2.7 - The nervous system

Question 1

What does the human nervous system consist of?

Answer 1

Central nervous system (CNS) - brain, spinal chord.

Peripheral nervous system - nerve cells carry info to or from CNS.

Question 2

What are nerve cells also known as?

Answer 2

Neurones

Question 3

What are neurones?

Answer 3

long cells that carry electrical signals along their length

Question 4

Where two neurones meet there is a tiny gap called a …

Answer 4

Synapse - a chemical (diffusion) signal that travels across the synapse to the next neurone.

Question 5

How does information flow from the receptors to the effectors?

Answer 5

Receptors –(sensory neurons)–> CNS —-(motor neurons)–> Effectors

Question 6

What do are sense organs detect?

Answer 6

Changes in the world around us known as stimuli

Question 7

What is a stimulus?

Answer 7

Something that sets of a reaction in the nervous system (light, temp, sound). These changes in environment are detected by receptors in an organism.

Question 8

What do sense organs contain?

Answer 8

Groups of specialised cells called receptor cells which produce electrical impulses in response to specific stimuli.

Question 9

What are the stimulus of these five sense organs?
Skin
Tongue
Nose
Eye
Ear

Answer 9

Touch, temperature
Chemicals (in food and drink)
Chemicals (in air)
Light
Sound

Question 10

What are effectors?

Answer 10

Parts of the body, such as muscles or glands, that produce a response to a detected stimulus.

Question 11

Give examples of effectors in use?

Answer 11

muscle contracting to move an arm
muscle squeezing saliva from salivary gland
A gland releasing a hormone into the blood

Question 12

What is the order of how information flows from receptors to effectors?
Stimulus,_____,____ neuron,____ neuron, ____ neuron,_____, response

Answer 12

Stimulus -> receptor -> sensory neuron -> relay neuron -> motor neuron -> effector -> response

Question 13

What is a reflex action?

Answer 13

A protective, automatic and rapid response to a stimulus

Question 14

The nerve pathway followed by a reflex action is called a…

Answer 14

Reflex arc

Question 15

What happens when you accidently touch something hot?

Answer 15

1) receptor in skin detects a stimulus (heat)
2) sensory neuron sends impulse to relay neuron in the spinal cord
3) The relay neuron connects to the motor neuron (and also sends a message to the brain)
4) motor neurons sends impulses to effector
5) effector produces a response ( muscle contracts to move hand away)

Question 16

When there is a bright light in your eye what happens to your:
Radial muscles
Circular muscles
Pupil

Answer 16

Radial muscles - relaxed
Circular muscles - contracted
Pupil - contracted (less light enters eye)

Question 17

When there is a dim light in your eye what happens to your:
Radial muscles
Circular muscles
Pupil

Answer 17

Radial muscles - contracted
Circular muscles - relaxed
Pupil - relaxed (more light enters)

Question 18

The reaction of light in an eye is protective, involuntary and rapid. What do these words mean?

Answer 18

Protective - prevents harmful bright light from damaging the receptor cells at the back of the eye
Involuntary - you don’t have to think about it, it happens automatically
Rapid - the reaction happens very quickly

Question 19

Once the stimulus is detected the following process occurs:

Answer 19

1) A receptor cell passes an electrical impulse along the sensory neurone.
2) The sensory neurone reaches the coordinator ( determines correct response to stimulus), the CNS.
3) The sensory neurone connects to a relay neurone, via a synapse, inside the CNS.
4) The relay neurone connects to a motor neurone, via a synapse, inside the CNS.
5) The motor neurone leaves the CNS and the impulse is carried to the effector.

Question 20

What are the functions in the eye of the following structures?
Cornea
Iris
Lens

Answer 20

Cornea - refracts light - bend it as it enters eye
Iris - controls how much light enters pupil
Lens - focuses light onto the retina

Question 21

What are the functions in the eye of the following structures?
Retina 
Optic nerve 
Sclera
Pupil

Answer 21

Retina - contains the light receptors
Optic nerve - carries impulses between the eye and brain
Sclera - white, tough outer layer
Pupil - small hole at center of Iris that allows light in eye