Lec 5 vision Neuro 3206 Lec 5 vision-from light to photoreceptors

January 19, 2018 Off By admin
Question Answer what is the electromagnetic radiation 400-7000nm How are wavelength (1) t intensity(2) and purity(3) processed by the brain 1. colour
2.brightness
3.saturation In the perception of vision, what is the function of the cornea window In the perception of vision, what is the function of the crystalline lens focus In the perception of vision, what is the function of the pupil light enters In the perception of vision, what is the function of the iris regulates light In the perception of vision, retina contains rods and cone that receive image and snd to brain why is refraction important for the eye its necessary to focus light rays onto the retina what is the r. index of the cornea 42 diopters fixed What is the process in which the lens changes its shape to alter its refractive power (12 diopters) accommodation What occurs when the ciliary muscles relax and contact Relax- zonulens stretch-lens flat-distant objects how does the eye focus on a far object ciliary muscles relax–>zonules stretch–> lens flat how does the eye focus on a close object ciliary muscles contract–> reduce tension on zoniles–> lens bulged- What does emmetropia(1) , hyperopia(2) and myopia(3) mean 1.good vision
2. farsightedness
3.nearsightedness what occurs in the retina when your hyperopia light focused behind the retina what occurs in the retina when your mypoia light focused in front of the retina what occurs when your presbyopia lens becomes sclerotic and loses elasticity with age–> cant focus close objects–> how is prebyopia corrected bifocals what is the optic disk where arteries, veins, and axons enter and exit the eye explain the vascular tree spreeds across retina–>stops short of fovea Five layers that compose the retina (PBRHA) P-photoreceptor
B-bipolarcell
Rretinal ganglion cells
H-horizontal cells
A-Amacrine cells why are photoreceptors are at the back of retina? (hint-PE)** 1. beside the pigment epithelium because they provide critical metabolic support for the PR– the other cells are relatively translucent-light can go through minimal bending distortion what is special about the eye of cats and why their eyes shine in the dark eyeshine results from the reflective tapetum in cats what is the function of a photoreceptor cells in the retina that transduce light energy into neural energy what is the function of rods photoreceptors specialized for night vision
-no colour what is the function of cones PR specialized for DL vision,
-acuity and colour how many types of cones are there 3
SML cones whats the difference in rods and cones duplex retina Descrive outer segment n the PR -adjacent to pigment epithelium how long is the cycle of disk formation in the base of the outer segment at that is phagocytosed by pigment epithelium 12 Days which segment in the photoreceptor manufactures visual pigment proteins used in visual transduction inner is there a higher concentration of cones or rods in the fovea cones
bad perception of colour in periphery why is the fovea the main focus of the eye in light 1.In centre of field of vision
2. Axons of RCGs are thinnest over fovea- light is less distorted
3.cones density drops off with retinal eccentricity why does images degrade with eccentricity due to aberrations in cornea and lens what is the process of conversion of light to chemical and then electrical signals by rods and cones Phototransdution Name the process of how a phototransduction occurs light–> change in protein conformation–>Binds to GTP—> dec second messanger–> decrease Na+ conductance what happens when your eye is in the dark high levels of cGMP in outer segment