Bio2 Lecture 7

Bio2 Lecture 7 - Bio2 Lecture 7 Photoreceptors following...

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2/8/05 Photoreceptors - following the path light goes - - Choroid layer also serves as a protective tissue, and is before the scelera - Ganglion cells have long axons that pass across the surface of the retina and coalesce in one place to form the optic nerve - The optic nerve then takes impulses to the brain - Horizontal cells is for lateral integration - Light first passes rods - When rods are not stimulated by light, they are just sitting their in the dark leaking out inhibitory neuro transmitters, so action potentials are not going to the brain - Rods have a pigment called rhodopsin , which can absorb light energy, and breaks down to its 2 components o Auxin a protein o Retinal a derivative of vitamin A o When rhodopsin breaks down, it causes the rod cell to stop leaking out the neuro-transmitters so impulses will go to brain o When you rub your eyes, you see colors etc, because the pressure on the retina cause the rod cells to have action potentials going to the brain o Rods are for black and white - Cones are for color o 3 main types of cones o Red cones – absorb red better than any other cone o Green cones – “ o Blue cones “ o All have their own type of rhodopsin o Yellow light stimulates green cones and red cones - Rods are not even distributed in retina, they are distributed on the periphery, so fewer rods in center - Cones are more abundant in center - Macula – region in center of the eye o region in center of macula is fove a centralis where it 100% cones - We also have a blind spot o Where all of the axons of ganglion cells coalesce to form the optic nerve Mechanoreceptors (ear) - For sound reception as well as balance - Outer ear has a pinna, which helps to funnel the sound waves into the ear - Directs sound to ear drum tympanic membrane - Sound waves reach area outside inner ear which causes 3 bones to vibrate called
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This note was uploaded on 08/10/2009 for the course BIO 102 taught by Professor Brey during the Spring '08 term at Rutgers.

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Bio2 Lecture 7 - Bio2 Lecture 7 Photoreceptors following...

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