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NPB 101
Lecture 9
| Question | Answer |
|---|---|
| What is the cornea used for? | Focusing on a distance after 20 feet |
| What is the lens for? | Focusing on a distance before 20 feet |
| What is the ciliary muscle for? | To adjust the focus of the eye |
| What is the retina used for? | These are the cells that capture the light and transmit it into electrical signals |
| How does the light that hits the retina get transmitted into signals? | The darkness depolarizes the the cells, then the light hyperpolarizes the receptors. This leads to disinhibition of some bipolar cells and excitation of some ganglion cells. |
| What part does cGMP play in the eye? | In darkness the cGMP keeps an ion channel open at all times so that Na can flow in and out. In the light though cGMP changes conformation and the Na channel closes, causing the eye to hyperpolarize because K can still get in and out. |
| Why do we have multiple cones in our eyes? | Some of these cones absorb different wavelengths of light. |
| What are the four mechanisms we use to adjust our vision based on the amount of available light? | Adjust aperture, use different photoreceptors, spatial summation, and adjust the sensitivity (adjust retina, change what color looks like in the eye, pupil dilation) |
| What is the pupillary reflex? | In darkness and during a sympathetic nervous system reaction, the pupil lets the most light in. During parasympathetic situations in the day the pupil constricts, only letting some light in. |
| Be able to draw the pupillary reflex diagram and name each of the steps | 1: Light stimulates retinal ganglion cell 2: Some synapse on pretectal neurons 3: The send bilateral output to ANS 4: Pre-ganglionic fibers are in cranial nerves III 5: Post-ganglionic fibers innervate smooth muscles causing pupillary constriction. |
| What is the scoptic region? | The region on the graph where there is less light coming into our eyes. This is where the rods are used because they are more sensitive to light. |
| What is the photopic region? | The region on the graph that is very bright where the cones are used because they are less sensitive to the light |
| What is the mesopic region? | The region where on the graph where there is just enough light for both the rods and cones to be used. |
| How do rods and cones communicate with the ganglion cells? | Both the rods and the cones communicate with the same bipolar cells which then communicate with the ganglion cells. |
| How many rods are there in comparison to ganglion cells? Why is it this way? | There are thousands of rods to very few ganglion cells. This increases the sensitivity to light during the night time. |
| What is the purpose of the fovea? | It is the smallest reception field with the best resolution in the eye with only .2% of the surface area and 50% of the cones and ganglion cells |
Created by:
24rory
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