Sunday, January 25, 2015

Pig Eye Dissection - Dissecting with Children

We dissected pig eyes.

Biology with laboratory is a subject that can be intimidating to many home educators. Some parents don't feel confident in their own knowledge of the subject, and others aren't excited over figuring out where/how to secure the materials. Fortunately, the most important part for kids is the opportunity to explore. A textbook, library book on the subject or videos such as these can be the teacher. That just leaves supplying the dissecting materials for the parents.


Eyes


Human eyes are similar to the eyes of other mammals, but there are some differences. They all have optic nerves in the back which connect to the brain and muscles surrounding the eye which work to alter the shape of the lens for focusing and moving the eye within the socket. The white part of the eye, known as the sclera, is not visible on most mammals, but is clearly visible on humans.

Rods and cones are the photoreceptor part of the central nervous system located in the back of the eye. Humans have around 120 million rods which are very sensitive to light, but only about 6.5 million cones which are sensitive to color. Most fish and underwater reptiles have no cones, thereby making them colorblind.

Eyes don't grow or change size with age. Instead, the muscles surrounding the eyes change creating the illusion that the eyes grow. Most mammals have only four ocular muscles surrounding the eye, but primates have six which allows them to roll their eyes.

 
Filling a plastic bag with water acts like a magnifying glass and the lens of the eye. The lens actually looks just like a sack filled with water, only it's much smaller.

An important prerequisite to dissecting is preparing a dinner which contains meat. This is very important for cutting skills.

The pig eyes were obtained from a local butcher and since they were fresh, they did not have a strong smell.

Dissection of the pig eye was accomplished in only about four steps.
1. The excess fat and skin was cut off.


2. The cornea was punctured to drain the aqueous humor.

 
3. The sclera was punctured and then cut around the perimeter to create two halves of the eye.

4. Once the eye was separated into the two halves, the iris, cornea and lens were pulled out and inspected.

The kids found the vitrious and aqueous humor within the eye had the consistency of egg white.


Really - it wasn't gross. Several kids couldn't wait to get at the eyeballs. Handling them wasn't much different than handling uncooked meat to be prepared for supper.

 He has three eyes!


To see more of our biology unit study please visit our science page. Also on the science page are several human body science projects geared for younger children which provide a good foundation for this activity.

1 comment:

  1. How fun we just completed dissecting a cow's eye:) Looks like a great size group

    ReplyDelete

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