BIOL 3402 Lecture Notes - Lecture 3: Mechanistic Organic Photochemistry, Ultraviolet, Stray Light
Document Summary
Over 1 million nerve fibers per eye. Protection: bony orbit, cushion of fat, tear ducts/glands. Sight: perception of objects by means of light they emit or reflect. Light: visible electromagnetic radiation: human vision: 400-700nm, light must cause photochemical reaction to produce nerve signal, ultraviolet radiation < 400 nm. Too much energy destroys macromolecules: infrared radiation > 700 nm. Too little energy to cause photochemical reaction: refraction: bending of light rays. Refraction index: how much it retards light rays relative to the air. The cornea refracts light more than the lens. Visual sent to occipital lobe: comes in upside down, 2 eyes = binocular vision. Sensory transduction in retina: retina converts light energy into action potential, pigment epithelium: posterior of retina. Neural components: photoreceptor cells: absorb light and generate chemical or electrical signal. Only rods & cones produce visual images. Light-absorbing cells: rods: night (scotopic) vision or monochromatic vision. Rhodopsin: visual purple: rods, opsin & retinal.
