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Biology IGCSE CIE Extended > The Nervous System > Flashcards

The Nervous System Flashcards

1
Q

What does the nervous system enable humans to do?

A

Enables humans to react to their surroundings and coordinate their behavior

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2
Q

What is it made out of?

A

A network of nerves

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3
Q

What do nerves do?

A

Transmit electrical impulses between the brain, spinal cord, and the rest of the body.

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4
Q

What is the role of nerves?

A

to transmit electrical impulses

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5
Q

What is the CNS (central nervous system) made up of?

A

The brain and the spinal cord

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6
Q

What helps the CNS carry out its responses?

A

Coordinates responses via:

  • receptors
  • sensory neurones
  • motor neurones
  • effectors
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7
Q

What does the PERIPHERAL nervous system consist of?

A

Consists of neurones that travel to and from the CNS.

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8
Q

What is the peripheral nervous system’s role?

A

Connects the CNS to the body

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9
Q

What is a nerve?

A

A bundle of many neurones

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10
Q

What is a neurone?

A

An individual nerve cell

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11
Q

What do neurones do?

A

Neurones carry electrical impulses between receptors, the CNS and effectors

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12
Q

What do nerves do?

A

Nerves carry electrical impulses from the CNS to the rest of the body

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13
Q

What do receptors do?

A

detect change/ stimuli

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14
Q

What does the CNS do?

A

Coordinate a response

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15
Q

What do effectors do?

A

Carry out a response

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16
Q

What are effectors and why are they called that?

A

Often glands or muscles

Called that because they go into action when they recieve nerve impulses of hormones.

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17
Q

What are nerve impulses from sense organs to the CNS called?

A

sensory impulses

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18
Q

What are nerve impulses from the CNS to the effectors called?

A

motor impulses

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19
Q

How does the nervous system act as a COORDINATOR?

A

Acts as a coordinator by directing responses to stimuli such as changes in body conditions

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20
Q

How do sensory receptors help to coordinate a response?

A

Sensory receptors, located in sense organs, stimulate sensory neurones.

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21
Q

What do relay neurones do?

A

Relay neurones in CNS stimulate motor neurones

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22
Q

What are examples of responses that effectors can carry out?

A
  • muscle contraction

- hormone secretion

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23
Q

What is the junction between 2 neurones called?

A

A synapse / synaptic cleft

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24
Q

How do electrical impulses pass between neurones?

A

When an electrical impulse reaches the end of the first neurone, it triggers the release of a chemical. This chemical is called NEUROTRANSIMITTER

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25
Q

How does the neurotransmitter travel?

A

Diffuses across the gap

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26
Q

Does the process of the electrical impulse travelling over the synapse slow down the speed of nerve impulses?

A

Yes

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27
Q

Do synapses control the direction of impulses? If so, how?

A

Yes
- neurotransmitter substances are synthesised on only one side of the nerve impulse, while receptor molecules are only present on one side

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28
Q

How does heroin interact with receptor molecules at synapses?

A

Stimulates receptor molecules in synapses in the brain, triggering the release of dopamine

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29
Q

How do spider toxin and the toxin released by tetanus affect the nervous system?

A

Breaks down vesicles, releasing mass amounts of transmitter substance and disrupting normal synaptic function.

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30
Q

What is a reflex?

A

A very fast, automatic response to a stimulus that does not involve direct coordination by the concious part of the brain. They are INVOLUNTARY.

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31
Q

What are reflexes coordinated by?

A

Reflex arcs

32
Q

What does a reflex arc consist of?

A

Consists of an electrical impulse being directly transmitted from a sensory neuron, via a relay neuron, to a motor neuron, to stimulate a rapid response.

33
Q

Why are reflexes so fast in bringing about a response?

A

This is because when the electrical impulse reaches the CNS, it often only passes through the spinal cord, and not the brain.

34
Q

How is the brain informed that a reflex reaction has occured?

A

If the reflex signal does not initiialy pass through the brain, a seperate impulse can be sent from the spinal cord to the concious part of the brain.

35
Q

Why are reflexes important?

A

Help protect the body from danger

36
Q

What is reaction time?

A

Time taken for a response to occur in reaction to a stimulus

37
Q

What are the 3 types of neurones?

A

Motor, Sensory, Relay

38
Q

Where do motor neurones carry signals from and to?

A

From the CNS to effectors

39
Q

Where do sensory neurones carry signals from and to?

A

From the receptors / sense organs to the CNS

40
Q

Where do relay neurones carry signals from and to?

A

Connect motor and sensory neurones

41
Q

Where are the cell bodies of the neurones mainly located?

A

brain or spinal cord

42
Q

What types of neurones can a nerve contain?

A

A combination of sensory and motor nerve fibres (axons) in order to carry many different impulses

43
Q

What is an impulse?

A

A series of electrical pulses which travel down the axon

44
Q

At what speed does a nerve impulse travel?

45
Q

Are all nerve impulses similar?

46
Q

What is a spinal reflex?

Examples

A

A reflex that uses relay neurones in the spine cord

- withdrawing the hand from a hot object

47
Q

Examples of reflexes that take place in the head?

location: not coordinated by brain

A

Iris reflex
Blinking
Coughing

48
Q

Synapse definition

A

A junction between 2 neurones

49
Q

What is a volunatry action?

A

One which requires a concious decision by the brain

  • Unlike a reflex action, it does not happen automatically
  • choice in selection of the response
50
Q

What is the main function of the brain during voluntary actions?

A

To coordinate the actions so that they happen in the right sequence and at the right time and place.

51
Q

Definition of a sense organ?

Example

A

Sense organs are groups of sensory cells, responding to specific stimuli, such as light, sound, touch, temperature and chemicals.
e.g eye / ear

52
Q

Definition of stimulus

A

A change in the enivronment (light, tempertaure, pressure) which produces a reaction in a living organism.

53
Q

list 5 sense organs and the stimuli they respond to

A
  1. ear - sound, body movement (balance)
  2. eye - light
  3. nose - chemicals (smells)
  4. tongue - chemicals (taste)
  5. skin - temperature, pressure, touch, pain
54
Q

What is the special property of sensory cells and organs?

A

They are able to convert one form of energy into another

e.g eyes can convert light energy into electrical energy (of nerve impulse)

55
Q

Describe the reflex arc of coughing

A

STIMULUS - Particles making contact with the lining of the respiratory tree
RESPONSE - Violent contraction of the diaphragm and internal intercostal muscles

56
Q

What is the survival value of coughing?

A

Prevents lungs being damaged or infected, so that gas exchange remains efficient

57
Q

What is the survival value of the knee-jerk reflex?

A

The leg can support the body’s wait during walking

58
Q

Describe the reflex arc of swallowing

A

STIMULUS - Food particles making contact with the back of the throat
RESPONSE - Contraction of the muscle of the epiglottis, which closes off the entrance to the trachea

59
Q

What is the survival value of swallowing?

A

Prevents food entering the respiratory pathway so that lungs are not damaged

60
Q

What does the white matter in the spine contain?

A

Contains the nerve fibres

61
Q

What does the grey matter in the spine contain?

A

Contains cell bodies of the motor neurones

62
Q

Can impulses travel both ways?

A

No

- synapses act as valves, forcing impulses to travel 1 way

63
Q

What is intergration?

A

When the CNS processes information from receptors and passes instructions to effectors to tell the organism how to respond

64
Q

What is a cranial reflex?

A

Reflexes that use the brain as a relay centre without conscious involvement.

65
Q

Where do learned reflexes take place?

A

In the lower regions of the brain

66
Q

How are learned reflexes activated?

A

need a stimulus from a higher region, but once started always lead to the same response

67
Q

What is the system called that controls the reflexes which help keep a constant internal environment in the body ?
Examples of such reflexes

A

Autonomic nervous system

e.g breathing, heart beat, peristalsis

68
Q

How can the brain communicate with the other parts of the body?

A

Via the spinal cord

69
Q

definition of involuntary action

A

Does not involve any consious decision by the brain

  • organism has no choice
  • response automatically follows the stimulus
70
Q

How are learned reflexes formed?

A

Each time a particular stimulus leads to a certain response, that impulse passes along the same route
e.g talking, cycling

71
Q

What is a transducer?

A

Something which can convert one type of energy into another

- sense organs convert energy

72
Q

What are the 4 types of receptors?

A

Photoreceptor - light
Chemoreceptor - chemicals
Thermoreceptor - changes in temp.
Mechanoreceptor - mechanical changes such as changes in length

73
Q

Where can you find them?

A

p - rod cells in retina of eyes
c - taste buds
t - t in skin
m - hair cells in ear (hearing and balance)

74
Q

What is a conditioned reflex?

A

Learned reflexes in which the final response has no natural relationship to the stimulus

75
Q

Can conditioned reflexes be unlearnt? How?

A

Yes

- if the unnatural stimulus is not repeated with the natural one

Biology IGCSE CIE Extended (22 decks)

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