Title: The Human Eye LO: 1. Identify the parts of the human eye and state their functions. 3/4/2019 STARTER: What do these have in common?

A journey through the human eye.

CORNEA (clear lens in front of eye) transparent covering of the front of the eye Allows for the passage of light into the eye and functions as a fixed lens.

allows for the passage of light into the eye and it also focuses the light

Pupil size is controlled by iris muscles PUPIL (black hole) black hole in iris where light enters

the hole where light enters into the eye

THE EYE: PUPIL When the eye needs more light to enter (when it is dark), the pupils get larger; allowing more light to enter the eye

THE EYE: PUPIL When the eye needs less light to enter (when it is very bright), the pupils get smaller; allowing less light to enter the eye

The iris is a colored, circular muscle IRIS (colored part) colored part of eye controls light entering

controls the amount of light entering the eye

SCLERA – a tough white skin (made of tissue) that covers all of the eyeball except the cornea. SCLERA (white part) whites of the eye supports eyeball provides attachment for muscles

supports eyeball and provides attachment for muscles

LENS (lens behind pupil) converging lens allows us to see objects near and far

RETINA internal membrane contains light-receptive cells (rods and cones) converts light to electrical signals

converts light waves to electrical signals

OPTIC NERVE Transmits electrical impulses from retina to the brain Creates blind spot Brain takes inverted image and flips it so we can see

Transmits electrical signals from retina to the brain

Your 2 Lenses: Cornea and Lens There are two lenses in your eye, the cornea and the lens. The cornea, the front surface of the eye, does most of the focusing in your eye The lens provides adjustable fine-tuning of the focus

The light is refracted as it passes through the lenses in our eyes. Our eyes are equipped with convex lenses. These lenses focus the light and enable us to see. The point where the rays cross is called the focus or the focal point.

Yes, the picture that your eye takes is upside down too!

Well, your eye sends the picture to your brain, and your brain turns the picture the right way up and tells you what you are looking at. So you see things the right way up.

Structure of Eye

TASK: Draw lines matching the number with the name, and name with the function of each structure of the eye. 1Retina transparent outer part of your eye 2Pupil focuses light entering the eye 3Sclera changes size to adjust the amount of light 4Iris a muscle that controls the size of the pupil 5 Optic nerve sends electrical impulses from eye to the brain 6Cornea Photosensitive layer of cells at the back of the eye 7Lens Hard structure forming the outside of the eye

TASK: Draw lines matching the number with the name, and name with the function of each structure of the eye. 1Retina transparent outer part of your eye 2Pupil focuses light entering the eye 3Sclera changes size to adjust the amount of light 4Iris a muscles that controls the size of the pupil 5 Optic nerve sends electrical impulses from eye to the brain 6 Cornea Photosensitive layer of cells at the back of the eye 7Lens Hard structure forming the outside of the eye

TASK: Complete the diagram showing how the two rays will look like after passing through the convex lens. Label the focal point. Focal point

TASK: Arrange the structures of the eye in the correct order (as light travels through the eye). Retina Brain Lens Pupil Optic nerve Cornea Pupil Lens Retina Optic nerve Brain

Plenary 1. Which part of a eye a. Focuses light b. Detects light 2. Name the primary colours of light. 3. Name two types of cells in retina.

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