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Sensory Receptor Cells of the Eye

Sensory Receptor Cells of the Eye. Sensory Neural Systems 22 January 2008 Rachel L. Leon. Eye Anatomy. http://www.matossianeye.com/art2/ANATONY2.jpg. http://www.deltagen.com/target/histologyatlas/atlas_files/sense/eye_retina_40X.jpg.

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Sensory Receptor Cells of the Eye

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  1. Sensory Receptor Cells of the Eye Sensory Neural Systems 22 January 2008 Rachel L. Leon

  2. Eye Anatomy http://www.matossianeye.com/art2/ANATONY2.jpg http://www.deltagen.com/target/histologyatlas/atlas_files/sense/eye_retina_40X.jpg http://scienceblogs.com/clock/2006/06/bio101_lecture_6_physiology_re.php

  3. Sensory Receptors of the Eye • Photopigment found in the modified cilia which contain disc membranes • Rods have rhodopsin, allow for scotopic vision • Cones have three types of photopigments, allow for photopic vision http://cas.bellarmine.edu/tietjen/images/Eyes!.htm

  4. Photoreceptors: Rod Cells http://cas.bellarmine.edu/tietjen/images/Eyes!.htm

  5. Phototransduction in Rod Cells • RGS9 bound to R9AP turns off response to light by increasing rate of GTP hydrolysis by transducin • Mutations in RGS9 or R9AP cause slow deactivation • cause difficulty in adjusting to changes in light levels, as well as in seeing low-contrast, moving objects http://www.nature.com/nature/journal/v427/n6969/fig_tab/427020a_F1.html

  6. Photoreceptors: Cone Cells • Three pigments • Max sensitivity 420nm, S pigment • Max sensitivity 530nm, M pigment • Max sensitivity 560nm, L pigment • Each cone only has one type of pigment • Receptive fields overlap, so the strength of response from each of the responding cone types allows identification of the wavelength http://www.giangrandi.ch/optics/spectrum/visible-a.jpg

  7. Retinal Processing • Simple version: photoreceptor  bipolar cells  ganglion cells • Ganglion cells are the first cells that produce an action potential • Cone pathway • Cones receive input from rods • Two subsets of bipolar cells: ON and OFF cells • Rod pathway • Bipolar cells are sign inverting, connect to amacrine cells • Amacrine cells  ganglion cells, cone bipolar cells http://www.mitre.org/news/the_edge/september_99/sep99_imgs/retina.jpg

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