Select your language

Suggested languages for you:
Log In Start studying!
StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
|
|

All-in-one learning app

  • Flashcards
  • NotesNotes
  • ExplanationsExplanations
  • Study Planner
  • Textbook solutions
Start studying

Nervous System Divisions

Save Save
Print Print
Edit Edit
Sign up to use all features for free. Sign up now
Nervous System Divisions

Let's look at an example of our nervous system in action before defining nervous system divisions. In the English language, we hear about nerves a lot. “You get on my nerves” is a favourite expression levelled at annoying siblings, singing solo for the first time in front of people or having the last free throw in a basketball game are situations described as “nerve-wracking”. You can even be “nervy” and on edge or suffer from “nerves” before a date. So what is meant by these expressions?

Idioms including the word “nerve” refer to a physical response that includes shaking, heart racing, blushing and feelings of fear or tension caused by stimuli or things in our environment. These biological responses, such as the fight-or-flight response that makes us feel “nervous” in performance situations, are all due to our nervous system.


What is the definition of the nervous system?

The nervous system is a network in the body that is in charge of communication. All activity in the body is controlled by passing on information via its specialised cells, the neurones. Nerves, which the nervous system is named after, are bundles of neurones grouped together.

The two main functions of the nervous system are:

1. To receive sensory input, process it, and react to it.

2. To coordinate all the different elements in the body (cells, glands, etc.)

Depending on the location or the function of the different nerves, the nervous system can be subdivided again.

Biopsychology, Diagram of the division of the nervous system, StudySmarterDiagram of the divisions of the nervous system, StudySmarter Originals

Study tip: The nervous system is quite complex, and the divisions aren’t always clear cut, so there is some disagreement between researchers on the exact boundaries of the subdivisions of the nervous system. If in doubt, follow your specific textbook’s definitions.

What are the two main subdivisions of the nervous system?

  • Central nervous system (CNS) - This is the centre of control for the entire organism. The central nervous system includes the brain and spinal cord. It’s responsible for conscious decisions as well as automatic reactions (reflexes) to stimuli.

  • Peripheral nervous system (PNS) - The nervous system sends impulses from the peripherals to and from the central nervous system (CNS). The peripheral nervous system then is subdivided by function into the autonomic nervous system and the somatic nervous system. The autonomic nervous system can either be aroused or calmed. Depending on the response, it is overseen by the sympathetic nervous system (fight-or-flight response) and the parasympathetic nervous system (rest and digest response).

Study tip: In Biopsychology texts, acronyms of the names of the nervous system divisions are often used because the full names are so long. You can remember the different functions for the acronyms of the nervous system division like this: C, as in Control in the Central Nervous system. A, as in automatic in the autonomic nervous system.

What are the divisions of the central nervous system?

The central nervous system includes the brain and the spinal cord. This subsystem has physiological measures in place that prevent harmful toxins from entering the central nervous system. A specific plasma-like fluid circulates in and around the central nervous system called the cerebrospinal fluid (CSF). It has several molecular structures and membranes functioning as security gates, preventing toxins from entering the brain even if they’re already circulating in the body in substances such as blood. This means that although the brain and spinal cord connect to the other nerves, the central nervous system is a closed system in itself.

The brain

If you compare the size of other mammals to human brains, the human brain-to-body ratio is the same as that of a mouse or monkey. Therefore, if a rat or mouse were as tall as a human, their brains would be the same size as the human brain. Brains are very different from organism to organism - some animals don’t have a brain - such as a jellyfish. On the other hand, some animals, such as octopuses, have much larger brain-to-body ratios than humans.

However, the primary structural difference between humans and other animals is that the brain’s surface area, called the cerebral cortex, is much larger than that of other mammals. The human cortex is folded up, which is different from a rat’s smooth brain. The cerebral cortex’s increased surface area makes humans better at integrating information and planning than other animals. Conscious and unconscious decisions are made in the brain. The brain stem connects the brain to the spinal cord.

The spinal cord

The spinal cord is a tubular structure of nerves that extend from the brain into the peripheral nervous system. It reaches from the base of the brain called the hindbrain to the second lumbar vertebra in the lower back, about 5 cm above the pelvis.

To enable the body to react quickly, specialised neurones, called relay neurons, carry out unconscious reactions to stimuli known as reflexes. Pulling your hand away from a hot plate, jumping when startled, and your knee-jerking up when a doctor hits it are all examples of reflexes. The spinal cord includes the nerve endings that serve as connectors to the peripheral nervous system.

What are the divisions of the peripheral nervous system?

In the peripheral nervous system, nerves extend from clusters of neurone cell bodies called ganglions into all the muscles and senses in the body. In the PNS, information gets passed to the CNS and from the CNS to muscles and organs. It’s here that the information taken in by the senses (smell, taste, sight), and receptors (touch, heat, pain) are passed to the CNS for integration.

These two different aspects are subdivided again into the somatic nervous system and the autonomic nervous system. These two divisions of the nervous system run parallel to each other (they are not divided by location).

  • Somatic nervous system: This part of the peripheral nervous system communicates with your senses (“soma”). It also is responsible for the voluntary control of your muscles. Any activity that you consciously control, such as moving fingers or speaking, fall under the banner of the somatic nervous system.

  • Autonomic nervous system: This is the part of the peripheral nervous system in charge of the involuntary and unconscious control of processes of the body such as heart rate, blinking, digestion, relaxation and arousal. It works autonomously and is controlled by a specific part of the brain called the Hypothalamus. The autonomic nervous system can again be divided into two functional units.

What are the two subdivisions of the autonomic nervous system?

The nervous system, sympathetic and parasympathetic nervous systems, StudysmarterParasympathetic and sympathetic nervous systems and their effect on the body, wikimediacommons

The sympathetic and parasympathetic nervous systems are functional divisions of the autonomic nervous system that are automatically activated in response to stimuli.

  • The sympathetic nervous system (responsible for “fight, flight or freeze”): the part of the autonomic nervous system that is also called the fight-or-flight response (or in more modern textbooks, fight, flight or freeze response). It mobilises the organism in response to stimuli perceived as dangerous to be able to fight the danger or flee from it. When activated, the sympathetic nervous system causes pupils to dilate, allowing for a better perception of light. It makes the body release stress hormones into the bloodstream, which mobilises carbohydrates in the body for energy. The heart rate increases to get more energy to all parts of the body quickly to carry out fast movements. So if you hear a bump in the night and your heart starts racing, and your breathing is rapid, the sympathetic nervous system is the nervous system division responsible.

Study tip: Freezing in light of danger is widely acknowledged in the medical community, but it hasn't worked its way into the A-Level syllabus yet.

  • The parasympathetic nervous system (responsible for “rest and digest”): the part of the autonomic nervous system that returns the body to its homeostasis (biological balance) by counteracting the sympathetic nervous system. It slows the heart rate and breathing and blocks stress hormones. This is the body's response when the organism knows it’s safe and can now eat and sleep in peace and safety without danger. So when you’ve just had a massage or have just finished working out, this is the nervous system division responsible for that feeling of deep relaxation you feel afterwards.

The nervous system - Key takeaways

  • Nerves are a group of neurones. A cluster of neurone cell bodies is a ganglion.
  • The nervous system is a system of the body in charge of communication.
  • The two main functions of the nervous system are receiving, processing and reacting to sensory input, and coordinating cells and organs in the body.
  • There are two main divisions of the nervous system, the peripheral nervous system and the central nervous system.
  • The central nervous system includes the brain and spinal cord and is responsible for conscious and unconscious control of the body.
  • The peripheral nervous system includes communication pathways to all parts of the body that aren’t part of the central nervous system.
  • The peripheral nervous system is split into voluntary and involuntary systems- the autonomic nervous system in charge of automatic functions and the somatic nervous system in charge of voluntary movement.
  • The autonomic nervous system is subdivided into the parasympathetic and sympathetic nervous systems.
  • The sympathetic nervous system is our fight-or-flight response.
  • The parasympathetic nervous system is our rest-and-digest response.


Frequently Asked Questions about Nervous System Divisions

The sympathetic division of the autonomic nervous system has short preganglionic neurones.

The autonomic nervous system is divided into the sympathetic and the parasympathetic nervous systems.

The nervous system has three functions- sensing, processing and reacting. When divided by functions, the functions depend on the types of neurones [crosslink].

The main divisions of the central nervous system are the brain and the spinal cord.

The peripheral nervous system is a division of the nervous system that includes all parts of the nervous system except the brain and spinal cord.

Final Nervous System Divisions Quiz

Question

What is a nerve?



Show answer

Answer

A group of neurones.

Show question

Question

What is the nervous system?




Show answer

Answer

A network in the body in charge of 

communication.

Show question

Question

Which one of these is not a main function of the nervous system?



Show answer

Answer

 Receive, process and react to sensory input.



Show question

Question

Whate are the 6 subdivisions of the nervous system?



Show answer

Answer


1. Central nervous system

2. Peripheral nervous system

3. Autonomic nervous system

4. Somatic nervous system

5. Sympathetic nervous system

6. Parasympathetic nervous system


Show question

Question

Which nervous system connects the central nervous system to the muscles?



Show answer

Answer

The peripheral nervous system connects the central nervous system to the muscles.

Show question

Question

Which nervous system includes the spinal cord?




Show answer

Answer

The central nervous system includes the brain and spinal cord.

Show question

Question

What is the liquid that is only found in the central nervous system?




Show answer

Answer

The liquid that can only be found in the central nervous system is called the cerebrospinal fluid.

Show question

Question

What is the primary function of the brain?



Show answer

Answer

All conscious and unconscious decisions in the organism are made in the brain.


Show question

Question

Which nervous system division controls reflexes?




Show answer

Answer

The central nervous system controls reflexes- specifically relay neurones in the spinal cord.

Show question

Question

 Which nervous system division controls voluntary movement?




Show answer

Answer

The somatic nervous system controls voluntary movement.

Show question

Question

Which nervous system division controls automatic 

movements in the body, such as your heartbeat and blinking?



Show answer

Answer

The autonomic nervous system controls automatic movements.

Show question

Question

Which two responses are controlled by the autonomic nervous system?



Show answer

Answer

The autonomic nervous system controls the sympathetic and the parasympathetic nervous systems.


Show question

Question

 True or false: The parasympathetic nervous system is also called our fight-or-flight response.



Show answer

Answer

False - the parasympathetic nervous system is also called our rest-and-digest response.



Show question

Question

 True or false: The sympathetic nervous system helps mobilise the body to respond to perceived danger.



Show answer

Answer

True, the faster heartbeat and increased circulation help mobilise the body to react to perceived danger.



Show question

Question

Sometimes people faint after receiving an injection. Without them having any control over it, their heart rate and blood pressure suddenly drop, and they feel light-headed and dizzy. Which nervous system is most likely responsible for this response?



Show answer

Answer

The parasympathetic nervous system as part of the autonomic nervous system is responsible for the fainting reaction (medically: vasovagal syncope).



Show question

60%

of the users don't pass the Nervous System Divisions quiz! Will you pass the quiz?

Start Quiz

Discover the right content for your subjects

No need to cheat if you have everything you need to succeed! Packed into one app!

Study Plan

Be perfectly prepared on time with an individual plan.

Quizzes

Test your knowledge with gamified quizzes.

Flashcards

Create and find flashcards in record time.

Notes

Create beautiful notes faster than ever before.

Study Sets

Have all your study materials in one place.

Documents

Upload unlimited documents and save them online.

Study Analytics

Identify your study strength and weaknesses.

Weekly Goals

Set individual study goals and earn points reaching them.

Smart Reminders

Stop procrastinating with our study reminders.

Rewards

Earn points, unlock badges and level up while studying.

Magic Marker

Create flashcards in notes completely automatically.

Smart Formatting

Create the most beautiful study materials using our templates.

Just Signed up?

Yes
No, I'll do it now

Sign up to highlight and take notes. It’s 100% free.