Cow Eye Dissection - Hurumanu - Science

In Science, we dissected a cow's eye. The first thing we did was we watched a video of how to dissect it and also the parts of its eyes. 

The person dissected it layer by layer. 

Aim: To dissect a cow's eyes. 

Equipment: 

• Tweezer 
• Dissecting Scissors  
• Newspaper
• Cow's eyes
• Newspaper (We didn't have a tray)

Method: 

1. Remove any excess fat surrounding the eye. After cutting the excess fat, you'll see the optic never at the back of the eye.

2. Puncture the corner of the in-between the cornea and the sclera using the sharp end of the dissecting scissor.

3. After putting a small hole, cut around the cornea. After cutting the cornea, you'll see the parts clearer, you'll see the iris, pupil, lens, ciliary body and the vitreous humour.

4. Separate the iris, pupil and the lens to study and see them better. You'll see little details of each three of them.

5. Squeeze the jelly-like liquid called the vitreous humour.

6. Cut the eye in half to see the tapetum lucidum along with the retina and the choroid. 

Findings: 

Each part was very interesting to look at and to study. I think the cow's eye was fresh because the fat is not hard, it's still a bit soft. It was difficult to puncture the eyes because it's very squishy and it bounces back so we had to cut it on the side instead of puncturing, it let the liquids out. 

Eye structure:

• Cornea – a clear, round window at the eyeball front. It allows light into the eye, protects the eye and bends light rays so images can focus on the retina.
• Iris – the coloured part of the eye with the pupil at the centre. Different coloured irises result from different amounts of the pigment melanin. The iris is a muscle that can adjust the pupil size so light can enter, forming a retinal image.
• Pupil – a dark space in the middle of the iris. It enlarges in low light, allowing light in, and it constricts in bright light, reducing the light entering.
• Lens – found behind the iris inside a clear capsule. It bends light, forming an image on the retina. The cornea bends 70% of incoming light and the lens 30%. Fibres hold the lens in place. Looking closely at an object changes fibre tension, causing the lens shape to change to accommodate the object’s distance.
• Optic nerve – nerve fibres connecting the retina and brain. While retinal cells change sight into electrical impulses, the optic nerve sends them to the brain’s visual cortex. The image is upside down but the brain turns it up the right way.
• Retina – a lining inside the back of the eyeball that contains light-sensitive receptors – rods and cones. It receives light rays from the lens, forming an image. These are changed into electrical signals and sent to the brain.

Conclusions:

I find the experiment interesting because I didn't know what a cow's eye nor a person's eyes looked like internally until we dissected it for the experiment.