Brain and eye

Created by

lilly washington

Cards (39)

The brain is an organ made of billions of interconnected neurones.
What is the function of the brain? 
To coordinate and control complex behaviour
What does the cerebral cortex do?
It controls;

Memory
Intelligence
Language
Consciousness
What does the medulla do ? 
Control sub-conscious activities (e.g heart rate)
What does the cerebellum do ? 
Coordinate muscle activity
The first evidence for different parts of the brain having specific roles came from studying people who have sufficient damage to the brain
Who is Phineas Gage? 
He showed specific areas of the brain were reposnsible for specific functions
What is Electrical stimulation? 
Involves passing an electric current through different regions of the brain and studying the activity. A small electrode is inserted inot the brain tissue or attached at the scalp.
What are the risks of electrical stimulation? 
Damage to delicate brain tissue
Stimulating wrong areas of the brain
What is magnetic resonance imaging (MRI)
It uses magnetic fields and radio waves to build up a detailed picture of the brain. It is non-invasive and doesn't use ionising radiation
What is a functional MRI scan? 
Measures blood flow whilst carrying out a particular activity. Visual image of which parts of the brain are active is created
The eye is a sense organ containing recpetor cells sesnsitive to light
What does the retina do? 
Contains light sensitive receptor cells
What does the optic nerve do ? 
Carries electrical impulses from the retina to the brain
What does the sclera do? 
It is the tough outer layer that protects the eye
What is the cornea? 
Transparent section of the sclera to allow light through
What does the pupil do?
Hole at the centre of the eye to allow light in
What does the iris do? 
Controls the size of the pupil in response to light
What does the lens do? 
Focuses light on the retina to create an image
What do the suspensory ligaments and ciliary muscles do? 
Change the shape of the lens to focus light on the retina
What is adaption? 
Process by which the iris changes the size of the pupil in response to light
In dim light the body needs to maximise the amount of light entering the eye. In bright light the body needs to minimise the amount entering the eye to prevent damage
What muscles control adaptation? 
Radial muscles and circular muscles
What is the response to dim light?
The pupil dilates
Radial muscles contract
Circular muscles relax
What is the response to bright light?
The pupil constricts
Radial muscles relax
Circular muscles contract
What is accommodation? 
Process by which the lens changes shape to view near and distant object
what is refraction? 
When light travels through different speeds or densities, it changes speed which causes it to change direction
Changing the thickness of the lens changes how the light entering the eye is refracted meaning the light can be focused on the retina
What happens with seeing distant objects?
Light rays from distant objects are almost parallel when they enter the eye
Suspensory ligaments - Pulled taut, get shorter
Ciliary muscles - Relax, get longer
What happens to the lens when seeing distant objects? 
It becomes longer and thinner
What happens to the lens when seeing near objects? 
It gets shorter and fatter
What happens with seeing near objects?
Light rays from near objects are spreading out when they enter the eye so need to be refracted more.
Suspensory ligaments - loosen, get longer
Ciliary muscles - Contract, get shorter
What is myopia? 
Short sightedness because light focuses before the retina
What are causes for myopia?
Eye ball too long
lens is too strong
Cornea is too curved
How to treat myopia? 
A concave (diverging lens)
What is hyperopia? 
Long sightedness because the light focuses behind the retina
What are causes for hyperopia? 
Eyeball is too short
Lens is too weak
Cornea is not curved enough
How to treat hyperopia? 
A convex (converging lens)
What are other methods of correcting vision?
Contact lenses
Laser eye surgery
Artificial lens