B5 The Nervous Sytem

Question 1

What does the central nervous system do?

Answer 1

Coordinates a response

Question 2

What is the nervous system made up of?

Answer 2

Neutrons (nerve cells)

Question 3

Where do neutrons go?

Answer 3

To all parts of the body

Question 4

The body has lots of sensory receptors, what do they do?

Answer 4

Detect a change in your external or internal environment (a stimulus)

Question 5

Give 2 examples of the stimuli that different sensory receptors detect
(Eyes, skin)

Answer 5

Receptors in eyes detect light

Receptors in skin detect touch (pressure) and temperature changes

Question 6

What happens when a stimulus is detected by receptors?

Answer 6

The information is sent as nervous (electrical) impulses along sensory neurones to the central nervous system (CNS)

Question 7

What does the CNS consist of?

Answer 7

The brain and the spinal cord

Question 8

What does the CNS do?

Answer 8

It coordinates the response

Decides what to do about the stimulus and tells something to do it

Question 9

Where does the CNS send information to?

Answer 9

An effector (muscle or gland) along a motor neurone.

Question 10

What does the effector do?

Answer 10

It responds to the information from the CNS, eg. a muscle may contract or a gland may secrete a hormone.

Question 11

Complete the sentence

Nervous communication is very ……, but the response are short lived

Answer 11

Fast

Question 12

How do neurones transmit information?

Answer 12

Rapidly as electrical impulses

Question 13

Where are electrical impulses passed along ?

Answer 13

The axon of a neurone

Question 14

What are dendrites?

Answer 14

The branched endings of neurones.

Question 15

Why do neurones have branched endings (dendrites)?

Answer 15

So the can connect with lots of other neurone.

Question 16

What is myelin?

What does it do?

Answer 16

The fatty sheath that some axons are surrounded by.

It acts as an electrical insulator, speeding up the impulse.

Question 17

Why are neurones long?

Answer 17

This speeds up the impulse as connecting with another neurone slows the impulse down.

One long neurone is much quicker than lots of short ones joined together.

Question 18

What is the connection between two neurones called?

Answer 18

Synapse - it is a very tiny gap

Question 19

What does the electrical impulse trigger the release of?

Answer 19

Transmitter chemicals

Question 20

What do the transmitter chemicals do?

Answer 20

They diffuse across the synapse.

Bind to receptor molecules in the membrane of the next neurone, setting of a new electrical impulse.

Question 21

Complete the sentence

Reflex actions are………..

Answer 21

Involuntary

Question 22

Why are reflex actions involuntary?

Answer 22

They are done without thinking, so they’re even quicker than normal responses.

Question 23

What is the passage of information for a reflex action called?

Answer 23

Reflex arc

Question 24

Where does a reflex arc carry information from and to?

Answer 24

From receptor to effector

Question 25

Complete the sentence

The conscious brain isn’t involved in a ……..

Answer 25

Reflex arc.

Question 26

How does a reflex arc occur?

Answer 26

The sensory neurone connects to a relay neurone in the spinal cord or an unconscious part of the brain, which links directly to the right motor neurone.

Question 27

Why isn’t the conscious brain involved in a reflex arc?

Answer 27

So no time is wasted thinking about the response.

Question 28

What is the role of reflex actions?

Answer 28

Protective.

Eg. snatching back your hand when you touch a burning hot plate

Question 29

List the stages of the response to a bee sting to the finger 5

Answer 29

Bee stings finger

Stimulation of the pain receptor

Impulse travels along the sensory neurone

Impulse is passed along a relay neurone

Impulse travels along a motor neurone

When impulse reaches muscle, it contracts to move arm away from the bee.

Question 30

When might the conscious brain override a reflex response?

Answer 30

To stop us dropping a hit plate of food.

Question 31

Name the two main parts of the central nervous system (2marks)

Answer 31

Brain

Spinal cord