B1d-the nervous system Flashcards Preview

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Flashcards in B1d-the nervous system Deck (31)
1

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

Using receptors which generate nerve impulses

2

What does cornea do?

Refract light

3

What does iris do?

Controls how much light enters pupil

4

What does lens do?

Focuses light onto retina

5

What does retina do?

Contains light receptors, some sensitive to light of different colours

6

What does optic nerve do?

Carries impulses to the brain

7

What is the pathway of light?

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

8

What is accommodation?

The eye focusing light by changing shape of lens

9

How does the eye focus on distant objects?

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

10

How does the eye look at near objects?

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

11

What is monocular vision?

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

12

What is binocular vision?

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

13

How does binocular vision help to judge distances?

-brain compares two images
-more similarities, further away the object

14

What is the cause of red green colour blindness?

Lack of specialised cone cells in retina

15

What is short sightedness?

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

16

What is long sightedness?

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

17

What kind of lenses are used to correct short sightedness?

Concave

18

What kind of lenses are used to correct long sightedness?

Convex

19

What is a nerve impulse?

An electrical signal that is carried by nerve cells called neurones

20

What are reflex actions?

Fast,automatic and protective responses

21

What are voluntary responses?

Responses that are under the conscious control of the brain

22

What are the parts of a motor neurone?

Cell body
Axon
Sheath

23

What happens on the axon of a neurone?

Nerve impulses pass along the axon

24

What is the pathway of a reflex arc?

Stimulus
Receptor
Sensory neurone
Central nervous system
Motor neurone
Effector
Response

25

What is the pathway for an involuntary response?

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

26

How does the length of neurone help their function?

They're long which speeds up the impulse

27

How does a neurones insulating sheath help their function?

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

28

How do neurones dendrites help their function?

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

29

What is a synapse?

The gap between neurones

30

What does an impulse trigger in a synapse?

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

31

What does an impulse trigger in a synapse?

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