In this lesson today, we dissected a cow’s eye. In the experiment, we used dissecting scissors and tweezers.
In the experiment, we had to follow a series of steps to complete the dissection. Step one was to identify the optic nerve (which sends the information to the brain that the eye sees) and cornea (Which is just a protective layer around the eye), and to cut away the fat around the eye to locate them, which was quite tough. The next step was to cut around the middle of the eye to open it. We also had to be careful not to cut into the cornea. Step 3 was to identify the retina (which was attached to the optic nerve) and the vitreous humor. Then we had to pull the humerus, which was the clear, jelly-like substance, out of the eye. Step 4 was to identify and pull out the lens, which, if you look into it, acts like a magnifying glass. Step 5 was to identify the pupil, which has a hole in the middle that makes it look like a donut, and remove it. Then we identified the iris. After that, we had to remove the iris and the ciliary body, which is another black substance attached to the iris, from the cornea.
Three parts of the eye: what they do:
Lens:
The Lens is an almost clear, pebble-shaped, cushy structure inside the eye that focuses light onto the retina so we can see a sharp image. It changes shape to help us see things clearly at different distances, becoming thicker/bigger in size to focus on close objects. The lens works together with the cornea, but it does the fine-tuning of focus, a bit like adjusting the focus on a camera, so the picture is not so blurry.
Optic Nerve:
The Optic Nerve is like the eye’s information cable at the top of the brain. It carries messages made from light hitting the retina at the back of the eye. These messages travel along the optic nerve to the brain, which then turns them into the images we see. Without the optic nerve, the eye could still collect light, but the brain wouldn’t be able to understand what the eye is seeing.
Iris:
The Iris is the coloured ring of muscle around the pupil that controls how much light enters the eye. When it’s bright, the iris makes the pupil smaller to let less light in, and when it’s dark, it makes the pupil bigger to let more light in. This helps protect the eye from to much light and also makes sure we can still see in dim light.
Though in this experiment I did little amount of work as I couldn’t stand the texture or smell of the eye, though I observed it carefully throughout the lesson.