BIO 240 1st Edition Lecture 33Outline of Last Lecture III. Visiona. Anatomy of the eyeb. Photoreceptorsc. Vision problemsOutline of Current LectureIII. VisionC. Physiology of sightIV. HearingA. Physiology of hearing B. Reflexes Current LectureIII. VisionC. Physiology of sight 1. 4 lux or higher of light are needed to form an image2. Light absorptioni. Retinal A light absorbing molecule that is capable of translating light into electrical signals. One of the main components of it is Vitamin A. ii. Opsin A protein that combines with retinal to form the four pigments of the eye. 1. Conesa. S-cones blueb. M-cones greenc. L-cones red2. Rodsa. Rhodopsin The purple pigment of rodsi. Accumulates in dim-light situations.ii. Requires very little light to stimulate rods.3. Light adaptation Abruptly going from dark to light. Results in a full bleaching of the rods, which causes a white blurry glare until the eyes adjust. 4. Dark adaptation Abruptly going from light to dark. At first the retina can form no images, rendering you temporarily blind. This is because there isn’t aThese 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.sufficient amount of light to stimulate your rods. Rhodopsin starts to quickly build up so that rods can do black and white vision. IV. Hearing A. Physiology of hearing Oval WindowVestibuleExternal Auditory MeatusLobeVestibular Membrane(Scala medi)B. Reflexesa. Tympanic reflex An adaptation to soften loud noises to protect the inner ear. Is subconscious, takes a second to occur. i. Stapedius A skeletal muscle (the smallest one in the body, and one that is involuntary) that attaches to the stapes and when contracted, pullsthe stapes away from the oval window. This dampens sound.ii. Tensor tympani A muscle that attaches to the malleus and pulls it medially during contraction to tense the tympanic membrane. b. READING ASSINGMENT – ON
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