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A Level Biology > Response - Nervous Communication: Key Terms > Flashcards

Response - Nervous Communication: Key Terms Flashcards

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
Voltage gated channels
Channels in the axon membrane which change shape | and therefore open or close depending on the voltage across the membrane
26
Depolarised
Condition used to describe the part of the axon membrane when the inside of the membrane has a positive charge of around +40mV
27
Hyperpolarisation
When the inside of the axon is more negative relative to the outside than usual
28
Repolarisation
When the resting potential of -65mV is re-established the axon is described as this
29
Refractory period
Time after an action potential when it is impossible for a further action potential to be generated
30
All-or-nothing principle
An action potential is exactly the same size, regardless of the size of the stimulus, providing it reaches the threshold value
31
Schwann cells
Cells that wrap themselves around the axon many times, protecting it and providing electrical insulation
32
Node of Ranvier
Constrictions between adjacent Schwann cells where there is no myelin sheath
33
Myelin sheath
Covering to the axon made of the membranes of Schwann cells wrapped around a neurone
34
Synapse
The point where the axon of one neurone connects with the dendrite of another or an effector
35
Cholinergic synapse
A synapse which links neurones to neurones or neruones to other effector organs, in which the neurotransmitter is acetylcholine
36
Adrenergic synapse
A synapse in which the neurotransmitter is noradrenaline
37
Neurotransmitter
A chemical which is secreted by a neurone within the nervous system to stimulate a target cell
38
Hormonal system
A communication system which transports hormones via the plasma to produce a slow, long-lasting response in the target cells
39
Chemical mediators
Chemicals released by some mammalian cells which have an effect on other nearby cells
40
Acetylcholine
A neurotransmitter used at a cholinergic synapse
41
Presynaptic neurone
Neurone that releases the neurotransmitter from synaptic vesicles when an action potential arrives at the end of it
42
Presynaptic knob
The swollen portion of the presynaptic neurone
43
Synaptic cleft
The 20-30nm wide gap which is found between the presynaptic and postsynaptic neurone
44
Synaptic vesicle
Contains the neurotransmitter in the presynaptic neurone
45
ACh receptors
Found on the postsynaptic neurone of a cholinergic synapse where acetylcholine is the neurotransmitter
46
Acetylcholine esterase enzyme
The enzyme which breaks down acetylcholine into choline and ethanoic acid (acetyl), removing it from the synaptic cleft
47
Excitatory synapses
Synapses that produce new action potentials when the neurotransmitter binds with the receptor proteins
48
Inhibitory synapses
Synapses which make it less likely that a new action potential will be created on the postsynaptic neurone
49
Summation
Allows a build up of a neurotransmitter which enables low-frequency action potentials to trigger a new action potential in the postsynaptic neurone
50
Spatial summation
A number of presynaptic neurones together release enough neurotransmitter to exceed the threshold value of the postsynaptic neurone, triggering a new action potential
51
Temporal summation
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
Neuromuscular junction
The point at which a motor neurone meets a skeletal muscle fibre
53
Skeletal muscle
Attached to bone and acts under voluntary, conscious control
54
Smooth muscle
Found in the walls of blood vessels and the gut, not under conscious control
55
Cardiac muscle
Found exclusively in the heart and not under conscious control
56
Sarcolemma
The fine transparent tubular sheath which envelops the fibres of skeletal muscles
57
Sarcoplasm
The cytoplasm and nuclei which muscle fibres share, mostly found around the circumference of the fibre
58
Sarcoplasmic reticulum
A large vesicle in a contracting muscle cell which contains the Ca2+ ions to allow to troponin to bind and filaments to slide
59
Multi-nucleated
Contains more than one nucleus
60
Myofibrils (muscle fibres)
A microscopic muscle fibre containing sarcoplasm and showing striped I and A bands of actin and myosin
61
Actin
A globular protein whose 2 molecules are arranged into long chains that are twisted around one another to form a helical strand
62
Myosin
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
Tropomyosin
Forms long thin threads that are wound around actin filaments
64
A band
Ansiotropic bands (dark) where thick and thin filaments overlap
65
I band
Isotropi bands (light) where thick and thin filaments do not overlap
66
H zone
The centre of each A-band where there is a lighter-coloured region
67
Z line
The centre of each I-band
68
Sarcomere
The distance between two adjacent Z-lines
69
Contraction
The process a muscle undergoes where the I band becomes narrower, the Z-lines move closer and the H-zone becomes narrower
70
Globular heads
Part of myosin that attaches to binding site on actin filaments
71
Myosin binding site
Found on the actin molecule and can be blocked by tropomyosin
72
Ca2+
Causes tropomyosin molecule to change shape and pull away from the binding sites on the actin molecule
73
Phosphocreatine
Found in muscle that provides a reverse supply of phosphate, which can immediately recombine with ADP to re-form ATP
74
Slow twitch
Muscle fibres adapted for aerobic respiration and endurance work. Contract more slowly and provide less powerful contractions but can contract for long periods.
75
Fast twitch
Muscle fibres adapted for anaerobic respiration and intense exercise. Contract more rapidly and produce powerful contractions but only for a short periods.
76
Myoglobin
A red protein containing haem, which carries and stores oxygen in muscle cells.
77
Sliding filament theory
A process which explains how muscles contract, involving actin and myosin molecules sliding past each other

A Level Biology (75 decks)

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