1. Anatomy & Physiology II Chapter 11
4/21/2017 3:20 AM
The Senses
Anatomy & Physiology II
Chapter 11
© 2007 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

2. The Senses
Sensory receptors detect and respond to stimuli (environmental change)
Activation of receptors initiates nerve impulse (signal)
Signal interpreted by cerebral cortex
Sensation experienced

3. 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

4. Sensory Receptors Sensory receptors
Nociceptors – respond to tissue damage (painful stimuli)
Chemoreceptors - respond to chemicals
Photoreceptors - respond to light
Thermoreceptors - respond to heat
Mechanoreceptors - respond to movement

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

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

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

8. Pathway of Light Rays and Refraction
Transparent parts of the eye that refract light
Cornea
Aqueous humor
Lens
Vitreous body

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

10. 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.

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

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

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

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

15. Ciliary Muscle and Lens
Contraction of the ciliary muscle relaxes tension on the suspensory ligaments, allowing the lens to become more round for near vision. 

16. Nerve Supply to the Eye Optic nerve (cranial nerve II)
Oculomotor nerve (cranial nerve III)
Trigeminal nerve (cranial nerve V)
Trochlear (cranial nerve IV)
Abducens (cranial nerve VI)

17. Nerve Supply to the Eye • Which of the nerves shown moves the eye?
ZOOMING IN
• Which of the nerves shown moves the eye?

18. Errors of Refraction
Hyperopia (farsightedness) – difficulty focusing on objects near the face.
Myopia (nearsightedness) – difficulty focusing on distant objects.
Astigmatism - An irregular shaped cornea or lens prevents light from focusing properly on the retina. Images focus at muliple points on retina

19. Eye Disorders
Strabismus – inability to align both eyes simultaneously due to a lack of muscle coordination
Convergent (cross-eyed) – affected eye deviates toward nose
Divergent – affected eye deviates laterally
Amblyopia (lazy eye) – loss of vision in a healthy eye due to inadequate muscle balance
not correctable by glasses or contact lenses
The brain, for some reason, does not fully acknowledge the images seen by the amblyopic eye.

20. Other Eye Disorders Infections Injuries Cataract Glaucoma
Conjunctivitis
Inclusion conjunctivitis
Ophthalmia neonatorum
Injuries
Cataract
Glaucoma
Disorders involving the retina
Diabetic retinopathy
Macular degeneration

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

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

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

24. 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)

25. 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

26. The Inner Ear Bony labyrinth Membranous labyrinth Vestibule
Semicircular canals
Cochlea
Perilymph fluid
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. Hearing Organ of Corti Located in membranous cochlea (cochlear duct)
Ciliated receptor cells
Tectorial membrane

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

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

31. 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.

32. 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.

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

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

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

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

37. 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)

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

39. 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

40. 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

41. 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

42. Sense of Pain Pain receptors Pain relief 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

43. 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

44. End of Presentation