Concave lends focus further back Farsighted eyeball too short, light focuses behind retina. Iris regulates amount of light entering eye. Color from amount and kind of pigment present. 2 layers of muscle to contract or increase pupil size. 6 muscles from eyeball exterior to bones of orbital socket.
Cranial nerves move eyes together usually.
No receptors there. Nt release from amount of depolarization. Light hits rhodopsin, retinal changes shape to trans, rhodopsin breaks down. Less glutamate, so bipolar cell depolarizes, release NT that excites ganglion cell. Cone responds to range of wavelength, but most sensitive to one color.