Nervous System + Eyes

Question 1

Stimulus

Answer 1

A change in an animals surroundings

Question 2

Receptors

Answer 2

Detect changes in the environment called stimuli

Question 3

Effector (2 examples)

Answer 3

Any part of the body that produces the response

Muscles contracting
A gland releasing a hormone into blood

Question 4

Order of response to stimulus

Answer 4

Stimulus
Receptor
Coordination
Effector
Response

Question 5

Transduction

Answer 5

When energy is changed from one form to another, all receptors are transducers of energy

Question 6

Types of neurones

Answer 6

Sensory
Relay
Motor

Question 7

Nerve fibre

Answer 7

Bundles of nerve cells that pass on electrical impulses to the brain

Question 8

Sensory neurone

Answer 8

Carries impulses from the receptors to spinal cord

Question 9

Relay neurone

Answer 9

Carries impulses from the spinal cord to brain

Question 10

Motor neurone

Answer 10

Carries impulses from the brain to effector

Question 11

4 features of the nervous system

Answer 11

Fast speed of conduction
Message carried by neurones
Short duration of response
Electrical impulses

Question 12

Example of the coordinator for normal responses

Answer 12

Cerebellum in the brain

Question 13

What does the cerebellum contain and what they do (2)

Answer 13

Sensory areas for receiving a processing information

Motor areas where voluntary actions originate

Question 14

Why might some areas of the body be more sensitive than others

Answer 14

Higher density of receptors

Thickness of skin

Question 15

What are reflex actions

Answer 15

A rapid automatic response to a stimulus

Question 16

What is the nerve pathway of a rapid automatic response called

Answer 16

Reflex arc

Question 17

Where does the nerve pathway not go to for reflex actions

Answer 17

The brain

Question 18

Where is the signal processes for reflex actions

Answer 18

The spinal cord via the relay neurone

Question 19

What is the coordinator for reflex actions

Answer 19

Relay neurones in the spinal cord

Question 20

What is a synapse

Answer 20

A gap between two neurones

Question 21

How are the “messages” carried across a synapse

5 steps

Answer 21

1. Electrical impulses arrive at a synapse
2. Ends of branches of the axon secrete a chemical called a neurotransmitter
3. Neurotransmitter diffuses across synapse to the membrane of the second neurone
4. Electrical impulses start again in second cell
5. Neurotransmitter is broken down by an enzyme

Question 22

What is the difference between the speed of the diffusion of neurotransmitter and electrical impulses along a neurone

Answer 22

Diffusion of neurotransmitter is slower

Question 23

What can a reflex action in the eye control

Answer 23

The amount of light entering the eye

Question 24

Iris

Answer 24

Controls the amount of light entering the eye by changing the size of the pupil

Question 25

Which two muscles form the iris and what pattern do they form

Answer 25

Circular muscles for ring shapes Radial muscles are like spokes of a wheel

Question 26

What happens to the eye in bright light and why

Answer 26

Pupil is constructed Circular muscles contract Radial muscles relax Prevents damage to retina

Question 27

What happens to the eye in dim light and why

Answer 27

Pupil is dilated Circular muscles relax Radial muscles contract Can see a clearer image

Question 28

What does the retina contain

Answer 28

Contains light sensitive rod and cone cells which convert light energy into a nerve impulse (transduces energy)

Question 29

What are rods for (2)

Answer 29

Dim light | Black and white

Question 30

What are cones for (2)

Answer 30

Bright light | Red, green, blue

Question 31

What is accommodation

Answer 31

The lens has to change shape in order to focus on near and distant objects

Question 32

How is the lens controlled

Answer 32

By ciliary muscles and suspensory ligaments

Question 33

Ciliary muscles

Answer 33

Changes shape of the lens by altering the tension of suspensory ligaments

Question 34

What happens in the eye when focusing on a distant object

Answer 34

Lens is made flat (less convex) Ciliary muscles relax Suspensory ligaments are pulled tight

Question 35

What happens in the eye when focusing on a nearby object

Answer 35

Lens is made more rounded (convex) Ciliary muscles contract Suspensory muscles are slackened

Question 36

Cornea

Answer 36

Refracts/ bends light entering the eye

Question 37

Lens

Answer 37

Changes shape to focus on an object

Question 38

Pupil

Answer 38

Hole which allows light into the eye

Question 39

Fovea

Answer 39

Area where light is most focused, very sensitive to colour

Question 40

Optic nerve

Answer 40

Transmits nerve impulses to the brain

Question 41

Sclera

Answer 41

Outer protective layer of the eye

Question 42

Choroid

Answer 42

Contains blood vessels (and prevents light from exiting the eye?)