The central nervous system (CNS) mainly controls actions by sending and receiving messages to various parts of the body.
The CNS, consisting of the brain and spinal cord, acts as the body's control center. Here's a detailed breakdown of how it operates:
How the Central Nervous System Controls Actions
The brain and the rest of the CNS are constantly engaged in a dynamic two-way communication system:
1. Message Transmission
- Instructions from the brain: The brain formulates commands for actions, from simple reflexes to complex movements. These instructions are transmitted as electrical currents, also known as nerve impulses, along nerve fibers called axons.
- Axons as messengers: Axons are like high-speed electrical wires that carry these messages to their target destinations in the body, such as muscles or glands.
2. Receiving Feedback
- Sensory input: The CNS receives feedback from the body via the senses. This includes information about touch, sight, smell, hearing, and internal body conditions.
- Adjustments and responses: Based on this feedback, the CNS can adjust ongoing actions and coordinate new responses to ensure the body is reacting appropriately to its environment.
3. Communication Loop
| Process | Description |
|---|---|
| Brain sends | Instructions to the body for actions via nerve impulses. |
| Axons transmit | The nerve impulses as electrical currents to muscles and other body parts. |
| Senses provide | Feedback to the brain on the state of the body and its environment. |
| Brain adjusts | Adjusts ongoing actions and coordinates responses based on received sensory information. |
Practical Example
For example, when you decide to pick up a cup, your brain sends electrical signals down your spinal cord and to the muscles in your arm and hand. As you reach for the cup, your eyes provide feedback to your brain about the cup’s position. The brain then makes adjustments to ensure your hand smoothly reaches and grasps it. This continuous feedback loop is essential for precise and coordinated movement.
