B1E

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  • Created by: ellxe
  • Created on: 10-04-16 09:43
What does the cornea do?
Refracts (bends) light into the eye
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What does the iris do?
Controls how much light enters the pupil
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What does the lens do?
Also refracts light, focusing it on the retina
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What is the retina?
The light sensitive part, covered in receptors called cones and rods
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What do rods do on the retina?
They are more sensitive in dim light but can't sense colour
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What do cones do on the retina?
They are sensitive to different colours but aren't good in dim light. (red-green colour blindness is a lack of certain cone cells)
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What do the optic nerve do?
Carries impulses from the receptors to the brain.
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How do you look at distant objects?
The ciliary muscle relaxes, allowing the suspensory ligaments to tighten. Makes the lens less rounded - less light refraction
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How do you look at near objects?
The ciliary muscle tightens, slackening the suspensory ligaments. Lens is more round - more refraction
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What is long-sightedness?
You are unable to focus on near objects. The lens doesnt bend enough or the eyeball is too short. Images are focused behind the retina.
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How can long-sightedness be corrected?
Convex lens
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What is short-sightedness?
You are unable to focus on distant objects. The lens bends too much or the eyeball is too long. Images are focused in front if the retina.
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How can short-sightedness be corrected?
Concave lens
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How does binocular vision help you judge depth?
You compare the images from each eye. The more different each image is, the nearer the object.
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What does the Central Nervous System consist of?
Brain and Spinal chord.
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What is the job of the CNS?
To coordinate information.
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What is a reflex action?
Automatic reactions. The brain isn't involved. The sensory neurone connects to a relay neurone in the spinal chord which links directly to the right motor neurone. It is much quicker than thinking about it.
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What are electrical impulses sent along?
The axon. It also has a sheath which is an electrical insulator to speed up the impulse.
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What are dendrites and what do they do?
Branched endings of neurones. They can connect to other neurones.
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What is a synapse and what happens there?
The connection between two neurones. Transmitter chemicals diffuse across the gap and then bind to the receptor molecules in the membrane of the next neurone.
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How do stimulant drugs affect the nerves?
They increase the amount of transmitter chemical at some synapses, increasing the frequency of impulses.
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How do depressant drugs affect the nerves?
They bind with the receptor molecules on the membrane of the next neurone blocking the electrical impulse.
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Other cards in this set

Card 2

Front

What does the iris do?

Back

Controls how much light enters the pupil

Card 3

Front

What does the lens do?

Back

Preview of the front of card 3

Card 4

Front

What is the retina?

Back

Preview of the front of card 4

Card 5

Front

What do rods do on the retina?

Back

Preview of the front of card 5
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