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Compare the Parts of the Nervous System

Worksheet Overview

QUESTION 1 of 10

Image of toilet

 

 

Did you know that we need our nervous system to pee?! 

The nervous system is a system that allows us to control our body and gives us feedback about the world. Without it, we would struggle to do basic things like going to the toilet!

 

Image of the nervous system

 


The nervous system is made up of two parts: 

The central nervous system (CNS),  which includes the brain and spinal cord.

The peripheral nervous system (PNS), which are the nerves that carry information to and from the CNS. 

 

So how does the nervous system work exactly? 

We react to changes in the environment, so if it's really bright and sunny outside we might squint and turn away from the sun. We would call the sunlight in this example a stimulus. It's a change in your environment which you need to react to. Other examples might be sound or smell. Our sense organs detect the stimuli - these organs are our eyes, ears, nose, tongue and skin. Our sense organs all contain different receptors. 


Receptors are groups of cells which are sensitive to stimuli. They change stimulus energy (e.g. light energy) into electrical impulses. These impulses are passed along neurones (you'll find out more about neurones below) to the central nervous system (often referred to as the coordinator). The neurones then pass the impulses to effectors, which are often muscles and glands. A reaction is then made, such as moving your head away from direct sunlight, in the example given above. This pathway can be demonstrated in a flow diagram like the one below:

 

 

 

A nerve cell or neurone has many features. One of its features is a tail-like structure called the axon, which can be really long. This allows nerve impulses to travel all around the body at lightning-fast speed. The axon also allows nerve impulses to be passed along to other effector cells, such as muscles, or to other neurones. Where the neurones meet, there is a gap called a synapse. It's here where a  specific chemical, called a neurotransmitter, diffuses across the synapse to pass on the impulse. This makes sure the nerve impulse goes where it's meant to - imagine touching something hot with your hand and then moving your leg instead! 


Neurones are covered in a blanket of fatty cells called the myelin sheath. This helps to protect the nerve cell from damage and helps speed up the transmission of nerve impulses.

Another feature of the nerve cell is the dendrons. Dendrons are branches (that further divide into dendrites) that receive nerve impulses from other nerve cells.

 

Image of a nerve

 

 

There are three types of neurones: sensory, motor and relay.  Sensory neurones pass on impulses from our senses to the CNS, whereas motor neurones pass on impulses from the coordinator (normally the CNS)  to muscles or glands (the effectors). Relay neurones connect the sensory neurone to the motor neurone - they're found in the spinal cord and so don't need to travel to the brain.  

 

Image of different neurones  

 

What are reflexes?

Reflexes are designed to allow you to respond to a potentially dangerous situation very quickly. As there is no time to think, the brain doesn't need to be involved in making a conscious decision. These actions are still coordinated by the CNS, but by the spinal cord rather than the brain.


Voluntary responses are ones that require the brain to decide on a conscious response, so take longer than reflexes. A reflex arc isn't needed in a voluntary response.

 

Image of relay arc

 


Reflexes need to happen really fast - this way you're protected from harm. For example, if you  touch a hot pan, your reflexes cause you to pull your hand away really quickly before you burn yourself. 


The pathway that is followed in a reflex action is called a reflex arc:

stimulus → receptor→ sensory neurone →relay neurone → motor neurone → effector→ response


 

In the example of touching a hot pan:

The hot pan is the stimulus → detected by receptor cells in the fingertips → nervous impulse from fingertips to sensory neurone → impulse sent to relay neurone in spinal cord → impulse is passed onto motor neurone  → passed onto the effector which is the muscles in the fingers → response is moving the hand away from the hot pan.


Reflexes are known to be autonomic - they don't require any conscious thought, and our body relies on these for things like heart rate, blood pressure and metabolism. 


In the following activity, you will investigate the different parts of the nervous system.

What are the functions of all the parts of the nervous system listed below?

Column A

Column B

Sensory neurone
Passes on impulses from sense organs to the coordi...
Synapse
The gap that allows impulses to pass to another ne...
Relay neurone
Passes impulses to an effector
Motor neurone
Neurone that connects a sensory and motor neurone

How do the different parts of a motor neurone work together to ensure the nerve cell is highly specialised? 

Nerve cells receive impulses from other cells via the axons, which are then transmitted away from the cell body down the myelin sheath. This happens very slowly due to the insulation provided by the myelin sheath

Nerve cells receive impulses from the coordinator via the dendrites, which are then transmitted down the axon. This happens very fast due to the insulation provided by the myelin sheath

Nerve cells receive impulses from other cells via the dendrites, which are then transmitted away from the cell body down the tail. This happens very fast due to the insulation provided by the myelin sheath

What parts of the body are labelled A and B in the image below?

 

Image of the CNS 

A: The spinal cord - part of the CNS

A: The brain - part of the CNS

B: Muscles - part of the PNS

B: Nerves - part of the PNS

Reflexes are autonomic, they keep us safe and control so many vital processes like our heart rate.

 

The image below shows a reflex arc. Label A, B and C. 

 

Image of relay arc

Column A

Column B

A
Effector/muscle
B
Sensory neurone
C
Receptor

What is the name of the junction between the two neurones in the picture below?

 

Image of reflex arc and synapse

Label the parts 1, 2, and 3 of the nerve pathway below:

 

Image of nerve pathway

 123
Response
Stimulus
Central nervous system

Receptors and effectors are really important parts of the nervous system. 

 

What is the difference between a receptor and an effector?

Receptors detect stimuli found in sense organs and pass on a nerve impulse to sensory neurones

Receptors bring about a response

Effectors are found in our sense organs and detect stimuli

Effectors are usually organs or glands that bring about a response

What are some of the differences between sensory neurones, motor neurones and relay neurones?

 Sensory neuroneMotor neuroneRelay neurone
Often used in a reflex arc
Sends nerve impulses from receptors to the CNS
Sends impulses from the CNS to an effector
Connects a sensory neurone to a motor neurone

What is the difference between a reflex and a voluntary response?

 Sensory neuroneMotor neuroneRelay neurone
Often used in a reflex arc
Sends nerve impulses from receptors to the CNS
Sends impulses from the CNS to an effector
Connects a sensory neurone to a motor neurone

The dendrites, axon and myelin sheath all help the nerve cell to transmit nerve impulses across the body.

 

Compare the jobs of the dendrites, axon and myelin sheath. 

 

Image of a nerve

Column A

Column B

Myelin sheath
Fatty covering to protect the nerve and allow spee...
Axon
Tiny branches to receive nerve impulses from other...
Dendrites
Long structure to allow nerve transmission around ...
  • Question 1

What are the functions of all the parts of the nervous system listed below?

CORRECT ANSWER

Column A

Column B

Sensory neurone
Passes on impulses from sense org...
Synapse
The gap that allows impulses to p...
Relay neurone
Neurone that connects a sensory a...
Motor neurone
Passes impulses to an effector
EDDIE SAYS
These are really key terms you need to remember, so have a few tries in order to consolidate your learning. There are a few tips that might help you to remember which is which. The sensory neurone is to do with your senses and is connected to your sense organs. The motor neurone is to do with movement - the impulses may trigger a movement. The relay neurone passes an impulse on - just like passing the baton on during a relay race!
  • Question 2

How do the different parts of a motor neurone work together to ensure the nerve cell is highly specialised? 

CORRECT ANSWER
Nerve cells receive impulses from the coordinator via the dendrites, which are then transmitted down the axon. This happens very fast due to the insulation provided by the myelin sheath
EDDIE SAYS
Don't despair if you weren't too sure with this one. There was a lot to think about with all these options. These different parts of the nerve cell make it really specialised and suited to its job. Dendrites are the tiny branches that receive impulses and pass them along to the axon. Remember, the axon looks like a tail (it's not a tail though, so don't write that in an exam!) and the myelin sheath is a fatty covering surrounding the axon. The impulse travels down the axon to the synapse, where it is passed along to an effector cell - a muscle cell, for example.
  • Question 3

What parts of the body are labelled A and B in the image below?

 

Image of the CNS 

CORRECT ANSWER
A: The brain - part of the CNS
B: Nerves - part of the PNS
EDDIE SAYS
Don't forget, there are two parts to the nervous system. The CNS is made up of the spinal cord and the brain - marked A in the image. The PNS - the peripheral nervous system - includes the nerves (marked B) that connect up to the CNS. The PNS is the network of nerves that eventually connect up to the CNS.
  • Question 4

Reflexes are autonomic, they keep us safe and control so many vital processes like our heart rate.

 

The image below shows a reflex arc. Label A, B and C. 

 

Image of relay arc

CORRECT ANSWER

Column A

Column B

A
Receptor
B
Sensory neurone
C
Effector/muscle
EDDIE SAYS
The trick is to remember that after the stimulus, a nerve pathway will always start with a receptor and end with the effector, which brings about a response. Does it help you if you remember that both end and effector start with the same letter?!
  • Question 5

What is the name of the junction between the two neurones in the picture below?

 

Image of reflex arc and synapse

CORRECT ANSWER
synapse
a synapse
the synapse
EDDIE SAYS
The synapse helps nerve impulses to be passed on quickly to other neurones. They are highly specific, so it means that nerve impulses travel to where they're meant to.
  • Question 6

Label the parts 1, 2, and 3 of the nerve pathway below:

 

Image of nerve pathway

CORRECT ANSWER
 123
Response
Stimulus
Central nervous system
EDDIE SAYS
Take the time to remember the different parts of the nerve pathway! You could try a mnemonic maybe: Silly Riddles Create Excellent Results Stimulus → Receptors → CNS → Effector → Response
  • Question 7

Receptors and effectors are really important parts of the nervous system. 

 

What is the difference between a receptor and an effector?

CORRECT ANSWER
Receptors detect stimuli found in sense organs and pass on a nerve impulse to sensory neurones
Effectors are usually organs or glands that bring about a response
EDDIE SAYS
To help you remember: receptors receive information about the world around us via our senses, effectors bring about an effect - they cause something to happen.
  • Question 8

What are some of the differences between sensory neurones, motor neurones and relay neurones?

CORRECT ANSWER
 Sensory neuroneMotor neuroneRelay neurone
Often used in a reflex arc
Sends nerve impulses from receptors to the CNS
Sends impulses from the CNS to an effector
Connects a sensory neurone to a motor neurone
EDDIE SAYS
This activity should help you to review key differences between the different types of neurones - great revision for exams!
  • Question 9

What is the difference between a reflex and a voluntary response?

CORRECT ANSWER
EDDIE SAYS
How did you get on with all these blanks to fill in? Voluntary means something that's been chosen, kind of the opposite to a reflex where you have no control over the response. A reflex has to be an immediate response to a stimulus in order to avoid possible injury. Our bodies do have several reflex actions which we have no control of - one of these is the pupils in our eyes which contract in bright sunlight.
  • Question 10

The dendrites, axon and myelin sheath all help the nerve cell to transmit nerve impulses across the body.

 

Compare the jobs of the dendrites, axon and myelin sheath. 

 

Image of a nerve

CORRECT ANSWER

Column A

Column B

Myelin sheath
Fatty covering to protect the ner...
Axon
Long structure to allow nerve tra...
Dendrites
Tiny branches to receive nerve im...
EDDIE SAYS
Don't worry if you find it hard to remember these tricky words. The more you see them written, the easier it will become to remember how to spell them and what they are! The dendrites are branches that receive impulses from other nerve cells. These will then travel down the axon, which is surrounded by the fatty sheath. The myelin sheath of a nerve cell is really important for two reasons. Firstly, it offers protection for the nerve cell, but its main function is to help the nerve impulses to travel super fast. With the axon being long, nerves can travel around the body easily. How did you get on with this activity? If you're still finding this topic hard, why not go back and read the Introduction and give the questions another try?
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