Brain is one of the largest and complex organs in the human body and weighs about 1.3 Kgs. Neurons and glial cells are the basic units that make up the brain. There are about 40 billion nerve cells, known as neurons, in the brain. Brain controls our body, receives, analyzes and stores information. It produces electrical signals, which, together with chemical reactions, helps in the communication of the different parts of the body. The brain has three main parts: the cerebrum, the cerebellum, and the brain stem (medulla).
Blood vessels (arteries, capillaries, and veins) supply the brain with oxygen and nourishment, and remove waste products. The cranium (the top of the skull) surrounds and protects the brain. Cerebrospinal fluid (CSF) is a clear, watery liquid that surrounds the brain and cushions it from jolts.
The neurons in the brain divide rapidly till about 7 years of age. Further development is by the existing cells making increasingly elaborate connections with each other. When this control is lost in a single cell, then it starts dividing in an uncontrolled manner. As the cell makes more and more copies of itself, it grows to form a tumor. A brain cancer can arise from any of the cells, which makes up the brain.