The Nervous System- The Eye Flashcards
What does the optic nerve do?
It carries impulses from the receptors to the brain
What does the lens do?
It refracts light, focusing it onto the retina
What does the sclera do?
It protects the eye
What does the retina contain?
The retina contains light receptors and it’s where the light focuses. The receptors are called rods and cones
Explain the what happens when light rays pass thought the pupil
When light rays pass through the pupil, the Ray is focused by the lens onto the retina when receptors send impulses along the optic nerve to the brain
What is the function of the ciliary muscle?
It contracts and relaxes to change the shape of the lens
What does the iris do?
The iris is the coloured part of the eye. The iris controls the size of the pupil and it also controls how much light enters the eye
What does the dispensary ligaments do?
Hold the lens in place
What does the cornea do?
It focuses light at the back of the eye and it refracts the rays of light
What does the pupil do?
The pupil is the hole which light passes. It is controlled by the iris otherwise it will get damaged. When a lot of light passes, it gets smaller and then less light if passing it gets bigger
What are rods?
Rods are more sensitive in dim light but can’t sense colour
What are cones?
Cones are sensitive to different colours but are not so good in dim light e.g red- green colour blindness
Explain what happens to the ciliary muscle when an object is near
It contracts
Explain what happens to the ciliary muscle when an object is distant
It relaxes
Explain what happens to the suspensory ligaments when an object is near
It’s slackened
Explain what happens to the suspensory ligaments when an object is distant
It’s stretched
Explain what happens to the muscle tension on lenses when an object is near
The tension in low
Explain what happens to the muscle tension in lenses when an object is distant
It’s high
Explain what happens to the lens shape when an object is near
It’s fat
Explain what happens to the lens shape when an object is distant
It’s thin
Explain long sighted
When someone cannot focus on near objects. The lens is the wrong shape and doesn’t bend the light enough or the eyeball is too short. The images of near objects are brought into focus behind the retina. Convex lens can be used to correct it
Explain short sighted
When people are unable to focus on distant objects. When lens is the wrong shape and bends the light too much or the eyeball is too long. The images of distant objects are brought into focus in front of the retina m. Concave lens can be used to correct this, alternatively a corneal laser surgery is an option as well.
What is binocular vision and what are some of its advantages?
Binocular vision is when both eyes are at the front of the head and they work together. When looking at an object, the brain compares the image seen by each eye. This allows us to judge distance well, but gives us a narrow field of vision
What is monocular vision and what are some of its advantages?
Monocular vision is when each eye is at the side of the head and this allows the organism to have a wider field of view
Name nine parts of the eye
- Suspensory Ligaments
- Cornea
- Pupil
- Iris
- Ciliary Muscle
- Lens
- Optic Nerve
- Retina
- Sclera
