The Sheep Eye Dissection

Yesterday, we completed a sheep dissection in class. The images below represents the different stages of our dissection. The first image shows the cornea, which is the clear layer of proteins covering the main portion of the eye. What is fascinating about the cornea is that these transparent proteins do not require any blood or oxygen as there are no capillaries in the cornea. Also shown in the first image is the sclera, extrinsic muscle, and fatty tissue. The sclera is an EXTREMELY tough (it took a bunch of cuts with our scalpel to finally break through it) which protects and contains the contents of the eye. Onto the next image. As you can see, my partner and I (finally) cut through the sclera. In essence, we opened the eye. On the left half of the eye, we see the jelly-looking substance: the vitreous humor. This jelly helps to maintain the pressure inside of the eye. On the right half, the banana-looking structure is the retina. The retina receive light that the lens has focused, convert the light into neural signals, and send these signals on to the brain for visual recognition. The black and iridescent blue film behind the retina is the choroid. This is used to reflect light. The tapetum lucidum, the iridescent blue portion, is used to help nocturnal animals see in the dark. Humans do not have a tapetum lucidum. In the third and final image, the eye is completely take apart. The vitreous humor, the cornea, the choroid, the tapetum lucidum, and the sclera are visible. Three new pieces are the lens, which is to the right of the vitreous humor and to the left of the cornea, and the pupil and iris, which is between the upturned half of the eye (with the choroid) and the cornea. The iris is the brownish region in the sclera. The pupil is the opening inside the iris. The whole job of the iris and pupil is to control the amount of light that gets into the eye. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a sharp real image of the object of interest to be formed on the retina.

An untouched sheep's eye

A sheep's eye with the back part removed.

From left to right: vitreous humor, lens, cornea, front of eye,
and back of eye

Almost finished!!!

I have learned that I need to persevere and ask for what I want. I have also learned about the continual slowness and not-promptness of schools and replying. Recently my mom came up with the idea to just send one email to 100 or so school principals and special education directors so that I can hopefully get a reply from someone. And I did!!! The Loma Prieta school district finally replied, and I am in the process of setting up a time to meet the coordinator to present about this program! I can apply this to myself because this project is teaching me that I need to make my own path and make myself be heard. 

The Clay Brain

For our clay brain lab, we created two clay diagrams of the brain: one of the left hemisphere along the sagittal plane and one of the right cerebral hemisphere. We showed the major parts of the brain such as the pineal and pituitary gland and the hypothalamus in the right cerebral hemisphere diagram. We showed the many different sulci and gyri of the brain in the left hemisphere along the sagittal plane diagram.

The Woman With a Hole in Her Brain

This article is about a woman who is missing her cerebellum. The cerebellum's function is to control voluntary movements and balance, and it is also thought to be involved in our ability to learn specific motor actions and speak. She lived in oblivion until she was 24 when she had to go to the doctor because she had reported dizziness and trouble walking. Her brain has adapted to function without her cerebellum and she doesn't report too many hindrances. This woman is defying what we already know since she has lived a lot longer than the other 9 people who have lived without a cerebellum. 

Broca's area is linked to speech production. Broca's area is named this after a man named Broca who discovered that patients with aphasia in this region of the brain were able to form cognizant thoughts, but they were not able to put these thoughts into words or write them down. It is possible to live without this region of your brain, though it would be very difficult to communicate with others as they would only be able to think things and not be able to put them into words or writing. Other parts of the brain may be able to take over so that the deficit is not as apparent, but there would still be detrimental effects if Broca's area was removed or severely damaged. Other areas, such as the area of hand movement for signaling will become more fine-tuned so that hand signaling could be used to communicate instead of words.