The Human Brain
The brain is a soft, spongy mass of tissue. It is protected by:
- The bones of the skull
- Three thin layers of tissue (meninges)
- Watery fluid (cerebrospinal fluid) that flows through spaces between the meninges and through spaces (ventricles) within the brain
This picture shows the brain and nearby structures. (Image courtesy of the National Cancer Institute)
The brain directs the things we choose to do (like walking and talking) and the things our body does without thinking (like breathing). The brain is also in charge of our senses (sight, hearing, touch, taste, and smell), memory, emotions, and personality.
A network of nerves carries messages back and forth between the brain and the rest of the body. Some nerves go directly from the brain to the eyes, ears, and other parts of the head. Other nerves run through the spinal cord to connect the brain with the other parts of the body.
The three major parts of the brain control different activities:
- Cerebrum: The cerebrum uses information from our senses to tell us what is going on around us and tells our body how to respond. It controls reading, thinking, learning, speech, and emotions.
The cerebrum is divided into the left and right cerebral hemispheres. The right hemisphere controls the muscles on the left side of the body. The left hemisphere controls the muscles on the right side of the body.
- Cerebellum: The cerebellum controls balance for walking and standing, and other complex actions.
- Brain stem: The brain stem connects the brain with the spinal cord. It controls breathing, body temperature, blood pressure, and other basic body functions.
This picture shows the major parts of the brain.(Image courtesy of the National Cancer Institute)