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2.2 Vision - Coggle Diagram

- - - - contains light sensitive pigment-rhodopsin (protein scotopsin)
      - exist in two isomeric according light sensitivity
      - contains 125 million rods in neuro-retina
      - ECF contains :arrow_up: concentraction of Na+ ions, :arrow_down: concentraction of K+ ions, but concentraction of Na+ :arrow_down:, concentraction of K+ :arrow_up: inside rod cells.
      - In resting phase, K+ tends to maove outside the rod cells creating slight ly -ve charge inside
      - Bleaching: When lights in rod cells, rhodopsin absorbs it and breaks into scotopsin and 11 cis-retinal
      - 11 cis-retinal absorb photon of light, activates scotopism into enzyme.
      - produces large amount of transducin, activating phosphodieterase
      - Phosphodieterase hydrolyses cGMP to cease the flow of Na+ ion inside rod cells
      - Hyperpolarized rod cells transmit the neural signal to bipolar cell.
      - Bipolar cell, amacrine cell, ganglion cell process the neural signal, generating action potential to transmit to brain via optic nerve.
    - - cone cells contain different photo-pigment and are sensitive to red, green and blue
      - Perception of color depends on a cone
      - contains 7 million cone cells
      - cone cells contain iodopsin as photo-pigment, composing 11 cis-retinal and photopsin
      - mix of all three color produce the perception of white and abscence of all color produce perception of black.