The brain is located in the top part of the head called the skull. The skull, which is made up of 28 bones, serves the sole purpose of protecting the brain from injury and trauma.
The brain is made up of many parts, but all of these parts are divided into one of two categories. The right hemisphere and the left hemisphere are the two main parts of the brain. The cells that are in the right part of the brain control the left part of the body; the cells that are in the left part of the brain control the right part of the body. These cells are necessary for function of life, and the brain contains enough cells to last throughout a lifetime.
In order for the brain to survive, it must be constantly receiving oxygen. The longest a brain can go without oxygen is around 3 to 5 minutes. After that time period, irreparable injury will occur to the brain. The brain is a medium-sized organ and is about the size of a grapefruit. It ranges from pink to gray in color. It is made up of soft material and adult brains weigh around 3 pounds while children's brains weigh from about 1 to 2 pounds.