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The Nervous System

The Nervous System Overview

The nervous system is a complex network responsible for coordinating the body’s responses to internal and external stimuli. It is divided into two main parts: the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

System Organization Outline

1

The Central Nervous System (CNS)

The CNS is composed of the brain and spinal cord.
2

The Peripheral Nervous System (PNS)

Includes all nerves outside the CNS.

CNS Role: Processing and Control

The CNS is composed of the brain and spinal cord. It functions as the control centre of the body and is responsible for processing information received from sensory organs and initiating appropriate responses. The brain interprets information, generates thoughts, emotions, and decisions. The spinal cord acts as a conduit between the brain and the rest of the body and also manages reflex actions.

The Peripheral Nervous System (PNS)

The PNS includes all nerves outside the CNS. Its main role is to connect the CNS to limbs and organs, facilitating communication between the brain and spinal cord and the rest of the body. The PNS itself is divided into two systems:

A

Somatic Nervous System (SNS)

Responsible for voluntary control over skeletal muscles.
B

Autonomic Nervous System (ANS)

Regulates involuntary bodily functions.

The Somatic Nervous System (SNS)

✋

Voluntary Control: The SNS is responsible for voluntary control over skeletal muscles. It includes sensory neurons that carry messages from sensory organs to the CNS, and motor neurons that send impulses from the CNS to muscles. For example, deciding to move your hand away from a hot surface involves the SNS. It allows conscious control and interaction with the environment.

The Autonomic Nervous System (ANS)

ANS = Homeostasis Maintenance
The ANS regulates involuntary bodily functions such as heart rate, digestion, respiratory rate, and glandular activity. It operates automatically without conscious thought, maintaining internal homeostasis.

ANS Subdivisions: Opposing Actions

🔥
SYMPATHETIC NERVOUS SYSTEM This is involved in the 'fight or flight' response, preparing the body for stressful or threatening situations. It increases heart rate, dilates pupils, inhibits digestion, and redirects blood flow to muscles.
🌿
PARASYMPATHETIC NERVOUS SYSTEM This branch promotes 'rest and digest' activities, conserving energy and restoring the body to a calm state after stress. It decreases heart rate, stimulates digestion, and promotes relaxation.

System Interactions

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Sensory input collected by the PNS is sent to the CNS for processing.
🗣️
Motor commands from the CNS are sent back through the PNS to execute actions.

In Summary: Core Functions

The nervous system is organized into the CNS and PNS, where the CNS processes information and the PNS connects the CNS to the rest of the body. The division further into somatic and autonomic allows for both voluntary and involuntary control, ensuring the body responds appropriately both consciously and unconsciously.

🧠

CNS

Processes information.
🌐

PNS

Connects CNS to body.
💪

Somatic

Voluntary control.
⚙️

Autonomic

Involuntary control.
The Nervous System Deck
Term
Main Parts of Nervous System

What are the two main parts of the nervous system?

Answer
Components

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

Term
CNS Organs

What organs make up the CNS?

Answer
Organs

The brain and spinal cord.

Term
CNS Primary Function

What is the primary function of the CNS?

Answer
Function

To process information and control the body’s responses.

Term
PNS Role

What does the PNS do?

Answer
Role

Connects the CNS to limbs and organs for communication.

Term
PNS Divisions

Into which two systems is the PNS divided?

Answer
Divisions

Somatic Nervous System (SNS) and Autonomic Nervous System (ANS).

Term
Somatic Nervous System

What does the Somatic Nervous System control?

Answer
Control

Voluntary control of skeletal muscles.

Term
Autonomic Nervous System Functions

What type of functions does the Autonomic Nervous System regulate?

Answer
Functions

Involuntary functions like heart rate and digestion.

Term
ANS Branches

What are the two branches of the ANS?

Answer
Branches

Sympathetic Nervous System and Parasympathetic Nervous System.

Term
Sympathetic Nervous System

What does the Sympathetic Nervous System do?

Answer
Function

Prepares the body for fight or flight responses.

Term
Parasympathetic Nervous System

What is the role of the Parasympathetic Nervous System?

Answer
Role

Promotes rest and digest activities.

Term
CNS & PNS Interaction

How do the CNS and PNS interact?

Answer
Interaction

The PNS sends sensory input to the CNS; the CNS sends motor commands back through the PNS.

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🧠 The Nervous System Quiz

1. What are the two main parts of the nervous system?

The nervous system is divided into the Central Nervous System and Peripheral Nervous System.

2. Which part of the nervous system is responsible for voluntary muscle control?

The Somatic Nervous System controls voluntary skeletal muscle movements.

3. The “fight or flight” response is managed by which nervous system?

The Sympathetic Nervous System activates the fight or flight response.

4. The brain and spinal cord make up which system?

The brain and spinal cord form the Central Nervous System.

5. Which division of the nervous system controls involuntary bodily functions such as digestion and heart rate?

The ANS regulates involuntary functions like heart rate and digestion.

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