Nervous System + Eyes Flashcards

1
Q

Stimulus

A

A change in an animals surroundings

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2
Q

Receptors

A

Detect changes in the environment called stimuli

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3
Q

Effector (2 examples)

A

Any part of the body that produces the response

Muscles contracting
A gland releasing a hormone into blood

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4
Q

Order of response to stimulus

A
Stimulus
Receptor
Coordination
Effector
Response
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5
Q

Transduction

A

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

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6
Q

Types of neurones

A

Sensory
Relay
Motor

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7
Q

Nerve fibre

A

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

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8
Q

Sensory neurone

A

Carries impulses from the receptors to spinal cord

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9
Q

Relay neurone

A

Carries impulses from the spinal cord to brain

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10
Q

Motor neurone

A

Carries impulses from the brain to effector

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11
Q

4 features of the nervous system

A

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

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12
Q

Example of the coordinator for normal responses

A

Cerebellum in the brain

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13
Q

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

A

Sensory areas for receiving a processing information

Motor areas where voluntary actions originate

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14
Q

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

A

Higher density of receptors

Thickness of skin

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15
Q

What are reflex actions

A

A rapid automatic response to a stimulus

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16
Q

What is the nerve pathway of a rapid automatic response called

A

Reflex arc

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17
Q

Where does the nerve pathway not go to for reflex actions

A

The brain

18
Q

Where is the signal processes for reflex actions

A

The spinal cord via the relay neurone

19
Q

What is the coordinator for reflex actions

A

Relay neurones in the spinal cord

20
Q

What is a synapse

A

A gap between two neurones

21
Q

How are the “messages” carried across a synapse

5 steps

A
  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
22
Q

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

A

Diffusion of neurotransmitter is slower

23
Q

What can a reflex action in the eye control

A

The amount of light entering the eye

24
Q

Iris

A

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

25
Q

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

A

Circular muscles for ring shapes

Radial muscles are like spokes of a wheel

26
Q

What happens to the eye in bright light and why

A

Pupil is constructed
Circular muscles contract
Radial muscles relax

Prevents damage to retina

27
Q

What happens to the eye in dim light and why

A

Pupil is dilated
Circular muscles relax
Radial muscles contract

Can see a clearer image

28
Q

What does the retina contain

A

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

29
Q

What are rods for (2)

A

Dim light

Black and white

30
Q

What are cones for (2)

A

Bright light

Red, green, blue

31
Q

What is accommodation

A

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

32
Q

How is the lens controlled

A

By ciliary muscles and suspensory ligaments

33
Q

Ciliary muscles

A

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

34
Q

What happens in the eye when focusing on a distant object

A

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

35
Q

What happens in the eye when focusing on a nearby object

A

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

36
Q

Cornea

A

Refracts/ bends light entering the eye

37
Q

Lens

A

Changes shape to focus on an object

38
Q

Pupil

A

Hole which allows light into the eye

39
Q

Fovea

A

Area where light is most focused, very sensitive to colour

40
Q

Optic nerve

A

Transmits nerve impulses to the brain

41
Q

Sclera

A

Outer protective layer of the eye

42
Q

Choroid

A

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