Coordination and Response

Question 1

What is a nerve impulse?

Answer 1

An electrical signal that passes along nerve cells called neurons

Question 2

What does a receptor do?

Answer 2

Detects a change in stimulus

Question 3

What does the central nervous system consist of?

Answer 3

Brain and spinal cord

Question 4

What does the peripheral nervous system contain?

Answer 4

Every other part- nerves

Question 5

Define voluntary action

Answer 5

An action completed with conscious thought and under our own will

Question 6

Define involuntary action

Answer 6

An action completed without conscious thought

Question 7

What is a relay neurone?

Answer 7

Short and are located in the CNS , connecting sensory and motor neurones

Question 8

What is a sensory neurone?

Answer 8

Long and have a cell body branching off the middle of an axon. Carry impulses from sense organ to CNS

Question 9

What is a motor neurone?

Answer 9

Long and have a cell body at one end with long dendrites branching off. Carry impulses from the CNS to muscles and glands.

Question 10

Describe the simples reflex arc

Answer 10

1. Stimulus is detected by receptor in the skin
2. Sensory neurone sends electrical impulses to spinal cord
3. Electrical impulse is passed on to a relay neurone in spinal cord
4. Relay neurone carries impulse to motor neurone which carries it to a muscle in the arm
5. Muscle contracts and pulls hand up and away from hot object

Question 11

Define reflex action

Answer 11

Automatically and rapidly integrating and coordinating stimuli with the responses of effectors

Question 12

Define synapse

Answer 12

Junction between two neurones

Question 13

Describe a synapse

Answer 13

The impulse reaches the end of one neurone
Vesicles release neurotransmitters into synaptic gap
Neurotransmitter diffuses across gap and binds with receptors
New impulse is triggered in the next neurone

Question 14

What do synapses ensure?

Answer 14

That impulses travel in one direction only

Question 15

What substances affect synapses?

Answer 15

Heroin
alcohol
nicotine

Question 16

Define sense organs

Answer 16

Groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals

Question 17

What does the cornea do?

Answer 17

Refracts light and helps to focus it

Question 18

What does the iris do?

Answer 18

Controls how much light enters the pupil

Question 19

What does the lens do?

Answer 19

Refracts light to focus it into the retina

Question 20

What does the retina do?

Answer 20

Contains light receptors some sensitive to light of different colours

Question 21

What is the optic nerve?

Answer 21

Transmits electrical impulses from retina to brain

Question 22

What happens when the eye gets exposed to bright light?

Answer 22

The radial muscle contracts and the circular muscle relaxes and the pupil decreases in size letting less light in

Question 23

What happens when the eye gets exposed to a lack of light?

Answer 23

The radial muscle relaxes and circular muscles contract and the pupil increases in size to let more light in

Question 24

What happens when we are looking at a distant object?

Answer 24

Ciliary muscles relax
Suspensory ligaments stretch thin
lens become thinner
light is refracted less

Question 25

What happens when we are looking at a near object?

Answer 25

Ciliary muscles contract
Suspensory ligaments slack
Lens becomes fatter
light is refracted more

Question 26

Which cells do we have in our eye?

Answer 26

Rods and cones but there are more rods than cones

Question 27

What does the fovea contain?

Answer 27

Only cone cells

Question 28

What is the fovea?

Answer 28

An area on the retina with lots of photosensitive cells so it has the highest visual activity

Question 29

When do rods function?

Answer 29

In low light intensities= night vision- greater sensitivity

Question 30

What do cones do?

Answer 30

They detect red blue and green.