2.10.6 The Human Nervous System

Question 1

Central nervous system (CNS) consists of what?

Answer 1

The brain and spinal cord

Question 2

Peripheral nervous system (PNS) consists of what?

Answer 2

All of the nerves in the body

Question 3

Information is sent through the nervous system as what?

Answer 3

Electrical impulses

Question 4

These are electrical signals that pass along nerve cells known as what?

Answer 4

Neurones

Question 5

A bundle of neurones is known as what?

Answer 5

A nerve

Question 6

The nerves spread out from the central nervous system to where?

Answer 6

To all other regions of the body and importantly, to all of the sense organs

Question 7

The CNS, therefore, acts as a central coordinating centre for what?

Answer 7

The impulses that come in from (or are sent out to) any part of the body

Question 8

Neurones have a cell body (where the nucleus and main organelles are found) and cytoplasmic extensions from this body are called what?

Answer 8

Axons and Dendrites

Question 9

The Axon is the main what?

Answer 9

Long fibre of the neurone

Question 10

Some human neurones have axons of what length?

Answer 10

Over a metre in length (but only 1 – 4 micrometres wide)

Question 11

why is it more efficient than having multiple neurones to convey information from the CNS to effectors?

Answer 11

Less time is wasted transferring electrical impulses from one cell to another

Question 12

The axon is insulated by what?

Answer 12

A fatty myelin sheath with small uninsulated sections along its length (called nodes)

Question 13

The electrical impulse does not travel down the whole axon, what does it do?

Answer 13

It jumps from one node to the next

Question 14

Many extensions called dendrites extend out from where?

Answer 14

From the cell body of the neurone and at the far end of the axon

Question 15

This means neurones can connect to many other neurones and what?

Answer 15

Receive impulses from them, forming a network for easy communication

Question 16

Name the three main types of Neurones

Answer 16

Sensory neurones, relay neurones and motor neurones

Question 17

Sensory neurones carry impulses from where?

Answer 17

Sense organs to the CNS (brain or spinal cord)

Question 18

Relay neurones are found inside where?

Answer 18

The CNS and connect sensory and motor neurones

Question 19

Motor neurones carry impulses from where?

Answer 19

The CNS to effectors (muscles or glands)

Question 20

What is the structure of sensory neurones?

Answer 20

They are long and have a cell body branching off the middle of the axon

Question 21

What is the structure of relay neurones?

Answer 21

They are short and have a small cell body at one end with many dendrites branching off it

Question 22

What is the structure of motor neurones?

Answer 22

They are long and have a large cell body at one end with long dendrites branching off it

Question 23

The pathway through the nervous system is…

Answer 23

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

Question 24

First, a stimulus is received by what?

Answer 24

A sensory (receptor) neurone

Question 25

Most receptors are specialised to detect what?

Answer 25

Particular stimuli

Question 26

When a receptor is stimulated, it produces what?

Answer 26

Electrical impulses

Question 27

These impulses then travel along a sensory neurone to where?

Answer 27

Central nervous system (the coordinator is either the brain or the spinal cord)

Question 28

In the CNS, the impulses are passed on to what?

Answer 28

A relay neurone

Question 29

The relay neurone links to a motor neurone, along which the impulses travel until they reach what?

Answer 29

The effector

Question 30

What is the role of the effector?

Answer 30

It carries out the response (the effector may be a muscle or gland)