The Eye + Brain Flashcards
What is the Sclera
It is the fibrous outer structure of the eye, used to protect the eye and provide attachment surfaces for the muscles
What is the cornea
It is a thin transparent layer that covers the front of the eye.
It’s curved shape helps converge the light rays that enter the eye and focus them on the retina
What is the iris
It is a transparent and flexible biconvex lens behind the cornea which focuses light clearly onto the retina
What is the pupil
A hole in the middle of the iris where the light is allowed or continue its passage to the eye
What is the aqueous humour
The aqueous humour is a transparent liquid that plays an essential role in the health of your eye
What is the optic nerve
The optic nerve is the largest sensory nerve of the eye, it carries impulses for sight from the retina to the brain
What is the retina
A layer of sensory neurones, the key structures bring photoreceptors (rods and cone cells) which respond to light
What do cones detect
Colour, and they do not work well in dim light
rod cells detect
Light intensity, and work well in dim light
What is the choroid
It is a pigmented layer of tissue lining the inside of the sclera that prevents the reflection of light rays inside the eyeball
What is the lens
The lens is a transparent bio convex lens that focuses light clearly onto the retina
How are images formed in our brain
1) the cornea refracts light, providing most of the focus to the incoming light
2) the light passes through the pupil and is further refracted by the lens
3) this creates an image on the retina
4) photoreceptors in the retina produce a nervous impulse when exposed to light.
5) the impulse travels down the optic nerve to the brain, which interprets the impulses as a visual image
How to focus on close things
The ciliary muscle contracts, and the suspensory muscles loosen, making the lens more convex (fat). This means that more light is refracted helping you focus well on close objects
How to focus on far objects
The ciliary muscle relaxes, and the suspensory muscles contract, making the lens less convex (thinner). This means that less light is refracted helping you focus on farther objects but not as clearly as close ones
What is shortsightedness
- you can see close objects easily but not far objects
Caused by eyeball being too long or lens being too strong
What is longsightedness
- you can see objects far away but not objects close
Caused by lens being too weak or eyeball being too short
What is the choroid
The choroid is a tissue layer between the sclera and retina that contains blood vessels supplying oxygen and nutrients to the eye.
What is the cerebrum
The largest part of the brain, made of the cerebral cortex, and controls complex behaviours such as learning, memory, personality, and consciousness
What is the cerebellum
Part of the brain which controls posture, balance, and involuntary movements
What is the medulla
Part of the brain which controls automatic actions such as heart rate and breathing
What is the hypothalamus
Part of the brain which regulates temperature and water balance
What is the pituitary gland
The part of the brain that stores and releases hormones that regulate many bodily functions
What is the hypothalamus
The part of the brain which regulates temperature and water balance
What is the Broca’s area
This area of the brain acts as a command center, orchestrating the complex muscle movements necessary for articulating spoken words.
What type of lens can be used to fix longsightedness
Convex lens
What type of lens is used to fix short sightedness
Concave lens
Why does a concave lens help treat short sightedness
Diverges the light rays (pushes the light rays together) to then focus them on the retina
How do convex lenses help treat long sightedness
Causes light to converge (push together) to focus on the retina
What part kf the eye does light pass through first
Cornea
What happens when there is low light levels
-> Pupil of the eye dialates
-> radial muscles contract
-> allows more light to enter the eye
Why is it hard to see when your retina is damaged
Affects retina which mesns light and colour receptors are also damaged
What are cones and rods
Specialised cells in the retina
What do cone cells detect
Colour
What do rod cells detect
Respond to Light levels
