Response - Nervous Communication: Key Terms Flashcards

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1
Q

Central nervous system (CNS)

A

The brain and spinal cord.

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2
Q

Peripheral nervous system (PNS)

A

The nerves branching off the brain or spinal cord, allowing the CNS to communicate with the rest of the body.

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3
Q

Neurone

A

A nerve cell which is adapted to conduct action potentials.

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4
Q

Sensory (or afferent) neurones

A

Neurones which transmit nerve impulses from receptors towards the CNS.

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5
Q

Motor (or efferent) neurones

A

Neurones which transmit nerve impulses away from the CNS to an effector.

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6
Q

Relay (or intermediate) neurones

A

Neurones which transmit impulses between sensory and motor neurones.

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7
Q

Stimulus

A

A detectable change in the internal or external environment of an organism.

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8
Q

Response

A

The result of a stimulus on an organism.

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9
Q

Receptor

A

A cell adapted to detect changes in the environment.

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10
Q

Effector

A

A cell, tissue, organ or system that responds to stimulation by a nerve impulse resulting in a response.

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11
Q

Reflex arc

A

The pathway of neurones involved in a reflex.

stimulus - receptor - sensory neurone - relay neurone - motor neurone - effector - response

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12
Q

Somatic nervous system

A

A division of the motor nervous system which carries nerve impulses to body muscles and is under voluntary control.

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13
Q

Autonomic nervous system

A

A division of the motor nervous system which carries nerve impulses to glands, smooth and cardiac muscle and is not under voluntary control.

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14
Q

Sympathetic

A

An autonomic pathway which stimulates effectors and so speeds up an activity.

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15
Q

Parasympathetic

A

An autonomic pathway which inhibits effectors and so slows down an activity.

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16
Q

Axon

A

A process extending from a neurone that conducts action potentials away from the cell body.

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17
Q

Dendrons

A

Extensions of a neurone’s cell body which subdivide into smaller branched fibres, called dendrites, that transmit nerve impulses from other cells to the cell body.

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18
Q

Nerve impulse

A

A self-propagating wave of electrical disturbance that travels along the surface of an axon membrane.

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19
Q

Sodium potassium pump

A

A carrier protein which actively transports 2 potassium ions into the axon and 3 sodium ions out of the axon.

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20
Q

Resting potential

A

A potential difference of -70mV found across the plasma membrane of a neurone that is not conducting an impulse.

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21
Q

Generator potential

A

Depolarisation of the membrane of s receptor cell as a result of a stimulus.

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22
Q

Threshold value

A

The minimum level of stimulus needed to trigger an action potential: -55mV

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23
Q

Coordinator

A

The link between a sensory neurone and motor neurone in the spinal cord

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24
Q

Polarised

A

Condition used to describe the axon when the inside of an axon is negatively charged relative to the outside

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25
Q

Voltage gated channels

A

Channels in the axon membrane which change shape

and therefore open or close depending on the voltage across the membrane

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26
Q

Depolarised

A

Condition used to describe the part of the axon membrane when the inside of the membrane has a positive charge of around +40mV

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27
Q

Hyperpolarisation

A

When the inside of the axon is more negative relative to the outside than usual

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28
Q

Repolarisation

A

When the resting potential of -65mV is re-established the axon is described as this

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29
Q

Refractory period

A

Time after an action potential when it is impossible for a further action potential to be generated

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30
Q

All-or-nothing principle

A

An action potential is exactly the same size, regardless of the size of the stimulus, providing it reaches the threshold value

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31
Q

Schwann cells

A

Cells that wrap themselves around the axon many times, protecting it and providing electrical insulation

32
Q

Node of Ranvier

A

Constrictions between adjacent Schwann cells where there is no myelin sheath

33
Q

Myelin sheath

A

Covering to the axon made of the membranes of Schwann cells wrapped around a neurone

34
Q

Synapse

A

The point where the axon of one neurone connects with the dendrite of another or an effector

35
Q

Cholinergic synapse

A

A synapse which links neurones to neurones or neruones to other effector organs, in which the neurotransmitter is acetylcholine

36
Q

Adrenergic synapse

A

A synapse in which the neurotransmitter is noradrenaline

37
Q

Neurotransmitter

A

A chemical which is secreted by a neurone within the nervous system to stimulate a target cell

38
Q

Hormonal system

A

A communication system which transports hormones via the plasma to produce a slow, long-lasting response in the target cells

39
Q

Chemical mediators

A

Chemicals released by some mammalian cells which have an effect on other nearby cells

40
Q

Acetylcholine

A

A neurotransmitter used at a cholinergic synapse

41
Q

Presynaptic neurone

A

Neurone that releases the neurotransmitter from synaptic vesicles when an action potential arrives at the end of it

42
Q

Presynaptic knob

A

The swollen portion of the presynaptic neurone

43
Q

Synaptic cleft

A

The 20-30nm wide gap which is found between the presynaptic and postsynaptic neurone

44
Q

Synaptic vesicle

A

Contains the neurotransmitter in the presynaptic neurone

45
Q

ACh receptors

A

Found on the postsynaptic neurone of a cholinergic synapse where acetylcholine is the neurotransmitter

46
Q

Acetylcholine esterase enzyme

A

The enzyme which breaks down acetylcholine into choline and ethanoic acid (acetyl), removing it from the synaptic cleft

47
Q

Excitatory synapses

A

Synapses that produce new action potentials when the neurotransmitter binds with the receptor proteins

48
Q

Inhibitory synapses

A

Synapses which make it less likely that a new action potential will be created on the postsynaptic neurone

49
Q

Summation

A

Allows a build up of a neurotransmitter which enables low-frequency action potentials to trigger a new action potential in the postsynaptic neurone

50
Q

Spatial summation

A

A number of presynaptic neurones together release enough neurotransmitter to exceed the threshold value of the postsynaptic neurone, triggering a new action potential

51
Q

Temporal summation

A

One presynaptic neurone releases a neurotransmitter many times over a short period - if the concentration of neurotransmitter exceeds the threshold of the postsynaptic neurone a new action potential will be triggered

52
Q

Neuromuscular junction

A

The point at which a motor neurone meets a skeletal muscle fibre

53
Q

Skeletal muscle

A

Attached to bone and acts under voluntary, conscious control

54
Q

Smooth muscle

A

Found in the walls of blood vessels and the gut, not under conscious control

55
Q

Cardiac muscle

A

Found exclusively in the heart and not under conscious control

56
Q

Sarcolemma

A

The fine transparent tubular sheath which envelops the fibres of skeletal muscles

57
Q

Sarcoplasm

A

The cytoplasm and nuclei which muscle fibres share, mostly found around the circumference of the fibre

58
Q

Sarcoplasmic reticulum

A

A large vesicle in a contracting muscle cell which contains the Ca2+ ions to allow to troponin to bind and filaments to slide

59
Q

Multi-nucleated

A

Contains more than one nucleus

60
Q

Myofibrils (muscle fibres)

A

A microscopic muscle fibre containing sarcoplasm and showing striped I and A bands of actin and myosin

61
Q

Actin

A

A globular protein whose 2 molecules are arranged into long chains that are twisted around one another to form a helical strand

62
Q

Myosin

A

Made of a fibrous protein arranged into a filament made up of several hundred molecules and a globular protein formed into two bulbous structures at one end

63
Q

Tropomyosin

A

Forms long thin threads that are wound around actin filaments

64
Q

A band

A

Ansiotropic bands (dark) where thick and thin filaments overlap

65
Q

I band

A

Isotropi bands (light) where thick and thin filaments do not overlap

66
Q

H zone

A

The centre of each A-band where there is a lighter-coloured region

67
Q

Z line

A

The centre of each I-band

68
Q

Sarcomere

A

The distance between two adjacent Z-lines

69
Q

Contraction

A

The process a muscle undergoes where the I band becomes narrower, the Z-lines move closer and the H-zone becomes narrower

70
Q

Globular heads

A

Part of myosin that attaches to binding site on actin filaments

71
Q

Myosin binding site

A

Found on the actin molecule and can be blocked by tropomyosin

72
Q

Ca2+

A

Causes tropomyosin molecule to change shape and pull away from the binding sites on the actin molecule

73
Q

Phosphocreatine

A

Found in muscle that provides a reverse supply of phosphate, which can immediately recombine with ADP to re-form ATP

74
Q

Slow twitch

A

Muscle fibres adapted for aerobic respiration and endurance work. Contract more slowly and provide less powerful contractions but can contract for long periods.

75
Q

Fast twitch

A

Muscle fibres adapted for anaerobic respiration and intense exercise. Contract more rapidly and produce powerful contractions but only for a short periods.

76
Q

Myoglobin

A

A red protein containing haem, which carries and stores oxygen in muscle cells.

77
Q

Sliding filament theory

A

A process which explains how muscles contract, involving actin and myosin molecules sliding past each other