Control and Coordination
The brain
Learn what each part of the brain does.
The brain and the spinal cord form the central nervous system. The nerves running from them to every part of the body form the peripheral nervous system. The spinal cord is not the backbone: the backbone is like the body of a pen, and the spinal cord is the refill protected inside it.
"Can you tell your heart to stop beating?" No. Some actions you choose (voluntary: writing, walking). Others happen without your choice (involuntary: heartbeat, breathing, digestion).
The brain has three main parts:
| Part | Main jobs |
|---|---|
| Fore-brain | thinking; receiving messages from the senses (sight, hearing, smell); voluntary movement; feeling hungry or full |
| Mid-brain | involuntary actions |
| Hind-brain: medulla | involuntary actions: blood pressure, salivation, vomiting |
| Hind-brain: cerebellum | posture, balance, and making voluntary movements precise (walking in a straight line, picking up a pencil) |
A quick check in a question: "Can I control this myself?" If not, think of the mid-brain or hind-brain. And remember: cerebellum is for balance.
The brain is precious, so it is well protected. It sits inside the hard skull, in a fluid-filled balloon that cushions it from shocks. The spinal cord is protected by the vertebral column (backbone).
"How do muscles actually move?" Muscle cells contain special proteins. When a nerve impulse arrives, these proteins change their shape and arrangement, and the cell shortens. That pulls on the bone and the part moves.
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