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Biology Unit 3 > 3.8 The Nervous System > Flashcards

3.8 The Nervous System Flashcards

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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
What is the function of ganglion cells ?
Provide connections in several directions
26
What is the function of sensory cells ?
Detect stimuli
27
What are the features of a Hydra ?
No brain Slow conduction speed Respond to limited number of stimuli due to have very few effectors
28
What is a reflex ?
An inborn response to a stimulus
29
What are the features of a reflex ?
Rapid Automatic Preventive Protective
30
What is a reflex arc ?
A rapid and automatic response resulting from nervous impulses initiated by a stimulus
31
What are the stages of a reflex arc ?
1) Stimulus 2)Sensory Receptor 3) Sensory Neurone 4) Central Nervous system 5) Motor Neurone 6) Reponse 7) Feedback
32
What is a neurone ?
Specialised cells adapted to carry nervous impulses from 1 part of the body to another
33
What are the 3 types of neurones ?
Sensory Relay Motor
34
What is the function of a sensory neurone ?
Carries impulses from sense receptors to the central nervous system
35
What is the function of a relay neurone ?
Receive impulses from sensory neurone and transmit to motor neurone
36
What is the function of a motor neurone ?
Carry impulses from the central nervous system to the effector
37
What is the function of dendrites ?
Receive and carry information to cell body
38
What is the function of the cell body of a motor neurone ?
Carry out normal cell functions. Contains many lysosomes and mitochondria
39
What is the function of the nucleus in a motor neurone ?
Control cell function
40
What is the function of the axon in a motor neurone ?
Carry information from the cell body to the axon endings
41
What is the function of axon endings in a motor neurone ?
Transmit impulse to another neurone or affector
42
What is the function of the Nodes of Ranvier in a motor neurone ?
Unmeylinated sections of the neurone, the impulse leaps from 1 node to the other
43
What is the function of the myelin sheath in a motor neurone ?
Provide electrical insulation to speed up the conduction of an electrical impulse
44
What is the function of a Schwann cell ?
Forms the myelin sheath
45
What is a resting potential ?
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
What is potential difference ?
Difference in electrical charge between 2 areas
47
What is an ion ?
Electrically charge particles due to the loss or gain of an electron
48
What is a cation ?
Positively charged ion
49
What is an anion ?
Negatively charged ion
50
What is the definition of polarised ?
Where there is a potential difference across a membrane
51
What is the definition of depolarised ?
When a cell membrane has a temporary reversal of potential
52
What is a nervous impulse ?
Transmission of a change in potential along a nerve fibre associated with movement of sodium ions
53
What is an action potential ?
A rapid rise and fall of electrical potential across a membrane of nerve cell as a nervous impulse passes
54
What is an excitable cell ?
One in which the potential across a cell can be altered
55
What is impulse propagation?
An action potential which begins at one end and is propagated along the axon
56
Which membrane is more negative in resting potential ?
Inside
57
What is the difference in mV between the inside and outside membrane
Inside is more negative by -70
58
How are resting potentials maintained ?
Sodium potassium pumps Voltage gated sodium channels Large protein anions
59
What are the 7 stages on an action potential graph ?
Stimulus Threshold Depolarisation Action potential Depolarisation Hyperpolarisation Resting state
60
Why can’t an impulse travel backwards ?
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
What is threshold potential ?
If the intensity of a stimulus exceeds -55mV threshold an action potential is initiated
62
What is saltatory conduction ?
The process of an action potential jumping from node to node
63
What is a localised current ?
Current occurring in 1 part of an axon
64
What is hyperpolarisation ?
Movement of a cells membrane potential to a more negative value. A hyperpolarised neurone is less likely to fire an action potential
65
What is a refractory period ?
A period of time after an action potential in which further action potentials are impossible or less likely
66
What are voltage gated sodium channels ?
A membrane protein channel that is opened at a set voltage
67
What are the 2 types of refractory periods ?
Absolute and relative
68
What happens in the absolute refractory period ?
No new action potentials are initiated Voltage gated sodium channels are inactivated Lasts around 1ms
69
What happens in the relative refractory period ?
Occurs during hyperpolarisation Action potential only occurs is impulse is strong enough Lasts 4 to 10 ms
70
What causes the relative refractory period ?
Outward diffusion of potassium ions making the threshold harder to reach
71
What are the factors that affect the speed of conduction of a nervous impulse ?
Temperature Axon diameter Myelination
72
How does temperature affect speed of conduction of nervous impulses ?
Higher temperatures = Increased kinetic energy =Ions move faster
73
How does axon diameter affect speed of conduction of nervous impulses ?
Greater the diameter the faster the conduction as there’s more ion channels so more sodium can get in
74
How does myelin affect speed of conduction of nervous impulses ?
Acts as an electrical insulator meaning less ATP is needed to transfer action potentials along an axon, dramatically increases speed of propagation
75
What is the function of a synapse ?
Junction between neurones Send nervous impulses between neurones in 1 direction
76
What are the 2 types of synapses ?
Electrical and chemical
77
What is an electrical synapse features ?
Directly transmits impulse from 1 neurone to the next
78
What are the features of a chemical synapse ?
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
What does an action potential cause in synaptic transmission ?
Voltage gated calcium channels to open
80
How is the sodium channel opened in synaptic transmission ?
Receptor protein changes shape on binding making the channel open
81
What causes a wave of depolarisation to be sent along the membrane in synaptic transmission ?
NA+ ions diffusing into post synaptic membrane
82
What causes the post synaptic membrane to depolarise in synaptic transmission ?
Threshold being reached
83
What is acetylcholine broken down by ?
Acetylcholinesterase
84
What is acetylcholine broken down into ?
Acetate and choline
85
What happens if acetylcholine remains in the synaptic cleft ?
Continuous initiation of impulses and a potential merging of impulses
86
What are drugs ?
A medicine or other substance which has a psychological affect when ingested or introduced into the body
87
What do drugs affect ?
The actions of neurotransmitters and inhibit breakdown of a neurotransmitter
88
Name 4 types of drugs ?
Organophosphates Sedatives Stimulants Psychoactive drugs
89
What are the effects of sedatives on the nervous system ?
Inhibit Create fewer action potentials in the post synaptic neurone
90
Name a type of sedative
Alcohol
91
What are the affects of stimulants on the nervous system ?
Cause more action potentials in the post synaptic membrane
92
Name a type of stimulant
Amphetamines
93
How do organophosphates affect synapses ?
Prevent breakdown of acetylcholine so it isn’t hydrolysed and remains in the synaptic cleft meaning the post synaptic neurone repeatedly fires
94
Name 3 organophosphates
Insecticides Herbicides Nerve gases
95
What are psychoactive drugs?
Drugs that act on the central nervous system affecting various neurotransmitters and their receptors
96
What are the 2 types of psychoactive drugs ?
Recreation and medicinal
97
Name 3 medicinal psychoactive drugs
Ritalin Prozac Paxil
98
Name 3 recreational psychoactive drugs
Cocaine Nicotine Alcohol
99
What are the effects of nicotine on the body ?
Mimics the action of the neurotransmitter and binds to receptors on the post synaptic membrane
100
How does caffeine work as a stimulant ?
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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