BIO 240 1st Edition Lecture 32 Outline of Last Lecture II Neurophysiology A Electrochemical Equilibrium Resting Potential B Anatomy of Neurophysiology C Graded Potentials D Action Potential III Vision A Anatomy of the eye Outline of Current Lecture III Vision a Anatomy of the eye b Photoreceptors c Vision problems Current Lecture III Vision A Anatomy of the eye i Choroid Middle layer of the eye that is highly vascularized with blood vessels ii Retina Movie screen where photoreceptors rods and cones are Innermost layer of the eye iii Anterior cavity Front of the cornea to the back of the lens Contains aqueous humor 1 Anterior chamber Front of the anterior cavity 2 Posterior chamber Back of the anterior cavity iv Posterior cavity Back of the lens to the end of the eyeball Contains vitreous humor v Aqueous humor Clear liquid vi Vitreous humor Jelly like substance Functions to press on the back of the retina to keep it smooth and without any wrinkles vii Optic nerve Sticks off of posterior aspect of the eye Receives input from the photoreceptors of the retina viii Cornea The anterior clear covering of the iris and the pupil Is for protection These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute ix Sclera The outermost layer of the eye made of fibrous connective tissue The white part of the eye x Ciliary body and Suspensory ligaments Work together to change the shape of the lens and hold then lens in place xi Lens Biconvex structure that functions to focus images on the retina xii Iris Pigment containing structure of the eye Gives you your eye color Only one pigment is found in the eye it is brown in color and the amount deposited determines eye color xiii Pupil The round opening in the iris that controls light coming into the eye xiv Pupillary constrictor Smooth muscle that helps to control the diameter of the pupil constricts to decrease the diameter xv Pupillary dilator Contractile epithelial cells also called myoepithelial cells contract around the pupil to increase its diameter xvi Fovea centralis Posterior area on the retina that has the highest visual acuity It is concentrated about the optic disc embedded in the retina For color vision There is a very high concentration of cones here xvii Optic disc Blind Spot Area just anterior to the optic nerve that contains no photoreceptors You can t see anything if an image is projected here xviii Panoramic vision A wide field of view If a species has really good panoramic vision they tend to loose depth perception xix Binocular vision A limited field of view but excellent depth perception xx Tapetum Lucidum Reflective tissue embedded behind the retina to catch and reflect light back to the retina Not present in humans helps with night vision is what makes the eyes of animals shine at night B Photoreceptors i Rods Photoreceptors for dim light and peripheral vision Images are not sharp Are located in the peripheral area of the retina which is why they help with peripheral vision 1 Rhodopsin The purple pigment found in rods ii Cones Photoreceptors for bright light vision and provide high visual acuity For color vision and very sharp focus Images will be clear as long as there is enough light 1 S cones Short light wavelengths of light Used to be called blue cones they see all the colors with short wavelengths 2 M cones Medium light wavelengths of light Used to be called green cones they see all the colors with medium wavelengths 3 L cones long light wavelengths of light Used to be called red cones they see all the colors with long wavelengths C Vision Problems i Color blindness A genetic disorder that is X linked 8 10 of males have it Is due to a lack of one or more cone types most commonly red green cones ii Myopia Nearsightedness Distant objects focus in front of the retina making them appear blurry A concave structure is used to correct making the light reach further iii Hyperopia Farsightedness Distant objects focus beyond the retina A convex lens is used to correct making the light stop shorter iv Glaucoma When pressure within the eye compresses the retina or the optic nerve It can lead to blindness v Cataracts A hardening or a clouding up of the lens Leads to foggy vision Easily treatable with vitamin C the effects can even be reversible Age dependent disease vi Astigmatism A condition caused by unequal curvatures in the cornea or the lens Bends the light causing vision problems