2. The brain’s processing of sensory input & motor output is cyclical rather than linear Sensations: stimulus to the brain Perceptions: interpretation of sensory info

3. Sensor Receptors: Exteroreceptors- detect stimuli outside the body -Heat -Light -Pressure -Chemicals Interoreceptors- detect stimuli within the body -Blood pressure -Body position

4. Sensory receptors transduce stimulus energy transmit signals to the nervous system Sensory Transduction Amplification Transmission Integration

5. Chemoreception -Taste -Smell Electromagnetic receptors -Photoreceptors -Infrared receptors -Lateral line -Electroreception Nocioceptors Mechanoreceptors: -Hearing -Balance Thermoreceptors

6. respond to chemicals in an aqueous solution food dissolved in saliva airborne chemicals dissolved in mucous membrane Taste and smell are involved with specific receptor cells called chemoreceptors

7. Chemoreception: Taste

8. Salty- metallic ions Sweet- sugar Sour- H + Bitter- alkaloid Why are they important?

9. Gustatory pathway: Facial nerve  (afferent) 2/3 anterior portion of tongue Glossophyngeal posterior 1/3 of tongue Vagus nerve- few taste buds on epiglottis an pharynx These afferent fibers synapse in medulla  thalamus  gustatory cortex in parietal lobes and fibers to hypothalamus in limbic system

11. Find a mate Detect food Moth Chemosense male

12. Jacobson’s organ: The tongue flicks out, picking up odors and carrying them to the roof of the mouth into contact this sensory receptor

13. Heat receptor: heat-detecting sensors concentrated as two large pits between their nostril and eyes Found in pit vipers, as well as some boas and pythons Detects small differences in temperature (as slight as 0.02 o C) Used to locate and capture warm-blooded prey at night.

14. Sensory receptors are categorized by the type of energy they transduce

15. A diversity of photoreceptors has evolved among invertebrates Eye cups are among the simplest photoreceptors –Detect light intensity and direction — no image formation. –The movement of a planarian is integrated with photoreception.

16. Image-forming eyes. –Compound eyes of insects and crustaceans. Each eye consists of ommatidia, each with its own light-focusing lens. This type of eye is very good at detecting movement.

17. Single-lens eyes of invertebrates such as jellies, polychaetes, spiders, and mollusks. –The eye of an octopus works much like a camera and is similar to the vertebrate eye.

18. Vertebrates have single-lens eyes Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Is structurally analogous to the invertebrate single-lens eye. Fig. 49.9

19. Fibrous tunic- sclera and cornea (outer most layer) Composed of dense avascular connective tissue

20. Vascular tunic- uvea: choroid, cilliary body, iris, pupil (middle layer) Choroid- rich vascular nutritive layer; contains a dark pigment that prevents light scattering within the eye Cilliary body- lens is attached; contains muscles that change the lenses shape Iris- pigmented ring of muscular tissue composed of circular and radial muscles reflex contraction of circular muscle in bright light (small dia of pupil) reflex contraction of radial muscle in dim light (large dia of pupil) Pupil- central hole in iris

21. Sensory tunic- retina (inner most layer) Photoreceptors: rods (dim light, contains pigment rhodopsin) and Cones (color vision, not evenly distributed, concentrated in fovea) Optic disc- blind spot because its where optic nerve leaves the eyeball (no rods or cones) Macula lutea- yellow spot, area of high cone Fovea centralis- in center of macula lutea, contains only cones, area of greatest visual acuity

23. Vitreous humor- behind lens, gel-like substance with fine collagenic fibrils imbedded in as viscous ground substance- binds with water transmits light supports the posterior surface of the lens and holds the neural retina firmly against pigmented layer contributes to intraoccular pressure, helping to counter act the pulling force of the extrinsic eye muscles

24. Aqueous humor- in front of lens, anterior segment, watery fluid Supplies cornea and lens with nutrients Helps to maintain the shape of the eye Produced and renewed every 4 hrs by the cilliary body

26. Lens- transparent biconvex structure, flexible Attached by suspensory ligaments to cilliary body focuses image onto retina changes lens thickness to allow light to be properly focused onto retina

27. Coarse Fixed Focusing Cornea Shape Cornea Shape Accommodation- adjust configuration of Lens Shape Lens Shape Pupil Size Pupil Size

28. refraction

29. Focusing on a Near Object

30. Focusing on a Far Object

31. Photoreceptors of the retina. –About 125 million rod cells. Rod cells are light sensitive but do not distinguish colors. –About 6 million cone cells. Not as light sensitive as rods but provide color vision. Most highly concentrated on the fovea – an area of the retina that lacks rods. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

32. The light-absorbing pigment rhodopsin triggers a signal-transduction pathway Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Rhodopsin (retinal + opsin) is the visual pigment of rods. The absorption of light by rhodopsin initiates a signal-transduction pathway. Fig. 49.13

33. Color reception is more complex than the rhodopsin mechanism. –There are three subclasses of cone cells each with its own type of photopsin. Color perception is based on the brain’s analysis of the relative responses of each type of cone. –In humans, colorblindness is due to a deficiency, or absence, of one or more photopsins. Inherited as an X-linked trait. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

35. The retina assists the cerebral cortex in processing visual information Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Visual processing begins with rods and cones synapsing with bipolar cells. –Bipolar cells synapse with ganglion cells. Visual processing in the retina also involves horizontal cells and amacrine cells.

36. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 49.15

37. Vertical pathway: photoreceptors  bipolar cells  ganglion cells axons. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

38. Lateral pathways: –Photoreceptors  horizontal cells  other photoreceptors. Results in lateral inhibition. –More distance photoreceptors and bipolar cells are inhibited  sharpens edges and enhances contrast in the image. –Photoreceptors  bipolar cells  amacrine cells  ganglion cells. Also results in lateral inhibition, this time of the ganglion cells. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

40. The outer ear includes the external pinna and the auditory canal. –Collects sound waves and channels them to the tympanic membrane. The mammalian hearing organ is within the ear Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

42. From the tympanic membrane sound waves are transmitted through the middle ear. –Malleus  incus  stapes. –From the stapes the sound wave is transmitted to the oval window and on to the inner ear. –Eustachian tube connects the middle ear with the pharynx. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

43. external auditory canal tympanic membrane eustachian tube malleus incus stapes round window oval window

44. The inner ear consists of a labyrinth of channels housed within the temporal bone. –The cochlea is the part of the inner ear concerned with hearing. Structurally it consists of the upper vestibular canal and the lower tympanic canal, which are separated by the cochlear duct. The vestibular and tympanic canals are filled with perilymph. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

46. Biology 100 Human Biology cochlea saccule utricle semicircular canals auditory nerve

48. –The cochlear duct is filled with endolymph. –The organ of Corti rests on the basilar membrane. The tectorial membrane rests atop the hair cells of the organ of Corti. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

50. From inner ear structure to a sensory impulse: follow the vibrations. –The round window functions to dissipate the vibrations. Vibrations in the cochlear fluid  basilar membrane vibrates  hair cells brush against the tectorial membrane  generation of an action potential in a sensory neuron. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

51. Fig. 49.18

52. Pitch is based on the location of the hair cells that depolarize. Volume is determined by the amplitude of the sound wave. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

53. Behind the oval window is a vestibule that contains the utricle and saccule. –The utricle opens into three semicircular canals. The inner ear also contains the organs of equilibrium Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

54. Static Balance – utricle and sacule Dynamic Balance- semicircular canals

56. (semicircular canal)

57. cupula hair cells Endolymph fluid Vestibular nerve fibers (semicircular canal)

59. The effect of gravitational pull on the macula receptor cell in the utricle

60. Fishes and amphibians lack cochleae, eardrums, and openings to the outside. –However, they have saccules, utricles, and semicircular canals. A lateral line system and inner ear detect pressure waves in most fishes and aquatic amphibians Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

62. Statocysts are mechanoreceptors that function in an invertebrates sense of equilibrium. –Statocysts function is similar to that of the mammalian utricle and saccule. Many invertebrates have gravity sensors and are sound-sensitive Fig. 49.21

63. Sound sensitivity in insects depends on body hairs that vibrate in response to sound waves. –Different hairs respond to different frequencies. Many insects have a tympanic membrane stretched over a hollow chamber. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 49.22

64. pores Detects weak magnetic fields produced by other fish