Chapter 10

1. Chapter 10 Somatic and Special Senses

2. Introduction to the Senses: Objective #1: List 5 types of Sense Receptors Types of Receptors 1. Chemoreceptors- taste and smell 2.Pain receptors-respond to tissue damage 3. Temperature- detect hot and cold. 4. Mechanoreceptors- detect pressure ..in skin and blood vessels 5. Photoreceptors- respond to light

3. Objective #2: Describe what sensations are A sensation is-a feeling which occurs when a sensory impulse is interpreted by the brain Projection of a sensation occurs when the brain sends the sensation back to the receptor

4. Phantom painoccurs when arms or legs have been lost and the person feels pain in area even though it is not there….the stump is generating impulses and the brain projects feeling back to area of missing limb • Sensory Adaptation- occurs when the receptor gets tired of sending impulses due to overstimulation. • Examples of Adaptation- 1. nose ..something when you enter a room smells bad…after a while…you do not smell it. 2. Jumping into a cold swimming pool..it seems warm after awhile.

5. Objective #3: Describe the somaticsenses Types of Somatic Senses (3 types) • Touch and Pressure receptors a. Sensory nerve fibers- light touch and pain…located in the epidermis b. Meissner’s corpuscle receptors- light touch- located in the upper dermis

6. c. Pacinian corpuscles – respond to heavy pressure…located deep in the dermis

7. Light touch receptors are Meissners Pain receptors are sensory fibers Strong pressure are Pacinian

8. Sense-Sational Facts! • The least sensitive area of your body is the middle of your back. • The most sensitive areas of your body are your hands, lips, face, neck, tongue, fingertips, and feet. • There are about 100 touch receptors in each of your fingertips.

9. 2. Temperature Receptors a. Hot receptors b. Cold receptors

10. 3. Pain receptors a. Not found in brain-headaches due to pain receptors in blood vessels b. Referred pain-appears to be coming from another part of the body other than the one which is being stimulated…during a heart attack…left arm may ache…both arm nerve pathway and heart nerve pathway combine at spine and brain does not know which area sent the impulse…projects pain back to wrong one…the arm

11. Notice that two nerves go to the spine …but only one nerve goes to the brain

12. Special Senses Objective #4: Describe what makes up the sense of smell 1. cilia-hair-like 2. olfactory receptors cells 3. olfactory bulb 4. olfactory tract….leads to brain

13. How the sense of smell works: • Olfactory receptor cells are located in epithelium in the roof of the nasal cavity. • Chemicals that you smell bind to receptor’s cilia creating nerve impulses that go to brain cont.

14. The odor that you smell is determined by the type of olfactory cells stimulated. • The effects of smell and taste combine.

15. Olfactory Sense Pathway of smell- cilia-to olfactory receptor-to olfactory bulb-to olfactory tract- to brain

16. Your Sense of Smell • When you smell something like roses for example you smell tiny things called odor particles. There are millions of them floating around waiting to be sniffed. • Our sense of smell is connected well to our memory. For example, the smell of popcorn can remind you of being at the movies with a friend. • Humans have seven primary odors that help them determine objects.

17. Sense-Sational Facts! • Dogs have 1 million smell cells per nostril and their smell cells are 100 times larger than humans. • People who cannot smell have a condition called Anosmia. • If your nose is at its best, you can tell the difference between 4000-10,000 smells. • As you get older your sense of smell gets worse. Children are more likely to have better sense of smell than their parents or grandparents.

18. Objective 5: Explain the sense of taste The sense of taste is know as gustation The bumps on your tongue are papillae…not taste buds! Taste buds are found in the papillae Taste buds contain the following: • Taste hairs 2. Taste sense receptors

19. Your taste buds can recognize four basic kinds of tastes: sweet, salty, sour, and bitter. • Have you ever thought about why foods taste different? • Your tongue and the roof of your mouth are covered with thousands of tiny taste buds. The receptor cells located in your taste buds send messages through sensory nerves to your brain and your brain tells you what flavors you are tasting. • Your taste buds can recognize four basic kinds of tastes: sweet, salty, sour, and bitter.

20. Complete view of sense of taste

21. A taste bud, protruding into a crevice between papillae. • Some fish have taste buds all over their body. Some insects have taste buds on their feet.

22. Sense-Sational Facts! • We have almost 10,000 taste buds inside our mouths; even on the roof of our mouths. • Insects have the most highly developed sense of taste. They have taste organs on their feet, antennae, and mouthparts. • In general, women have more taste buds than men. • Taste is the weakest of the five senses.

23. Obj. 6 Explain the Sense of Hearing Ear – organ of hearing • 3 Sections • External • Middle • Inner

24. Your ears serve two very important purposes. They help you hear and they help you keep your balance. When an object makes a noise, it sends vibrations speeding through the air. These vibrations are funneled into your ear canal by your outer ear. Then the vibrations hit your eardrum that is located in your middle ear and cause it to vibrate. The vibration goes through several other places then the auditory nerve carries the messages from 25,000 receptors in your ear to your brain. Your brain makes sense of the messages and tells you what sounds you are hearing. Your Sense of Hearing

25. The ear

26. External Ear • 1.auricle- collects sound waves • 2. external auditory meatus • lined with ceruminous glands • carries sound to tympanic membrane • terminates with tympanic membrane • 3. tympanic membrane (eardrum • vibrates in response to sound waves 12-25

27. Middle Ear • 1. tympanic cavity • air-filled space in temporal bone • 2.auditory ossicles • vibrate in response to tympanic membrane • malleus, incus, and stapes • 3.oval window • opening in wall of tympanic cavity • stapes vibrates against it to move fluids in inner ear 12-26 12-26

28. 4. Eustachian tube • connects middle ear to throat • helps maintain equal pressure on both sides of tympanic membrane • usually closed by valve-like flaps in throat

29. Inner Ear • 3 Parts: • cochlea • functions in hearing • semicircular canals • functions in equilibrium • vestibule • functions in equilibrium 12-29

30. 3 parts of the cochlea • 1. Scala vestibuli canal • upper canal • leads from the oval window • 2.Scala tympani canal • lower canal • leads to the round window • 3. Cochlear canal • in between the scala vestibuli • and scala tympani • Contains the Organ of Corti

31. Organ of Corti • Made up of the following parts: • Basilar membrane- membrane which moves up and down due to fluid flowing in the scala tympani • Hair cells- attached to the basilar • membrane. • 3. Tectorial membrane- does not move. Hair cells bend into it as they move up and down which creates electrical impulses

32. How Sound Travels Through The Ear... • Sound waves caught by the pinna enter ear canal. • Sound waves strike the tympanic membrane, causing it to vibrate like a drum, and changing sound waves into mechanical energy. • The malleus, incus, and stapes vibrate • The stapes moves in and out of the oval window of the cochlea creating a fluid motion. • The fluid movement within the cochlea causes membranes in the Organ of Corti to shear against the hair cells. • This creates an electrical signal which is sent via the Auditory Nerve to the brain, where sound is interpreted!

33. Cancer and Tumors Cancerinvolving the pinna

34. More TM Perforations The top slide shows an example of a small non-healing perforation in the pars tensa The bottom slide shows a larger defect in the pars tensa

35. Serous Otitis Media-middle ear infection

36. Sense-Sational facts! • Children have more sensitive ears than adults, and can recognize a wider variety of noises. • Dolphins have the best sense of hearing among all animals. They can hear 14 times better than humans. • Animals hear more sounds than humans. • When you go up high elevations, the change in pressure causes you ears to pop.

37. Obj. 7: Explain the Sense of Equilibrium • Static Equilibrium • vestibule • sense position of head when body is not moving • Dynamic Equilibrium • semicircular canals • sense rotation and movement of head and body

38. Obj. # 8: Explain the sense of sightAccessory organs: Tear glands • lacrimal gland-tear gland • located above eye • secretes tears • canaliculi • collect tears • people sometimes believe that tears come out here This is really the drainage hole for tear. • lacrimal sac • collects from canaliculi • nasolacrimal duct • collects from lacrimal sac • empties tears into nasal cavity-this is why one sniffles when they cry!

39. Obj. Structure of the Eye • hollow • spherical • wall has 3 layers • outer fibrous layer • middle vascular layer • inner nervous layer

40. Outer Tunic 1.Cornea • clear window of eye • covers pupil • light transmission • light refraction • contains no blood vessels 2.Sclera • Whites of eyeball • protection Sc

41. Pink eye • The sclera blood vessels are dilated and broken.

42. Rarely, the sclera grows over the cornea when the fetus is developing

43. Middle Layer • Iris • pigmented • controls light intensity • Ciliary body • holds lens in place • moves lens for • focusing • 3. Choroid coat • provides blood supply

44. Anterior part of eye • filled with aqueous humor

45. Lens of the eye Characteristics of the lens 1. transparent • biconvex • lies behind iris • largely composed of lens fibers 5. elastic- bends easily 6. held in place by ciliary muscle

46. Normal Vision Cataracts A cataract is a painless, cloudy area in the lens of the eye. A cataract blocks the passage of light from the lens to the nerves at the back of the eye, and it may cause vision problems. Changes in the lens of the eye are part of the aging process but normally do not develop into cataracts. However, cataracts are very common in older adults. Cataracts can also occur after an eye injury, as a result of eye disease, after the use of certain medications or as a result of medical conditions such as diabetes.

47. Cataracts are caused by clouding of the lens….can occur in children http://oftalmologo.bravepages.com/Leucocoria%201.jpg

48. Inner Tunic • 1.retina • contains visual receptors • rods for night vision and cones for day vision • 2.macula lutea – yellowish spot in retina… • 3.fovea centralis – center of macula lutea; produces sharpest vision…contains the most cones • 4.optic disc – blind spot; contains no rods or cones • 5. vitreous humor – thick gel that holds retina flat against choroid coat…fills posterior part of eyeball

49. Focusing On Retina • as light enters eye, it is refracted by • convex surface of cornea • convex surface of lens • image focused on retina is upside down and reversed from left to right

50. Clinical Application Refraction Disorders • concave lens corrects nearsightedness…lens thick on the sides and thin in the middle • convex lens corrects farsightedness….lens are • Thin on the side and thick in the middle 12-66