This blog entry
is about one of the most fascinating subjects in biology, the human
brain. The supreme organ in the human body, the brain is what makes
you, you. In the S6EN class we talked about the different functions
of the brain and gave the example of a person cycling. A cyclist will
be using various functions of the brain, and these are the things we
listed in class:
- the beating of the heart
- physical movement
- thinking
- breathing
- sweating
- digesting
- reading
- perception
As you can see
your brain has multiple and vital functions. Some of them are ordered
by you and others are done without you even noticing. For each
different function your brain has an area that deals with that
specific job. For example what part of your brain are you using to
read this right now? Well in fact it is not just one specific part
but multiple parts of the brain that help you see, read and
understand what I'm writing.
This brings us
to what we did next. We were given a diagram similar to this one so
that we would be more familiar with the names, functions and
placement of things in the brain.
This helped us
with the exercise we were given next. These are PET (positron
emission tomography) images
of the brain doing different activities. Using our knowledge of the
brain, based on the diagram above, we were able to identify
the activity in question.
One of the
other things we talked about was the nervous system, although we
didn't go into much detail. We learned that the nervous system is
made up of two main groups, one called CNS (central nervous system)
which includes the brain
and the spinal
cord, amd the other one called PNS (periphiral nervous system)
which is made
up of the nerves around the body.
Dissection
of a brain
In this
experiment, we dissected a calf's brain.
We started by placing the brain in the tray. Then, with the available
tools, we explored the different parts of the brain and tried to
label them. I cut through a lot of parts in the brain to see the
internal structure and I found out that they all had a similar
structure on the inside. The brain was softer than I thought and it
made it harder for me to handle. The dissection helped me understand
how things were placed and at the same time helped memorize the
different functions of specific areas in the brain.
the
materials we used in this experiment were the following:
- a tray
- a straight needle
- scissors
- a scalpel
- gloves
- a lab coat
I
positioned the brain in a way that allowed me to see the superior
part of it. Although the two hemispheres detached from each other the
moment I put the brain on my tray, the cerebellum was still firmily
attached. This in a way made it easier for me to observe the two
sides of the brain seperatly. The corpus callosum is the white stuff
that holds the two sides of the brain together but in my case it was
cut. The brain is filled with crevasses. The actual crevasse is
called sulcus and the space between them is called gyrus.
Then
cut open the cerebellum to examine the insides and saw the white and
gray matter.
I
also cut the medulla open which was tougher and saw the beginning of
the spinal cord. The picture also shows the pons on the right bottom
corner.
I
took the left side of the brain and cut it open and saw the same two
kinds of matter that were in the cerebellum, the white and gray
matter.
I
observed and labelled different parts in the brain all throughout the
dissection. I noticed how flexible and fragile the brain was at some
parts. This made it harder for me to handle and when I cut one of the
hemispheres of the brain open, the white matter seemed to almost fall
out completely because of how soft it was. This is why the brain has
maximum protection around it, like the skull, the cerebrospinal fluid
that surrounds the brain to cushion it, and a series of membranes the
first one being dura mater which acts as a kind of seatbelt.
Obviously these were not on the brain when they were given to us
otherwise it would have being a lot harder to cut through it. When
cutting through different parts of the brain I realised that they
were all composed of the same thing, grey and white matter. The white
matter serves as a sort of insulator in order to keep the current
flowing through the grey matter which is full of nerves. This helps
avoid any chemical and electrical signals from neurons to move
randomly, and ensures they reach the correct destination. I
also learned that the reason why the brain has many folds (filled
with veins) is to take less space and fit inside our skull.
What
made this experiment difficult was labelling the different parts of
the brain since there was no line telling you when it started and
when it ended. I also never found the hippocampus.
The
brain of a calf is very similar to that of a human and so gives us a
clear idea of what our brain looks like. It also helps us understand
how the parts fit in a 3D space rather than looking at it on a flat
piece of paper. After this dissection I am even more fascinated about
the brain and the functions it performs. The brain is one of the most
amazing organs, it keeps our heart beating without conscious effort
and is parallel processing all the time. The brain is a highly
complex organ that remains an object of scientific study.
References:
http://www.austincc.edu/apreview/PhysiologicalSystem/Nervous.html
http://www.dreamlanguage.org/articles/cognitive_function_in_dreams.htm
