Answer: The human brain is the command center for the human body and nervous center. It receives information such as pain and can also output information to different parts of the body such as muscles, or legs and arms. The human brain is structurally similar to other animals but differs in size. The brain controls what we think, remember, and how we move. The brain is the most complex organ in the human body. The brain weighs about 1.4 kilograms and is consists of jelly-like tissue and has about 100 billion nerve cells, or neurons.