Vision 1 light eye anatomy optics introduction to the retina 1 What does the visual spectrum refer to Even if we can t see it is there other electromagnetic radiation that we somehow respond to Know an example of an animal that uses more of the electromagnetic spectrum a Visual spectrum refers to light 1 Waves Pg 31 i Light is electromagnetic radiation made up of waves and particles oscillation that travels through a medium by transferring energy from one particle or point to another without causing any permanent displacement of the medium a Photon Pg 31 quantum of visible light or other form of electromagnetic radiation demonstrating both particle and wave properties i The more photons the brighter the light b Humans are only able to see visible light 380 760 nanometers light is only a small portion of the spectrum i Gamma rays radio and TV waves ii Infrared light we cant see it without night vision technology but pit vipers and rattle snakes use it to detect prey and predators iii Ultraviolet we don t see it but it causes sunburn 2 FYI of photons perception of intensity wavelength perception of color 3 Slide 5 know the terms in red a Radiance energy from the source intensity of a light beam i The sun radiates light b Illuminance falling on a surface area i The sun illuminates the earth energy from the source to the object the amount of light c Reflection Pg 32 especially light sound or heat usually back toward its point of origin to redirect something that strikes a surface If it looks lighter its reflecting most of the light usually happens if a surface is light colored to take up something such as light noise or d Absorption Pg 31 energy and not transmit it at all If a surface looks darker its absorbing most of the light usually with dark colored surfaces e Transmission Pg 32 to convey something from one place or thing to i i i another If the surface is translucent most of the light is being transmitted through it and some of it is refracted f Refracted Pg 32 to alter the course of a wave of energy that passes into something from another medium as water does to light entering it from there to measure the degree of refraction in a lens or eye i Bent 4 Know the parts of the eye Be able to label them on a picture and know what they each do a Cornea Pg 32 the transparent window into the eye i Its transparent because it contains no blood or blood vessels does have a large supply of transparent nerve endings which force the eyes to close and produce tears if scratched to preserve transparency 1 Nerves are from the afferent branch trigeminal nerve and the efferent branch facial nerve ii Light is transmitted and refracted through this iii Continuous with sclera which is a protective covering around the back of the eye b Aqueous humor Pg 33 watery fluid derived from blood immediately fills the space behind the cornea supplies oxygen and nutrients to and removes waste from the cornea and lens watery fluid in the anterior chamber of the eye i Helps maintain the shape of the eye and intraocular pressure too much production or too little drainage in the glaucoma c Lens Pg 33 the cornea has no blood supply so it can be completely transparent lens inside the eye that enables the changing of focus like i Bends the light that s passing through to eye to focus the image on the retina it bends light by bending itself 1 The ciliary muscles control the curvature of the lens ii Involved in accommodation near far focus d Pupil Pg 33 where the light enters the eye dark circular opening at the center of the iris in the eye i Dark circular opening at the center of the iris in the eye where light enters the eye size of the pupil determines how much light can pass e colored part of the eye consisting of a muscular diaphragm Iris Pg 33 surrounding the pupil and regulating the light entering the eye by expanding or contracting the pupil in the posterior part of the eye transparent fluid that fills the vitreous chamber f Vitreous humor Pg 33 i Longest part of the path to the eyeball the chamber compresses 80 of the internal volume a the eye generally transparent ii Refracts light and maintains the shape of the eye iii Floaters bits of bio debris that drift around in vitreous those random dust looking particles that you seen when its right before sunset g Choroid layer of blood vessels providing nutrition for the eye i Heavily pigmented so absorbs extraneous light entering the eye this reduces the reflection within the eye that would cause the image to blur 1 Also attached to the sclera h Retina Pg 33 light sensitive membrane in the back of the eye that contains rods and cones which receive an image from the lens and sends it to the brain through the optic nerve i Layer of tissue on the back portion of the eye like an outgrowth of the brain like embryonic tissue ii Nerve cells and photoreceptors absorb lights photons and transduce them into neural energy i Functions of the eye i Control light entry focus light on receptors transduction 5 What is the pupillary light reflex What cranial nerves are involved Why does red eye occur in photographs a Pupillary light reflex immediate constriction of pupil in response to bright light i Optic and oculomotor nerves b Red eye in dim light the pupil is dilated its reflected back from the fundus and through the choroid i The choroid is what gives the reflection of the red 6 What is accommodation how is it accomplished What shape do you need your lens flat or bulging to see close by What about to see far away What is presbyopia what causes it a Accommodation Pg 34 lens gets fatter bulging as gaze is directed toward nearer objects process by which the eye changes its focus the i Accomplished through the contraction of the ciliary muscle the lens is attached to the ciliary muscle through tiny fibers known as the zonules of zinn ii When the cilary muscle is relaxed the zonules are stretched and the lens is relatively flat in this state the eye will be focused on very distant objects but to focus on something closer the ciliary muscle must contract reduction the tension on the zonules allowing the lens to bulge b Presbyopia Pg 35 accommodation which makes it difficult to focus on near objects literally old sight age related loss of i Because the lens becomes sclerotic harder and the capsule that surrounds it loses its elasticity 7 What are cataracts What causes them How do they affect vision a Cataracts Pg 35 an opacity of the crystalline lens i The lens is transparent
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