Term
| What are the main parts of anatomy of the eye? |
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Definition
Sclera: the whites of the eye
Cornea: clear covering of the eye
Choroid: behind the retina-contains the blood vessels
Iris: Controls the Pupil
Cilliary Bodies: Control the shape of the lens
Retina: Contain Photoreceptors
Fovea Centralis: point of highest [cones]- greatest aquity
Vitreous Humor: give the eye shape
Optic Nerve |
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Term
| How many times does light get bent as it comes into the eye? |
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Definition
Twice
- Through the cornea
- Through the lens
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Term
| Why does the light bend (refract) when entering the eye? |
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Definition
| To focus it on the retina (Fovea Centralis) |
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Term
| What is the shape of the lens if it is focusing on something far away? |
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Definition
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Term
| What is the shape of the lens when it is focusing on something close up? |
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Definition
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Term
| What is it called when the lens changes shape in order to focus? |
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Definition
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Term
| What controls the shape of the lens? |
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Definition
The Cilliary Bodies
Relaxed: Flat lens
Contracted: Round lens (tension on the ligaments is released) |
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Term
| What is the technical name for farsightedness? |
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Definition
Hyperopia
Can see things far away best
Focal point is beyond the retina |
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Term
| What is the technical name for nearsightedness? |
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Definition
Myopia
Can see things close up better
Focal point doesn't reach the retina |
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Term
| What are the 4 layers of cells in the retina? |
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Definition
(Deepest to Topmost)
- Pigment Epithelium
- Photoreceptor Cells
- Bipolar Cells
- Ganglion Cells
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Term
| What is the Pigmented Epithelium? |
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Definition
- The base layer next to the choroid layer.
- It is dark in color to absorb extra light to help us see.
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Term
| What are the Photoreceptor Cells? |
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Definition
Cells that are responsible for the translation of light into electrical signals
(Rods and Cones) |
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Term
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Definition
- Cells that relay eletrical signals from the Photoreceptor cells to the ganglion cells.
- Act as a layer of regulation.
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Term
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Definition
- Primary Sensory Neurons
- Make up the Optic Nerve
- Synapse in the Thalamus
- Interneurons send signals to visual cortex
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Term
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Definition
- Receptors all along the membranes of the Rods that are sensitive to light
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Term
| What is Rhodopsin made up of? |
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Definition
Opsin - a Protein
Retinal - a Pigment |
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Term
| Retinal is ____ when no light is present. |
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Definition
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Term
| Retinal is ________ when light is present |
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Definition
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Term
| Light causes the ____________ of Retinal from Opsin |
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Definition
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Term
| What does the dissociation of Retinal from Opsin do? |
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Definition
- Activates the GPCR receptor
- Activates phosphadiesterase (enzyme)
- This causes the Rod cell's MP to become more negative
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Term
| Activation of Rhodopsin by light photons will most likely result in the _________ of _______ channels in the rod cells. |
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Definition
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Term
| What is the Dark Current? |
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Definition
| When no light is present, cells are depolarized and release a inhibitory NT on the Bipolar Cells. |
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Term
| What is the normal mV of a Rod cells Resting Membrane Potential? |
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Definition
-40mV
(which is above threshold) |
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Term
| Why is RMP of Rod Cells -40mV? |
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Definition
| Because Na+ channels are always open in the dark. |
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Term
| Walk through the steps of the Dark Current |
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Definition
- RMP = -40mV
- Na+ channels open
- Depolarization
- Release of Inhibitory NT
- No Action Potentials
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Term
| In low light, how do Rod Cells react? |
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Definition
- Rhodopisn is activated which activates Phosphodiesterase
- Na+ channels close and cell hyperpolarizes (-80mV)
- No depolarization- no release of Inhibitory NT
- Bipolar cells now free to release excitatory NT onto ganglion cells
- Ganglion Cells start AP
- AP to visual cortex = Image
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