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Neuro4
WVSOM -- Neuroanatomy -- Biochemistry of Vision
| Question | Answer |
|---|---|
| Refraction | bending of light at anangled surface |
| What happens to light when it hits a glass surface perpendicular to light rays? | does not bend |
| What does a convex lens do? | causes light rays to converge to a focal point |
| What will a concave lens do? | cause light rays to diverge |
| What does visible light range from? | 400nm – 700 nm |
| Rods | sensitive to light so good for dim light or night vision. Do not respond well to moving stimuli. Slow response time |
| Cones | not sensitive to dim light and respond quickly. Daytime vision and color |
| How many cones per eye? | 5 million |
| What are the 3 classes of cones? | Blue, green and red |
| What are blue cones for? | short wavelength |
| What are green cones for? | medium wavelengths |
| What are red cones for? | long wavelengths |
| What is photo pigment for? | responsible for absorbing the energy from the light into a cascade of events |
| Where aer the photo receptors at? | outer segments of the membranes |
| What does photopigment consist of? | retinal and opsin |
| What is retinal? | vit A derivative |
| What is opsin? | glycoprotein |
| How many opsins are there? | 4 – 1 for rods (scotopsin and then 3 in cones (red, green , blue) |
| What photopigment do rods have? | rhodopsin |
| What are photoreceptors in the dark? | at rest and somewhat depolarized |
| What happens to photoreceptors int eh presence of light? | hyperpolarizes |
| How do the photoreceptors stay depolarized? | Na+ channels open |
| How are Na+ channels in the dark? | open |
| How are Na+ chennels in the light? | closed |
| What gates are on Na+ channels? | cGMP |
| What reduces G-protein concentration? | transducin |
| How does transducin lower g-protein concentration? | by activating a phosphodiesterase which reduces cGMP |
| What is the phototranduction pathway? | light activates photopigment, activates tranducin, activates phosphodiesterase, reduces cGMP concentration, Na + chennels close and hyperpolarization occurs, glutamate release is reduced |
| What does phototransduction pathway cause? | amplification |
| What inhibits bipolar cells? | glutamate |
Created by:
tjamrose
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