5.7 Main Components of Nervous System

The human nervous system is a complex network of specialized cells that coordinate the body's activities. It consists of two main components: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS acts as the coordinating centre, while the PNS connects the CNS to the rest of the body.

Definition

Nervous System: The system of the body that provides coordination through electric signals among different body parts for the response to a particular stimulus is called the nervous system.

Central Nervous System (CNS): The central nervous system consists of the brain and spinal cord. It is a coordinating centre and lies in the midline of the body.

Peripheral Nervous System (PNS): The peripheral nervous system transmits information from receptors to CNS and transmits orders and commands from CNS to effectors.

Main Idea

• The human nervous system is the most evolved among all animals.
• It consists of two main components:
• The CNS is a coordinating centre and lies in the midline of the body.
• The PNS transmits information from receptors to CNS and transmits orders and commands from CNS to effectors.

Core Concept

• Nervous system = provides coordination through electric signals
• CNS = brain and spinal cord
• PNS = nerves that connect CNS to the rest of the body
• **CNS** = coordinating centre
• PNS = transmits information and commands
• Neurology = study of the structure and functions of the nervous system

Detailed Explanation

Main Components of Nervous System

The human nervous system consists of:

• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)

Central Nervous System (CNS)

• The CNS is a coordinating centre.
• It lies in the midline of the body.
• It consists of the brain and spinal cord.
• Both are hollow.
• The brain is enclosed within the cranium.
• The spinal cord is enclosed within the vertebral column.
• The brain and spinal cord are covered with three protective membranes called meninges.

Peripheral Nervous System (PNS)

• The PNS transmits information from receptors to CNS.
• It transmits orders and commands from CNS to effectors.
• It consists of nerves that branch out from the central nervous system and connect it to other body parts.
• It includes:
• Cranial nerves — arise from the brain
• Spinal nerves — arise from the spinal cord

Summary Table of Nervous System Components

Neurology

• The study of the structure and functions of the nervous system is called neurology.
• The term neurology comes from a combination of two words:
• "neuron" meaning nerve
• "logia" meaning "the study of"

Nervous Coordination

• Reception of stimulus
• Processing/analysis of information
• Response to stimulus

Summary of Nervous System Organization

Intermediate Level

Main Components of Nervous System

Central Nervous System (CNS)

Peripheral Nervous System (PNS)

Nervous Coordination

Neurology

Formula / Mathematical Form

Not applicable to this topic.

Solved Example

Not applicable to this topic (descriptive topic).

Important Points

• 1. Nervous system provides coordination through electric signals.
• 2. It consists of CNS and PNS.
• 3. CNS consists of brain and spinal cord.
• 4. CNS is a coordinating centre.
• 5. CNS lies in the midline of the body.
• 6. Brain is enclosed within the cranium.
• 7. Spinal cord is enclosed within the vertebral column.
• 8. Brain and spinal cord are covered with meninges.
• 9. Meninges are three protective membranes.
• 10. PNS transmits information from receptors to CNS.
• 11. PNS transmits orders and commands from CNS to effectors.
• 12. PNS includes cranial nerves and spinal nerves.
• 13. Cranial nerves arise from the brain.
• 14. Spinal nerves arise from the spinal cord.
• 15. Neurology is the study of the nervous system.
• 16. Nervous coordination has three steps.
• 17. Reception of stimulus is the first step.
• 18. Processing/analysis of information is the second step.
• 19. Response to stimulus is the third step.
• 20. The human nervous system is the most evolved among all animals.

Remember

• - Nervous system = provides coordination through electric signals
• - CNS = brain and spinal cord
• - PNS = cranial nerves and spinal nerves
• - **CNS** = coordinating centre
• - PNS = transmits information and commands
• - Meninges = three protective membranes
• - Cranium = encloses the brain
• - Vertebral column = encloses the spinal cord
• - Neurology = study of the nervous system
• - Nervous coordination = reception → processing → response

Common Mistakes

• 1. Confusing CNS and PNS — CNS = brain and spinal cord; PNS = nerves.
• 2. Thinking the PNS is the coordinating centre — CNS is the coordinating centre.
• 3. Mixing up the components of CNS — Brain and spinal cord.
• 4. Mixing up the components of PNS — Cranial nerves and spinal nerves.
• 5. Forgetting the role of meninges — Meninges are protective membranes.
• 6. Confusing the cranium and vertebral column — Cranium encloses brain; vertebral column encloses spinal cord.
• 7. Thinking the nervous system is only in the brain — It extends throughout the body.
• 8. Forgetting the three steps of nervous coordination — Reception, processing, response.
• 9. Mixing up the origin of cranial and spinal nerves — Cranial from brain; spinal from spinal cord.
• 10. Believing the nervous system is simple — It is highly complex and evolved.

Quick Revision

The human nervous system consists of central nervous system (CNS) and peripheral nervous system (PNS). The CNS is a coordinating centre and it lies in the midline of the body, whereas, the PNS transmits information from receptors to CNS and transmits orders and commands from CNS to effectors. The CNS consists of the brain and spinal cord. Both are hollow. The brain is enclosed within the cranium while the spinal cord is enclosed within the vertebral column. The brain and spinal cord are covered with three protective membranes called meninges. The PNS includes cranial nerves which arise from the brain and the spinal nerves, which arise from the spinal cord. Nervous coordination in higher animals consists of three basic steps: reception of stimulus, processing/analysis of information and response to stimulus. The study of the structure and functions of the nervous system is called neurology.

60-Second Revision

• Nervous system = provides coordination through electric signals
• CNS = brain and spinal cord
• PNS = cranial nerves and spinal nerves
• CNS = coordinating centre
• PNS = transmits information and commands
• Meninges = three protective membranes
• Cranium = encloses the brain
• Vertebral column = encloses the spinal cord
• Neurology = study of the nervous system
• Nervous coordination = reception → processing → response
• Warning: CNS is the coordinating centre; PNS transmits information and commands

NEXT TOPIC

• Chapter:
• 5. Nervous System of Man

• Topic:
• 5.7.1 ARCHITECTURE OF HUMAN BRAIN AND SPINAL CORD AND THEIR FUNCTIONS

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