Cow Eye with answers

					Cow Eye Dissection                                                          Name: __________________________ Per: ______
Can you read this with the lens from your cow eye? How cool is that !

Match the following parts of the eye to their function: (optic nerve, sclera, iris, retina, lens, pupil, vitreous
humor, aqueous humor, choroid, tapetum, ciliary body)

Retina Contains sensory receptors for vision

Iris The colored portion of the eye.

Lens This structure changes shape to focus light on the retina

Pupil The opening in the iris through which light passes

Vitreous Humor Helps the eyeball keep its round shape and prevents it from collapsing

Sclera Outer layer of the eye. Protects the eye and helps it keep its shape

Optic Nerve Cord at the back of the eyeball. Carries impulses from the eye to the brain

Aqueous Humor Fills space between the lens and cornea. Plays a part in focusing light rays

Ciliary Body Consists of muscles, which control and shape the lens.

Tapetum The iridescent portion of the choroid layer in nocturnal animals.

Choroid Dark colored layer underneath the retina. Contains blood vessels which supply nutrients and

                                     oxygen to the eye

          Without looking at any diagrams, think about the structure of the eye. Now imagine some light entering
          the eye. List in order the parts of the eye that the light must pass through until it reaches the back of the
The correct order is:

    Cornea Aqueous Humour Pupil Lens Vitreous Humour Retina

    What parts of the eye are designed to protect the inside of the eye? What properties do these parts have
    that enable them to provide protection?

The sclera has a tough surface that acts as a shell to protect the inside of the eye.

    The fat surrounding the eye is soft and acts as a cushion to absorb shock on the eye.

                                                               Why is the image seen in a myopic (near-
                                                               sighted) eye distorted?

                                                               Image not focused on retina

                                                               Draw how hyperopia (far-sightedness) image
                                                               would form in an eye.

                                                               Focal point would be behind retina

Pink eye, or conjunctivitis, is redness and inflammation of the membranes (conjunctiva) covering the whites
of the eyes and the membranes on the inner part of the eyelids. Why should you NEVER share lab goggles?

Bacteria can easily be transferred between people.

What do you think are the parts of the eye that are the most easily damaged or injured? Explain your answer

You could justify several different answers.
The cornea is soft and found on the front of the eye. It can be scratched easily.
The pupil and iris can all be damaged easily as the cornea doesn’t provide a very tough protective
covering for these structures.

As you observed, the retina connected with the optic nerve at the back of the eye. Why is this connection
essential? What would happen if the retina became disconnected from the optic nerve?

The connection is essential as the retina needs to be able to send its images through the optic nerve
If the retina is disconnected, the brain would not be able to receive the images from the eye.
In humans, the choroid layer (the vascular layer of the containing connective tissue, and lying between the
retina and the sclera) is black. Why do you think this layer is dark in color? What would the effect be if the
layer has a silver or white color instead?

The black layer helps to absorb all the light rays without reflecting any back out of the eye. This will
enable the retina to have a clear and accurate image. A white layer would reflect all light rays, while
a silver layer would reflect most rays.

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