The brain and the eye B10

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What does the brain control?
Complex behaviour
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The brain is made of billions of interconnected _______ and it has different regions which carry out different _________
The brain is made of billions of interconnected NEURONES and it has different regions which carry out different FUNCTIONS
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Name three parts of the brain
-Cerebral cortex
-Cerebellum
-Medulla
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Cerebral cortex - where and function?
Highly folded outer part of the brain

Functions - language, memory, consciousness
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Cerebellum - where and function?
Towards the back near the bottom

Functions - controls our balance and co-ordinates our movements
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Medulla - where and function?
Bottom middle

Functions - controls our heart and breathing rate
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Why is it difficult to investigate the brain and treat brain diseases?
-Brain is protected by the scull which makes it tricky to access
-Structures of the brain are extremely complex, so it is difficult to work out exactly which parts if the brain carry out different functions
-Brain is delicate and easy to damage
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Three ways that scientists use to investigate the brain
-They study patients with brain damage (by seeing where damage is, they can link place to function)
-Electrically stimulating different parts of the brain +look at effects on persons behaviour
-MRI scanning techniques (see which parts are most active duri
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What is the eye?
The eye is a sense organ containing receptors sensitive to light intensity and colour.
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Name seven parts of the eye
• retina
• optic nerve
• sclera
• cornea
• iris
• ciliary muscles
• suspensory ligaments
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Cornea function
Transparent front of the eye
To start the focussing of the light rays
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Lens function
To focus the light rays onto the back of the eye
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Retina function
Back of the eye
Contains receptor cells for light which allow us to detect light intensity and light colour
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How does the eye detect light?
Light rays pass through the cornea. They then pass through pupil and then through the lens, which focuses the light rays onto back of the eye (retina) Receptor cells in retina send electrical impulses down optic nerve to brain
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Sclera function
White part of the eye
Tough outer structure which protects the eye
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Optic nerve function
Carries electrical impulses from the eye to the brain so an image can be visualised
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Iris and pupil function
Iris is the coloured part of the eye
Pupil is the space in centre of iris which light passes through.
Iris controls the size of the pupil
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How does the iris control the size of the pupil in dim areas?
Light is low so drop in light intensity is detected by light receptors in retina and these send electrical impulses to the brain. The brain then sends electrical impulses to specific muscles in the iris. Theses muscles contract to make pupil larger
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What is accommodation?
The process of changing the shape of the lens to focus on near or distant objects.
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Ciliary muscles and suspension ligaments function
They work with the lens. Together they allow us to focus on distant or near objects

ciliary muscle - circular muscle surrounding lens
suspension ligaments - fibres which connect ciliary muscle and lens
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What does the ciliary muscle do the lens and how?
By contracting or relaxing, the ciliary muscle changes the thickness of the lens
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Light from _____ objects need to only be focused by a relatively small amount
Light from DISTANT objects need to only be focused by a relatively small amount
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How does the eye focus on a near object?
• the ciliary muscles contract so they have a smaller diameter
• the suspensory ligaments loosen
• the lens becomes thicker and refracts light rays more strongly and focuses them on the retina.
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How does the eye focus on a distant object?
• the ciliary muscles relax so has a larger diameter/
• the suspensory ligaments are pulled tight
• the lens is then pulled thin and only slightly refracts light rays.
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What causes short sightedness (myopia) and long sightedness (hyperopia)?
Rays of light do not focus on the retina.
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What causes hyperopia?
They cannot focus on nearby objects.
They eyeball is too short, so the light is focused behind the retina
OR the lens becomes less elastic so the lens cannot become thick enough to focus on near objects
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How can longsightedness be treated?
Glasses with convex lenses which cause light rays to refract more and focus the light rays on retina

Hard and soft contact lenses can also be used (do the same thing as glasses)
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What causes myopia?
They cannot focus on distant objects.
They eyeball is too long, so the light is focused at a point in front of the retina
OR if the lens is too thick
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How can shortsightedness be treated?
Glasses with concave lenses which partially unfocus the light before it enters the eye

Hard and soft contact lenses can also be used (do the same thing as glasses)
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What new technologies are there to treat short and longsightedness?
Laser surgery (change shape of cornea to refract light to a greater/lesser extent)

Replacement artificial lens

Hard and soft contact lenses
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Risks of lens replacement
-Retinal damage
-Cataracts
-Infections
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Other cards in this set

Card 2

Front

The brain is made of billions of interconnected _______ and it has different regions which carry out different _________

Back

The brain is made of billions of interconnected NEURONES and it has different regions which carry out different FUNCTIONS

Card 3

Front

Name three parts of the brain

Back

Preview of the front of card 3

Card 4

Front

Cerebral cortex - where and function?

Back

Preview of the front of card 4

Card 5

Front

Cerebellum - where and function?

Back

Preview of the front of card 5
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