New
New
Year 10
OCR
Foundation

The human eye

I can describe the main structures of the human eye and their functions.

New
New
Year 10
OCR
Foundation

The human eye

I can describe the main structures of the human eye and their functions.

Lesson details

Key learning points

  1. The human eye is a sense organ that detects light to enables us to see.
  2. The functions of the cornea, iris, lens, ciliary muscles, retina and optic nerve.
  3. Interpretation of ray diagrams showing refraction, to explain how the eye focuses light onto the retina.
  4. The iris expands and contracts (a reflex response) to control the amount of light entering the eye through the pupil.
  5. Use appropriate techniques to investigate the size of the pupil in different light levels.

Common misconception

There is often confusion between parts of the eye and their function, and that both the cornea and the lens refract light, but only the lens can focus light.

The parts of the eye and their function are covered carefully and in detail. The role of the cornea and lens in refracting and focusing light is examined in detail with simplified drawings to demonstrate.

Keywords

  • Lens - An object that can focus light rays. In the eye, it brings light rays to focus on the retina.

  • Refraction - Occurs when light travels from one transparent medium to another, causing a change in direction.

  • Focus - The process of bringing light rays together to converge at a single point creating a clear image.

  • Focal point - The point where rays of light meet after passing through a lens.

  • Reflex response - An involuntary, fast neural response to a situation.

You can use a light box and a convex lens to demonstrate how the eye works, but be careful it doesn't take up too much lesson time. A 3D model of the eye that can be taken apart is also really useful to make it more realistic.
Teacher tip

Equipment

None required.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
What does the eye detect?
chemicals
Correct answer: light
touch
heat
Q2.
True or false? Muscles are effectors.
Correct answer: true
false
Q3.
True or false? The reflex arc is a lengthened neural pathway.
true
Correct answer: false
Q4.
Put the steps of this reflex arc in the correct order.
An image in a quiz
1 - The stimulus is detected by the receptor.
2 - A nerve impulse is sent along the sensory neurone.
3 - In the spinal cord, a relay neurone transfers the impulse to the motor neurone.
4 - This triggers the effector muscle to contract and produce the response.
Q5.
What organ is not initially involved in a reflex response?
Correct Answer: The brain, Brain
Q6.
How can the brain override some reflex responses?
An image in a quiz
By triggering the sensory neurone in the reflex arc.
By triggering the relay neurone in the reflex arc.
Correct answer: By triggering the motor neurone in the reflex arc.

6 Questions

Q1.
Match the part of the eye to its name.
An image in a quiz
Correct Answer:a,cornea

cornea

Correct Answer:b,iris

iris

Correct Answer:c,lens

lens

Correct Answer:d,ciliary muscles

ciliary muscles

Q2.
The ciliary muscles contract or relax to change the shape of the ...
Correct Answer: Lens, lens
Q3.
Which statement correctly describes the lens and ciliary muscles if you are focusing on an object that is far away?
The lens is short and fat in shape beacuse the ciliary muscles contract.
The lens is short and fat in shape because the ciliary muscles relax.
The lens is long and thin in shape because the ciliary muscles contract.
Correct answer: The lens is long and thin in shape because the ciliary muscles relax.
Q4.
Put the following steps in order to describe how we see.
An image in a quiz
1 - Light enters the eye.
2 - Light is refracted by the cornea.
3 - Light is focused by the lens.
4 - Light is sensed by the retina.
Q5.
Which of the following responses happen to the eye in the dark?
Correct answer: circular muscles in the iris relax
circular muscles in the iris contract
radial muscles in the iris relax
Correct answer: radial muscles in the iris contract
Q6.
How can we investigate the effect of light on pupil size?
Lucas: We can shine a bright torch in someones eyes to see the pupil change
Correct answer: Sofia: We can sit in the dark then turn on a light and see how the pupil changes
Sam: We can look at different peoples eyes
Jacob: We can watch someones eyes to see if it changes