Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fundamentals of Anatomy & Physiology SIXTH EDITION Frederic H. Martini PowerPoint ® Lecture Slide Presentation prepared by Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii Chapter 17, part 2 The Special Senses
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings retina Retina contains rods and cones Cones densely packed at fovea (center of the macula lutea) Retinal pathway Photoreceptors to bipolar cells to ganglion cells, to the brain via the optic nerve Axons of ganglion cells converge at blind spot (optic disc) Horizontal cells and amacrine cells modify the signal passed along the retinal neurons
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.6a Figure 17.6 The Organization of the Retina
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.6b, c Figure 17.6 The Organization of the Retina
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Ciliary body and lens divide the anterior cavity of the eye into posterior (vitreous) cavity and anterior cavity Anterior cavity further divided anterior chamber in front of eye posterior chamber between the iris and the lens Eye anatomy
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.8 Figure 17.8 The Circulation of Aqueous Humor
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Aqueous humor circulates within the eye diffuses through the walls of anterior chamber passes through canal of Schlemm re-enters circulation Vitreous humor fills the posterior cavity. Not recycled – permanent fluid Fluids in the eye
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Posterior to the cornea and forms anterior boundary of posterior cavity Posterior cavity contains vitreous humor Lens helps focus Light is refracted as it passes through lens Accommodation is the process by which the lens adjusts to focus images Normal visual acuity is 20/20 Lens
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.9 Figure 17.9 Image Formation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure Accommodation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure Visual Abnormalities
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Rods – respond to almost any photon Cones – specific ranges of specificity Visual physiology
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure Rods and Cones
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Outer segment with membranous discs Narrow stalk connecting outer segment to inner segment Light absorption occurs in the visual pigments Derivatives of rhodopsin Photoreceptor structure
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Photoreception Animation: Photoreception PLAY Figure 17.14a, b
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Photoreception Figure 17.14c, d
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure Bleaching and Regeneration of Visual Pigments
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Integration of information from red, blue and green cones Colorblindness is the inability to detect certain colors Color sensitivity
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Dark adapted – most visual pigments are fully receptive to stimulation Light adapted – pupil constricts and pigments bleached. retinal adaptation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Large M-cells monitor rods Smaller more numerous P cells monitor cones the visual pathway
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure Convergence and Ganglion Cell Function
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Vision from the field of view transfers from one side to the other while in transit Depth perception is obtained by comparing relative positions of objects from the two eyes Seeing in stereo
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure The Visual Pathways
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Input to suprachiasmic nucleus affects the function of the brainstem Circadian rhythm ties to day-night cycle, and affects metabolic rates Visual circadian rhythm