The peripheral nervous system is divided into two main types of nerves: the somatic nervous system (SNS) and the autonomic nervous system (ANS).
Peripheral Nervous System: Two Main Divisions
The peripheral nervous system (PNS) connects the central nervous system (CNS), which includes the brain and spinal cord, to the rest of the body. It's responsible for relaying information between the CNS and organs, limbs, and skin. This intricate system is divided into two main branches based on function:
1. Somatic Nervous System (SNS)
The somatic nervous system (SNS) is responsible for controlling voluntary muscle movements. It allows you to consciously move your limbs, face, and other parts of your body. In addition to muscle control, the SNS also relays sensory information from your eyes, ears, and skin to the central nervous system. This means that when you see a bird, hear a sound, or feel a breeze on your skin, it’s the SNS that's carrying these signals to your brain.
- Key Functions of the SNS:
- Voluntary Muscle Control: Initiates and controls movements of skeletal muscles, allowing actions like walking, writing, and talking.
- Sensory Input: Receives sensory information from the external environment via receptors in the skin, eyes, and ears, and transmits it to the CNS.
- Example: Deciding to reach for a glass of water and feeling its coldness are both functions of the SNS.
2. Autonomic Nervous System (ANS)
The autonomic nervous system (ANS) controls the involuntary functions of your body. This includes activities that you don't consciously think about, such as heart rate, digestion, breathing, and gland regulation. The ANS operates automatically, maintaining internal stability without your direct command.
- Key Functions of the ANS:
- Involuntary Bodily Functions: Regulates essential processes such as heart rate, blood pressure, respiration, digestion, and body temperature.
- Gland Control: Governs the activity of various glands in the body, impacting hormone release and other secretory functions.
- Example: The increase in your heart rate when you exercise or the release of digestive juices after eating are controlled by the ANS.
Summary Table
| System | Function | Type of Control | Examples |
|---|---|---|---|
| Somatic Nervous System | Muscle movement & sensory information relay | Voluntary | Walking, feeling the texture of a cloth, hearing a sound |
| Autonomic Nervous System | Controls involuntary body functions & regulates glands | Involuntary | Heart beating, digestion, sweating, pupillary dilation |
In essence, while the SNS allows for conscious interaction with the external environment through movement and sensory input, the ANS keeps our internal processes running smoothly without our direct involvement. Both are vital components of the peripheral nervous system.
