1. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings H UMAN P HYSIOLOGY Sensory Physiology equilibrium & vision

2. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Body balance Body position Body movement Propioceptors Vision Vestibular apparatus Equilibrium: Mechanoreceptor

3. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Organs of Equilibrium  Receptor cells are in two structures  Vestibule  Semicircular canals Figure 8.16a, b

4. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Organs of Equilibrium  Equilibrium has two functional parts  Static equilibrium – sense of gravity at rest  Dynamic equilibrium – angular and rotary head movements Figure 8.16a, b

5. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Static Equilibrium - Rest  Maculae – receptors in the vestibule  Report on the position of the head  Send information via the vestibular nerve  Anatomy of the maculae  Hair cells are embedded in the otolithic membrane  Otoliths (tiny stones) float in a gel around the hair cells  Movements cause otoliths to bend the hair cells

6. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Function of Maculae Figure 8.15

7. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Dynamic Equilibrium - Movement  receptors in the semicircular canals  Tuft of hair cells  Cupula (gelatinous cap) covers the hair cells Figure 8.16c

8. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Dynamic Equilibrium  Action of angular head movements  The cupula stimulates the hair cells  An impulse is sent via the vestibular nerve to the cerebellum Figure 8.16c

9. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Integration Medulla Cerebellum Thalamus Cortex Equilibrium: Mechanoreceptor Figure 10-26: Central nervous system pathways for equilibrium

10. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Otolith organs Gravity Calcite crystals Hair cells Semicircular canals Fluid moves Cristae Cupula Hair cells Equilibrium: Vestibular Apparatus

11. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Equilibrium: Vestibular Apparatus Figure 10-23a, b: ANATOMY SUMMARY: Vestibular Apparatus

12. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Equilibrium: Vestibular Apparatus Figure 10-23c, d: ANATOMY SUMMARY: Vestibular Apparatus

13. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The Eye and Vision  70 percent of all sensory receptors are in the eyes, only see 1/6 th of eye  Each eye has over a million nerve fibers  Protection for the eye  Most of the eye is enclosed in a bony orbit  A cushion of fat surrounds most of the eye

14. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Structures of the Eye  Eyelids  Eyelashes Figure 8.1b

15. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Structures of the Eye  Eyelashes =have modified sebacious glands produce an oily secretion to lubricate the eye Figure 8.1b

16. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Structures of the Eye  Conjunctiva  Membrane that lines the eyelids  Connects to the surface of the eye  Secretes mucus to lubricate the eye

17. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Structures of the Eye  Lacrimal gland  Tears: antibodies, lysozymes, stress? Figure 8.1a

18. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Extrinsic Eye Muscles  Muscles attach to the outer surface of the eye  Produce eye movements Figure 8.2

19. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structure of the Eye  The wall is composed of three layers  Sclera&Cornea fibrous outside layer  Choroid – middle layer  Sensory (retina) inside layer Figure 8.3a

20. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The Fibrous layer  Sclera  White connective tissue layer  Seen anteriorly as the “white of the eye”  Cornea  Transparent, central anterior portion  Allows for light to pass through  Repairs itself easily  The only human tissue that can be transplanted without fear of rejection

21. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Choroid Layer  Blood-rich nutritive layer  Pigment prevents light from scattering  Modified interiorly into two structures  Cilliary body – smooth muscle  Iris  Pigmented layer that gives eye color  Pupil – rounded opening in the iris

22. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sensory layer (Retina)  Contains receptor cells (photoreceptors)  Rods  Cones  Signals pass from photoreceptors and leave the retina toward the brain through the optic nerve

23. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neurons of the Retina Slide 8.11

24. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neurons of the Retina and Vision  Rods  Most are found towards the edges of the retina  Allow dim light vision and peripheral vision  Perception is all in gray tones

25. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neurons of the Retina and Vision  Cones – 3 types detect different colors  Most dense at the center of the retina  Fovea centralis – area of the retina with only cones  Lack of one type = color blindness  No photoreceptor cells are at the optic disk, or blind spot

26. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Lens  Biconvex crystal-like structure  Held in place by a suspensory ligament attached to the ciliary body Figure 8.3a

27. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Internal Eye Chamber Fluids  Aqueous humor in Anterior Segment  Watery fluid found in chamber between the lens and cornea  Similar to blood plasma  Helps maintain intraocular pressure  Provides nutrients for the lens and cornea  Reabsorbed into venous blood  Blocked drainage = glaucoma

28. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Internal Eye Chamber Fluids  Vitreous humor in Posterior Segment  Gel-like substance behind the lens  Keeps the eye from collapsing  Lasts a lifetime and is not replaced

29. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Lens Accommodation  Light must be focused to a point on the retina for optimal vision  The eye is set for distance vision (over 20 ft away)  The lens must change shape to focus for closer objects Figure 8.9

30. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Correcting the Eye Nearsightedness = myopia Focus of light in front of retina Eyeball too long or lens too thick Distant objects are blurry Farsightedness = hyperopia Focus of light beyond the retina Short eyeball or lens too thin Near objects are blurry.

31. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Correct focus

32. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

33. Hyperopia

34. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Astigmatism Unequal curvatures in cornea & lens

35. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reflected light translated into mental image Pupil limits light, lens focuses light Retinal rods and cones are photoreceptors Vision: Photoreceptors Figure 10-36: Photoreceptors in the fovea

36. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Rods – night vision Cones – color & details Bipolar & ganglion cells converge, integrate APs Photoreception and Local Integration

37. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Photoreception and Local Integration Figure 10-35: ANATOMY SUMMARY: The Retina

38. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Rod cells: monochromatic Cone cells: red, green, & blue Discs: visual pigments Pigmented epithelium Melanin granules Prevents reflection Retina: More Detail

39. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Retina: More Detail Figure 10-38: Photoreceptors: rods and cones

40. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Photons "bleach" opsin, retinal released, cascade, Na + channel closes, K + opens, hyperpolarization Reduces NT release Phototransduction

41. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Phototransduction Figure 10-40: Phototransduction in rods

42. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Bipolar Ganglion Movement Color Optic nerve Optic chiasm Optic tract Thalamus Visual cortex Vision: Integration of Signals to Perception Figure 10-29b, c: Neural pathways for vision and the papillary reflex

43. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sensory pathway: receptor, sensory neuron(s) & CNS Somatic senses: touch, temperature, pain & proprioception communicate body information to CNS Special senses: taste, smell, hearing, equilibrium, & vision Outside conditions for CNS integration into perception Receptors transduce mechanical, chemical or photon energy into GPs then to APs Summary