Neuro Chapter 9

Neuro Chapter 9 - Chapter 9 Properties of Light 1. Light a....

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Chapter 9 Properties of Light 1. Light a. Wavelength – distance between successive peaks or troughs b. Frequency - number of waves per second c. Amplitude – difference between wave trough and peak d. Radiation is proportional to its frequency e. Radiation emitted at high frequency (short wavelengths) has highest energy content f. Radiation at emitted at lower frequencies (longer wavelengths) has less energy 2. Optics a. Study of light rays and interactions is called optics b. Reflection – bouncing of light rays off a surface c. Absorption – transfer of light energy to a particle or surface i. Black absorbs energy of all visible wavelengths d. Refraction – bending of light rays that can occur when they travel from one transparent medium to another Structure of the Eye 1. Gross anatomy a. Pupil - opening that allows light to enter the eye and reach retina b. Iris – pigmentation provides what we call the eye’s color i. surrounds pupil ii. contains two muscles that can vary the size of the pupil c. cornea – glossy transparent external surface that covers iris and pupil d. sclera – the white of the eye, forms the tough wall of the eyeball e. Extraocular muscles – move the eyeball in the orbit f. Conjuctiva – membrane that folds back from the inside of the eyelids and attached to the sclera g. Optic nerve – carrying axons from the retina, exit the back of the eye, pass through the orbit and reaches the base of the brain near the pituitary gland 2. Ophthalmoscopic Appearance of the Eye a. Optic disk – pale circular region where optic nerve fibers exit retina i. Sensation of light cannot occur because no photoreceptors here 1. Neither near large blood vessels because they cause shadows on the retina b. Macula – part of the retina for central vision i. no large blood vessels in this region of the retina is one of the specializations that improves quality of central vision c. Fovea – dark spot about 2mm in diameter and retina thinner here than anywhere else i. convenient anatomical reference point 3. Cross-sectional anatomy of the eye a. Aqueous humor – fluid the nourishes the cornea
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b. Lens- suspended by ligaments (Called zonule fibers) attached to the ciliary muscles , which are attached to the sclera and form a ring inside the eye c. Vitreous humor – (viscous and jellylike) lies between the lens and the retina; its pressure serves to keep the eyeball spherical Image formation by the eye 1. refraction by the cornea a. Light rays that strike the curved surface of the cornea bend so that they converge on the back of the eye b. Those that enter the center of the eye pass straight to the retina c. Focal distance – distance from the refractive surface to the point where parallel light rays converge i. Depends on curvature of the cornea - the tighter the curve, the shorter the focal distance 2. Accommodation by the lens a. Lens involved more importantly in forming crisp images of objects located
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This note was uploaded on 04/17/2008 for the course NEURO 101 taught by Professor Mosh. during the Fall '08 term at NYU.

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Neuro Chapter 9 - Chapter 9 Properties of Light 1. Light a....

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