B1d-the nervous system

Question 1

How do animals detect changes in their environment(stimuli) ?

Answer 1

Using receptors which generate nerve impulses

Question 2

What does cornea do?

Answer 2

Refract light

Question 3

What does iris do?

Answer 3

Controls how much light enters pupil

Question 4

What does lens do?

Answer 4

Focuses light onto retina

Question 5

What does retina do?

Answer 5

Contains light receptors, some sensitive to light of different colours

Question 6

What does optic nerve do?

Answer 6

Carries impulses to the brain

Question 7

What is the pathway of light?

Answer 7

Eyeball
Refracted by cornea and lens
Brought to focus on the retina

Question 8

What is accommodation?

Answer 8

The eye focusing light by changing shape of lens

Question 9

How does the eye focus on distant objects?

Answer 9

• ciliary muscle relaxes
• suspensory ligaments pull tight
• lens less rounded light refracted less

Question 10

How does the eye look at near objects?

Answer 10

Ciliary muscles contracts
Suspensory ligament slackens
Lens more rounded light refracted more

Question 11

What is monocular vision?

Answer 11

Eyes on each side of head
Wider field of view
poorer judgement of distance

Question 12

What is binocular vision?

Answer 12

• eyes side by side
• narrow field of view
• good judgement of distance

Question 13

How does binocular vision help to judge distances?

Answer 13

• brain compares two images

- more similarities, further away the object

Question 14

What is the cause of red green colour blindness?

Answer 14

Lack of specialised cone cells in retina

Question 15

What is short sightedness?

Answer 15

Lens bends light too much
Images focused in front of retina
Cant see far away

Question 16

What is long sightedness?

Answer 16

Lens doesn’t bend light enough
Images focused behind retina
Cant see close up

Question 17

What kind of lenses are used to correct short sightedness?

Answer 17

Concave

Question 18

What kind of lenses are used to correct long sightedness?

Answer 18

Convex

Question 19

What is a nerve impulse?

Answer 19

An electrical signal that is carried by nerve cells called neurones

Question 20

What are reflex actions?

Answer 20

Fast,automatic and protective responses

Question 21

What are voluntary responses?

Answer 21

Responses that are under the conscious control of the brain

Question 22

What are the parts of a motor neurone?

Answer 22

Cell body
Axon
Sheath

Question 23

What happens on the axon of a neurone?

Answer 23

Nerve impulses pass along the axon

Question 24

What is the pathway of a reflex arc?

Answer 24

Stimulus
Receptor
Sensory neurone
Central nervous system
Motor neurone
Effector
Response

Question 25

What is the pathway for an involuntary response?

Answer 25

Stimulus 
Receptor
Sensory neurone
Relay neurone in spinal cord
Motor neurone
Effector
Response

Question 26

How does the length of neurone help their function?

Answer 26

They’re long which speeds up the impulse

Question 27

How does a neurones insulating sheath help their function?

Answer 27

The sheath along the axon acts as an electrical insulator which speeds up the electrical impulse

Question 28

How do neurones dendrites help their function?

Answer 28

These branched endings means they can connect with lots of other neurones

Question 29

What is a synapse?

Answer 29

The gap between neurones

Question 30

What does an impulse trigger in a synapse?

Answer 30

An impulse triggers the release of a transmitter substance in a synapse and it diffuses across to bind with receptor molecules in the membrane of the next neurone causing the impulse to continue

Question 31

What does an impulse trigger in a synapse?

Answer 31

An impulse triggers the release of a transmitter substance in a synapse and it diffuses across to bind with receptor molecules in the membrane of the next neurone causing the impulse to continue