HW2_solutions - 1. (14 points) Name the types of...

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1. (14 points) Name the types of photoreceptors in the eye and describe their function. How do we see color in the environment around us? What is color-blindness? a. The two types of photoreceptors are rods and cones. Rods are more numerous (20:1 ratio, except in the fovea), are responsible for monochromatic nighttime vision and work well in low light levels and contain only one type of visual pigment (rhodopsin). Cones are responsible for high- acuity (sharper) and color vision and have three different pigments closely related to rhodopsin and which are excited by different wave lengths. Cones exist for red, green and blue light, though they are each stimulated by a range of light wavelengths. Color depends on the wavelength of light reflected by an object (white objects reflect most wavelengths, black objects absorb most wavelengths). Color-blindness is an inherited defect in one or more of the three types of cones and makes it difficult for an individual to distinguish certain colors. The most common type of color-blindness is red-green, where people cannot distinguish red and green. (Silverthorn p . 357) 2. You graduated from UT, went on to medical school and have become a successful opthamologist. A patient comes into your office because is concerned that he can’t read the board in his quantitative physiology class. You assess the patient’s visit and determine that his has a mild case of myopia with a slight astigmatism in one eye. Your patient hasn’t covered these conditions yet in physiology and gives you a look of terror! a. (6 points) Explain to your patient what myopia is and what astigmatism is. i. Myopia is near-sightedness. It occurs when the focal point falls in front of the retina. (Silverthorn p. 354). b. (6 points) Your patient gives a huge sigh of relief at your explanation. You go on to explain that myopia can be corrected with glasses or contact lenses. Explain how corrective lenses work. Why do you think contact lenses are so much thinner than glasses but can perform the same function (Hint: some online research might help)? i.
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HW2_solutions - 1. (14 points) Name the types of...

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