PSYB51H3 Chapter Notes - Chapter 2: Cornea, Photon, Crystallin
Document Summary
The first steps in vision: from light to neural signals: light form of electromagnetic radiation (energy produced by vibrations of electrically charged material) Most photons make it through the atmosphere and hit the surface of an object. If the ray of starlight strikes a light-colored surface, most light is reflected. Focusing light onto the retina: cornea, aqueous and vitreous humors help refract light, but the refractive power of these. 3 structures is fixed so they can"t bring close objects into focus. This job is performed by the lens: the lens can alter the refractive power by changing its shape, a process called accommodation, accommodation (change in focus) is done through contraction of the ciliary muscle. Lens becomes sclerotic (harder) and the capsule encircling the lens (enables it to change shape) loses elasticity: lens is normally transparent because the crystallins (proteins that make up lens) are packed together and are regular.
