THE HUMAN BRAIN
The human body is divided into many different parts called organs. All of the parts are controlled by an organ called the brain, which is located in the head. The brain weighs about 2.75 pounds, and has a whitish-pink appearance. The brain is made up of many cells, and is the control center of the body. The brain flashes messages out to all the other parts of the body. The messages travel in very fine threads called nerves. The nerves and the brain make up a system somewhat like telephone poles carrying wires across the city. This is called the nervous system. The nerves in the body don’t just send messages from the brain to the organs, but also send messages from the eyes, ears, skin and other organs back to your brain. Some nerves are linked directly to the brain. Others have to reach the brain through a sort of power line down the back, called the spinal cord. The brain and spinal cord make up the central nervous system. The brain doesn’t just control your organs, but also can think and remember. That part of the brain is called the mind.
Twenty-eight bones make up the skull. Eight of these bones are interlocking plates. These plates form the cranium. The cranium provides maximum protection with minimum weight, the ideal combination. The other twenty bones make up the face, jaw and other parts of the skull. Another way the brain keeps it self safe is by keeping itself in liquid. Nearly one fifth of the blood pumped by the heart is sent to the brain. The brain then sends the blood through an intricate network of blood vessels to where the blood is needed. Specialized blood vessels called choroid plexuses produce a protective cerebrospinal fluid. This fluid is what the brain literally floats in. A third protective measure taken by the brain is called the blood brain barrier. This barrier consists of a network of unique capillaries. These capillaries are filters for harmful chemicals carried by the blood, but do allow oxygen, water and glucose to enter the brain.
The brain is divided into three main sections. The area at the front of the brain is the largest. Most of it is known as the cerebrum. It controls all of the movements that you have to think about, thought and memory. The cerebrum is split in two different sections, the right half and the left half. The outer layer of the cerebrum is called the cortex. It is mainly made up of cell bodies of neurons called grey matter. Most of the work the brain does is done in the cortex. It is very wrinkled and has many folds. The wrinkles and folds give the cortex a large surface area, even though it is squeezed up to fit in the skull. The extra surface area gives the cerebrum more area to work. Inside the cortex, the cerebrum is largely made up of white matter. White matter is tissue made only of nerve fibres. The middle region is deep inside the brain. It’s chief purpose is to connect the front and the back of the brain together. The back area of the brain is divided into three different parts. The cerebellum sees to it that all the parts of your body work as a team. It also makes sure you keep your balance. The thalamus is located in between above the lower brain and under the two hemispheres.
THE DIFFERENT SECTIONS OF THE BRAIN: Most of the above mentioned parts of the brain were produced early in evolution but the higher mammals, especially humans went on to produce a sort of thinking cap on top of these parts. This thinking cap was divided into two different parts, the left hemisphere and the right hemisphere. If the left side of your brain is more developed like most people’s are, you are right handed. On the other hand if the right side of your brain is more developed, then you will be left handed. The right side of your brain is more artistic and emotional while the left side of your brain is your common sense and practical side, such as figuring out math and logic problems.
THE CEREBELLUM: One of the most important parts of the human brain is the cerebellum. The cerebellum is involved with the more complex functions of the brain and sometimes is even referred to as the brain within the brain. The cerebellum acts as a control and coordination center for movement. The cerebellum carries small programs that have been previously learned. For example, how to write, move, run and jump are all previously learned activities that the brain recorded and can playback when needed. Every time you practice, the brain rewrites the program and makes it better. You may have heard the saying practice makes perfect. Well this saying is not entirely true; another way of practicing is just to imagine what you wish to do. Since the cerebellum can’t actually feel, it will think that you are doing what your imagining and respond by rewriting it’s previous program and carrying out any other actions needed for that function.
THE CEREBRAL CORTEX: The cerebral cortex makes up the top of the two hemispheres of the brain. The cortex is a sheet of greyish matter which produces our thoughts, language and plans. It also controls our sensations and voluntary movements, stores our memories and gives us the ability to imagine, in short it’s what makes humans, humans.
The Internet, various sites.
Microsoft Encarta Encyclopedia 1998 edition
Britannica by Britannica, Encyclopedia Inc.copyright Encyclopedia Britannica Inc., 19864.