The nervous system is one of the most important systems in the human body. It helps us think, feel, move, and react. For exams like SSC, RRB NTPC, UPSC, and State-level exams, understanding the Central Nervous System (CNS) and Peripheral Nervous System (PNS) is essential.
Let’s break down the topic into simple parts so you can understand and remember it easily!
What is the Nervous System?
The nervous system is the body’s control center. It sends and receives messages between the brain and the rest of the body.
It has two main parts:
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
Central Nervous System (CNS)
The CNS is the main command center of the body.
◾Parts of the CNS:
🔹 Brain
🔹 Spinal cord
🔺Functions of CNS:
🔹 Controls all body functions
🔹 Receives information from the body and decides how to respond
🔹 Helps us think, learn, and remember
📌 Important Facts:
- The brain is protected by the skull.
- The spinal cord is protected by the vertebral column (backbone).
- The brain has different parts like cerebrum, cerebellum, and medulla oblongata.
Peripheral Nervous System (PNS)
The PNS connects the rest of the body to the CNS. It acts like a messenger system.
◾ Parts of the PNS:
🔹 Nerves that go to and from the CNS
🔹 Includes:
- Cranial Nerves (from the brain)
- Spinal Nerves (from the spinal cord)
🔺 Functions of PNS:
🔹 Sends messages from the body to the CNS
🔹 Carries instructions from the CNS to muscles and organs
🔹 Helps us react quickly to things (like touching something hot!)
Types of Nerves in PNS
| Type of Nerve | Function |
|---|---|
| Sensory Nerves | Carry messages to the brain from senses |
| Motor Nerves | Carry instructions from brain to muscles |
| Mixed Nerves | Do both functions |
Major Differences Between CNS and PNS
| Aspect | Central Nervous System (CNS) | Peripheral Nervous System (PNS) |
|---|---|---|
| Definition | The CNS is the main control center of the body | The PNS connects the CNS to the rest of the body |
| Main Components | Brain and Spinal Cord | Nerves (cranial and spinal) and ganglia |
| Location | Enclosed within the skull and vertebral column | Located outside the skull and vertebral column |
| Function | Processes, interprets, and stores information; controls thoughts and actions | Transmits signals between CNS and the body (muscles, glands, organs) |
| Protection | Protected by bones (skull & vertebrae), meninges, and cerebrospinal fluid (CSF) | Not enclosed in bones; less protection, more vulnerable |
| Type of Neurons | Contains interneurons primarily | Contains sensory and motor neurons |
| Signal Flow | Processes incoming sensory data and sends out motor commands | Sends sensory information to CNS and carries motor commands from CNS |
| Repair/Regeneration Ability | Limited regeneration (especially in the brain) | Some ability to regenerate damaged nerves (especially in axons) |
| Subdivisions | None | Divided into somatic and autonomic nervous systems |
| Examples of Structures | Cerebrum, cerebellum, spinal cord | Spinal nerves, cranial nerves, autonomic nerves |
Why Is This Important for Exams?
Questions from this topic often appear in General Science or Biology sections. Examples:
📝 Sample Questions:
Q1. Which part of the nervous system includes the brain and spinal cord?
A. Central Nervous System ✅
Q2. What is the function of the Peripheral Nervous System?
A. It carries messages between the body and CNS ✅
Q3. Sensory nerves carry messages to which organ?
A. Brain ✅
Easy Way to Remember
🧠 CNS = Central Command (Brain + Spinal cord)
🦾 PNS = Pathway of Nerve Signals (Nerves across the body)
✅ Summary Table
| Nervous System | Includes | Main Function |
|---|---|---|
| CNS | Brain, Spinal Cord | Control center for the body |
| PNS | Nerves (cranial/spinal) | Connects CNS to rest of the body |
Understanding the nervous system is key to scoring well in exams. Don’t worry if it feels complex — just break it into parts, use tables and mnemonics, and revise regularly. Remember:
Quick Revision Keywords for Exams:
- CNS = Brain + Spinal Cord
- PNS = Nerves (Cranial + Spinal)
- Sensory Nerves = To Brain
- Motor Nerves = From Brain
- CNS = Protected by bones
- PNS = Messenger system
