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Biology Unit 3 > 3.8 The Nervous System > Flashcards

3.8 The Nervous System Flashcards

1
Q

What is a stimulus ?

A

A detectable change in the internal or external environment of an organism that produces a response

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2
Q

What is a receptor ?

A

A specialised structure that detects a specific type of stimulus

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3
Q

What is an effector ?

A

An organ, tissue or cell that produces a response to a stimulus and carries out the response

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4
Q

What is a response ?

A

Detects the change causing a stimulus

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5
Q

What is a neurone ?

A

Specialised cells adapted to rapidly carry nervous impulse from 1 part of the body to another

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6
Q

What is an impulse ?

A

Pulse of electrical energy sent along the axon

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7
Q

What is the purpose of the nervous system ?

A

To detect changes or stimuli inside the body and in the environment to process and store information and initiate responses

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8
Q

What are the 2 parts of the nervous system ?

A

Central and peripheral

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9
Q

What makes up the central nervous system ?

A

Brain and spinal cord

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10
Q

What is the function of the central nervous system ?

A

Process information from a stimulus

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11
Q

What does the central nervous system contain ?

A

Grey matter
White matter
Relay neurones

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12
Q

What is white matter made up of ?

A

Nerve fibres and myelin

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13
Q

What is grey matter made up of ?

A

Nerve fibres of relay neurones
Relay and motor neurone cell bodies

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14
Q

What is the 2 parts of the peripheral nervous system ?

A

Autonomous and somatic

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15
Q

What is the function of the autonomous nervous system ?

A

Interacts with internal organs and glands providing unconscious control of the functions of internal organs

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16
Q

What is the function of somatic nervous system ?

A

Interacts with sensory organs and voluntary muscle allowing impulses to be carried from receptors to the central nervous system then to effectors

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17
Q

What neurones does the somatic nervous system contain ?

A

Sensory and motor

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18
Q

What are the 8 senses ?

A

Sight
Hearing
Touch
Pain
Smell
Taste
Temperature
Balance

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19
Q

What are the 2 types of stimuli ?

A

Internal and external

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20
Q

What is an internal stimuli ?

A

Changes within an organism often signalling alteration in its psychological state

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21
Q

What is an external stimuli ?

A

Environmental factors influencing an organism externally

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22
Q

What are the 2 sides of a spinal cord called ?

A

Dorsal and ventral

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23
Q

What is a hydra made up of ?

A

A simple nervous system called a nerve net

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24
Q

What makes up a neurone network ?

A

Sensory and ganglia cells

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25
Q

What is the function of ganglion cells ?

A

Provide connections in several directions

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26
Q

What is the function of sensory cells ?

A

Detect stimuli

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27
Q

What are the features of a Hydra ?

A

No brain
Slow conduction speed
Respond to limited number of stimuli due to have very few effectors

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28
Q

What is a reflex ?

A

An inborn response to a stimulus

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29
Q

What are the features of a reflex ?

A

Rapid
Automatic
Preventive
Protective

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30
Q

What is a reflex arc ?

A

A rapid and automatic response resulting from nervous impulses initiated by a stimulus

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31
Q

What are the stages of a reflex arc ?

A

1) Stimulus
2)Sensory Receptor
3) Sensory Neurone
4) Central Nervous system
5) Motor Neurone
6) Reponse
7) Feedback

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32
Q

What is a neurone ?

A

Specialised cells adapted to carry nervous impulses from 1 part of the body to another

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33
Q

What are the 3 types of neurones ?

A

Sensory
Relay
Motor

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34
Q

What is the function of a sensory neurone ?

A

Carries impulses from sense receptors to the central nervous system

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35
Q

What is the function of a relay neurone ?

A

Receive impulses from sensory neurone and transmit to motor neurone

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36
Q

What is the function of a motor neurone ?

A

Carry impulses from the central nervous system to the effector

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37
Q

What is the function of dendrites ?

A

Receive and carry information to cell body

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38
Q

What is the function of the cell body of a motor neurone ?

A

Carry out normal cell functions. Contains many lysosomes and mitochondria

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39
Q

What is the function of the nucleus in a motor neurone ?

A

Control cell function

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40
Q

What is the function of the axon in a motor neurone ?

A

Carry information from the cell body to the axon endings

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41
Q

What is the function of axon endings in a motor neurone ?

A

Transmit impulse to another neurone or affector

42
Q

What is the function of the Nodes of Ranvier in a motor neurone ?

A

Unmeylinated sections of the neurone, the impulse leaps from 1 node to the other

43
Q

What is the function of the myelin sheath in a motor neurone ?

A

Provide electrical insulation to speed up the conduction of an electrical impulse

44
Q

What is the function of a Schwann cell ?

A

Forms the myelin sheath

45
Q

What is a resting potential ?

A

The action of sodium potassium pumps and potassium ion channels leads to a potential difference across the neurone membrane. No nervous impulse is conducted

46
Q

What is potential difference ?

A

Difference in electrical charge between 2 areas

47
Q

What is an ion ?

A

Electrically charge particles due to the loss or gain of an electron

48
Q

What is a cation ?

A

Positively charged ion

49
Q

What is an anion ?

A

Negatively charged ion

50
Q

What is the definition of polarised ?

A

Where there is a potential difference across a membrane

51
Q

What is the definition of depolarised ?

A

When a cell membrane has a temporary reversal of potential

52
Q

What is a nervous impulse ?

A

Transmission of a change in potential along a nerve fibre associated with movement of sodium ions

53
Q

What is an action potential ?

A

A rapid rise and fall of electrical potential across a membrane of nerve cell as a nervous impulse passes

54
Q

What is an excitable cell ?

A

One in which the potential across a cell can be altered

55
Q

What is impulse propagation?

A

An action potential which begins at one end and is propagated along the axon

56
Q

Which membrane is more negative in resting potential ?

57
Q

What is the difference in mV between the inside and outside membrane

A

Inside is more negative by -70

58
Q

How are resting potentials maintained ?

A

Sodium potassium pumps
Voltage gated sodium channels
Large protein anions

59
Q

What are the 7 stages on an action potential graph ?

A

Stimulus
Threshold
Depolarisation
Action potential
Depolarisation
Hyperpolarisation
Resting state

60
Q

Why can’t an impulse travel backwards ?

A

Due to the absolute refractory period
Voltage gated sodium channels are temporarily inactivated and don’t reopen until new resting potential has been established preventing another action potential

61
Q

What is threshold potential ?

A

If the intensity of a stimulus exceeds -55mV threshold an action potential is initiated

62
Q

What is saltatory conduction ?

A

The process of an action potential jumping from node to node

63
Q

What is a localised current ?

A

Current occurring in 1 part of an axon

64
Q

What is hyperpolarisation ?

A

Movement of a cells membrane potential to a more negative value. A hyperpolarised neurone is less likely to fire an action potential

65
Q

What is a refractory period ?

A

A period of time after an action potential in which further action potentials are impossible or less likely

66
Q

What are voltage gated sodium channels ?

A

A membrane protein channel that is opened at a set voltage

67
Q

What are the 2 types of refractory periods ?

A

Absolute and relative

68
Q

What happens in the absolute refractory period ?

A

No new action potentials are initiated
Voltage gated sodium channels are inactivated
Lasts around 1ms

69
Q

What happens in the relative refractory period ?

A

Occurs during hyperpolarisation
Action potential only occurs is impulse is strong enough
Lasts 4 to 10 ms

70
Q

What causes the relative refractory period ?

A

Outward diffusion of potassium ions making the threshold harder to reach

71
Q

What are the factors that affect the speed of conduction of a nervous impulse ?

A

Temperature
Axon diameter
Myelination

72
Q

How does temperature affect speed of conduction of nervous impulses ?

A

Higher temperatures = Increased kinetic energy =Ions move faster

73
Q

How does axon diameter affect speed of conduction of nervous impulses ?

A

Greater the diameter the faster the conduction as there’s more ion channels so more sodium can get in

74
Q

How does myelin affect speed of conduction of nervous impulses ?

A

Acts as an electrical insulator meaning less ATP is needed to transfer action potentials along an axon, dramatically increases speed of propagation

75
Q

What is the function of a synapse ?

A

Junction between neurones
Send nervous impulses between neurones in 1 direction

76
Q

What are the 2 types of synapses ?

A

Electrical and chemical

77
Q

What is an electrical synapse features ?

A

Directly transmits impulse from 1 neurone to the next

78
Q

What are the features of a chemical synapse ?

A

Impulse is transmitted by a neurotransmitter
Chemical is secreted by exocytosis into pre synaptic membrane in response to an action potential
Diffuses across synaptic cleft
Binds to receptors on post synaptic membrane

79
Q

What does an action potential cause in synaptic transmission ?

A

Voltage gated calcium channels to open

80
Q

How is the sodium channel opened in synaptic transmission ?

A

Receptor protein changes shape on binding making the channel open

81
Q

What causes a wave of depolarisation to be sent along the membrane in synaptic transmission ?

A

NA+ ions diffusing into post synaptic membrane

82
Q

What causes the post synaptic membrane to depolarise in synaptic transmission ?

A

Threshold being reached

83
Q

What is acetylcholine broken down by ?

A

Acetylcholinesterase

84
Q

What is acetylcholine broken down into ?

A

Acetate and choline

85
Q

What happens if acetylcholine remains in the synaptic cleft ?

A

Continuous initiation of impulses and a potential merging of impulses

86
Q

What are drugs ?

A

A medicine or other substance which has a psychological affect when ingested or introduced into the body

87
Q

What do drugs affect ?

A

The actions of neurotransmitters and inhibit breakdown of a neurotransmitter

88
Q

Name 4 types of drugs ?

A

Organophosphates
Sedatives
Stimulants
Psychoactive drugs

89
Q

What are the effects of sedatives on the nervous system ?

A

Inhibit
Create fewer action potentials in the post synaptic neurone

90
Q

Name a type of sedative

91
Q

What are the affects of stimulants on the nervous system ?

A

Cause more action potentials in the post synaptic membrane

92
Q

Name a type of stimulant

A

Amphetamines

93
Q

How do organophosphates affect synapses ?

A

Prevent breakdown of acetylcholine so it isn’t hydrolysed and remains in the synaptic cleft meaning the post synaptic neurone repeatedly fires

94
Q

Name 3 organophosphates

A

Insecticides
Herbicides
Nerve gases

95
Q

What are psychoactive drugs?

A

Drugs that act on the central nervous system affecting various neurotransmitters and their receptors

96
Q

What are the 2 types of psychoactive drugs ?

A

Recreation and medicinal

97
Q

Name 3 medicinal psychoactive drugs

A

Ritalin
Prozac
Paxil

98
Q

Name 3 recreational psychoactive drugs

A

Cocaine
Nicotine
Alcohol

99
Q

What are the effects of nicotine on the body ?

A

Mimics the action of the neurotransmitter and binds to receptors on the post synaptic membrane

100
Q

How does caffeine work as a stimulant ?

A

Increases metabolic rate in pre synaptic cells so ATP synthesis increases which causes neurotransmitter synthesis to also increase

Biology Unit 3 (8 decks)

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