
Cristae receptors

46. 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.
ZOOMING IN • What happens to the cilia on the receptor cells when the fluid around them moves?

47. 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.

48. Checkpoint 11-12: Where are the receptors for equilibrium located?
Checkpoint 11-13: What are the two types of equilibrium?

49. Otitis and Other Disorders of the Ear
Otitis media
Otitis externa
Hearing loss
Conductive hearing loss
Sensorineural hearing loss
Presbycusis

50. Other Special Sense Organs
Taste and smell sense organs respond to chemical stimuli

51. 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)

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

53. 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)

54. Checkpoint 11-14: What are the special senses that respond to chemical stimuli?

55. The General Senses Receptors scattered throughout the body sense Touch
Pressure
Heat
Cold
Position
Pain

56. Sense of Touch Sense of Pressure Tactile corpuscles
Found mostly in dermis of skin and around hair follicles
Sensitivity varies with the number of receptors
Baroreceptors in walls of large arteries monitor blood pressure and trigger responses that control BP as vessels stretch.
Sense of Pressure
Receptors for deep touch located
In subcutaneous tissues
Near joints, muscles, and other deep tissues

57. Sense of Temperature Temperature receptors Are free nerve endings
Are widely distributed in the skin
Are separate for heat and cold
Occur in hypothalamus of brain
Help to adjust body temperature according to temperature of circulating blood

58. 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

59. Checkpoint 11-15: What are examples of general senses?
Checkpoint 11-16: What are proprioceptors and where are they located?

60. Question: Temperature receptors in what part of the brain regulate body temperature according to circulating blood temperature? a. hypothalamus b. medulla oblongata c. cerebral cortex

61. Answer: a. hypothalamus

62. Sense of Pain Pain receptors Are free nerve endings
Are found in skin, muscles, joints and (to a lesser extent) in most internal organs
Pain relief
Analgesic drugs
Anesthetics
Endorphins
Heat or cold
Relaxation or distraction techniques

63. Sensory Adaptation
Occurs when receptors are exposed to continuous stimulus
Some receptors can adjust themselves so sensation becomes less acute
Receptors adapt at different rates
Pain receptors do not adapt

64. End of Presentation