Vision Signal Transduction

Question 1

light

Answer 1

electromagnetic radiation between 400 and 700 nm in wavelength photo: elementary unit of light, the smallest amount we’d be able to detect shorter wavelength = higher energy, longer wavelength = lower energy

Question 2

Answer 2

Question 3

retina

Answer 3

where light is turned into a neural signal, images are projected upside down and backwards

Question 4

fovea

Answer 4

specifc region of retine with high resolution vision because (1) light can get through to photoreceptors more easily because there are less layers of cells and (2) there is less convergence from many photoreceptors

Question 5

optic nerve

Answer 5

axons travel to brain, no retina at start of optic nerve creates blind spot

Question 6

patway of light signal in retina

Answer 6

Question 7

types of photoreceptors

Answer 7

rods: long, cylindrical, mostly in periphery, 1000x more sensitive, see better in low light conditions, sensitive to most colors on light spectrum
cones: short, tapered, mostly in fovea, contain one of three types of photopigments (protein that detects light) in each cell, each sensitive to specific wavelengths- blue cones (430), green cones (530), red cones (560)

Question 8

transduction of light into a signal

Answer 8

photoreceptors depolarize and release NT in the dark because cGMP is present at night and binds to cGMP gated Na+ channels to open them. they hyperpolarize and do not release NT during the day because light ????