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A Level Biology > Module 5.1.3 Neuronal Communication > Flashcards

Module 5.1.3 Neuronal Communication Flashcards

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1
Q

What is the difference between a nerve & a neurone?

A

Nerve - tissue
Neurone - cell

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2
Q

What is the function of a neurone?

A

To transmit/carry electrical impulses

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3
Q

What is the structure of a neuron?

A

Soma/cell body
Dendrite
Dendron
Myelin sheath
Schwann cell
Nodes of Ranvier
Axon
Axon terminals

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4
Q

What is the function of the soma?

A

Contains the nucleus & is part of the dendrites in motor & relay neurones

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5
Q

What is the function of the dendrite?

A

Recieves the stimulus via receptors & carries it to the cell body via the dendron in sensory neurons

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6
Q

What is the function of the dendron?

A

Transmit the electrical impulse

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7
Q

Which neurone is the dendron present in?

A

Sensory

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8
Q

What is the function of the myelin sheath?

A

Protects & insulates the axon to speed up the electrical impulse

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9
Q

What is the function of the Schwann cell?

A

Forms layers of myelin around the axon for insulation

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10
Q

What are nodes of Ranvier & what is their function?

A

The gaps formed between the myelin sheath were the axons are left uncovered so the action potential can speed up

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11
Q

Why is the whole of the neuron not insulated with myelin?

A

There wouldn’t be any gaps to speed up the electrical impulse so the electrical impulse would carry the impulse very slowly

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12
Q

What is the function of the axon?

A

To transmit the electrical impulse

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13
Q

What is the function of the axon terminals?

A

Carries neurotransmitters in vesicles

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14
Q

What are the 3 types of neurone?

A

Sensory
Motor
Relay

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15
Q

What is the structure of the sensory neurone?

A

Cell body in the middle
Long dendrites
Has dendrons
Short axons

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16
Q

What is the function of the sensory neurone?

A

Brings impulses from the sensory organs into the CNS

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17
Q

What is the structure of a motor neurone?

A

Cell body at the dendrite end
Short dendrites
No dendrons
Long axon

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18
Q

What is the function of the motor neuron?

A

Carries the electrical impulse from the CNS to the effector organs (muscles/glands)

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19
Q

What is the structure of the relay neurone?

A

cell body in the body
Long dendrites
No dendrons
Short axon

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20
Q

What are the major structures in the brain?

A

Cerebral cortex
White matter
Grey matter
Lobes
Brain stem
Cerebellum

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21
Q

What the structure of the cerebral cortex?

A

Left & Right Hemispheres

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22
Q

What functions does the cerebral cortex control?

A

Consciousness, intelligence, memory & language

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23
Q

What are the Left & Right hemispheres connected by?

A

The corpus callosum

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24
Q

What is white matter?

A

Nerve cells covered in myelin (gives is it’s white colour)

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25
Q

What is grey matter?

A

The folds of the cerebral cortex

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26
Q

What are the 4 different lobes in the brain?

A

Frontal
Parietal
Temporal
Occipital

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27
Q

What functions does the frontal lobe control?

A

Thinking, planning, organising, problem solving, emotions, personality

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28
Q

What functions does the occipital lobe control?

A

Vision

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29
Q

What functions does the temporal lobe control?

A

Memory, understanding & language

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30
Q

What functions does the parietal lobe control?

A

Movement, orientation, memory & recognition

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31
Q

What is the medulla oblongata?

A

The brain stem

32
Q

What functions does the Medulla oblongata control?

A

Involuntary actions (e.g. heartbeat)

33
Q

What functions does the cerebellum control?

A

Controls balance, gross motor skills & coordination or muscular activity

34
Q

What is action potential?

A

The momentary reversal of membrane potential that is the basis for electrical signalling within neurons

35
Q

What are the 3 components that are involved in controlling the resting & action potential of the neuron?

A

The Na+ K+ pump
The Na+ voltage gated channels
The K+ voltage gated channels

36
Q

How are sodium & potassium ions transported across a membrane through a sodium potassium pump?

A

By active transport (requires energy)

37
Q

How are sodium & potassium ions transported across a membrane through a sodium/potassium voltage gated channel?

A

Facilitated diffusion

38
Q

What is the resting potential of a membrane?

A

-70mV

39
Q

How is the resting potential maintained?

A

The sodium potassium pump is open to pump 3Na+ ions outside the cell & 2K+ ions into the membrane via active transport. Both sodium & potassium voltage gated channels are closed to ensure sodium doesn’t reenter the cell making the cell to positive & potassium cannot leave the cell, making the cell too negative, which allows a resting potential of -70mV to be maintained

40
Q

What is value for the action potential?

A

+40mV

41
Q

What are the 3 steps of the action potential?

A

Depolarisation
Repolarisation
Hyperpolarisation

42
Q

What happens at depolarisation?

A

Both the sodium potassium pump & the sodium voltage gated channels are open to allow sodium ions to enter the cell, making it more positive whereas the K+ voltage gated channel closes so the membrane can be at +40mV

43
Q

What happens during depolarisation & repolarisation?

A

The action potential reaches its peak

44
Q

What happens after depolarisation?

A

Repolarisation

45
Q

What happens during repolarisation?

A

Both the sodium potassium pump & the K+ voltage gated channels are open to allow the potassium ions to leave the cell which makes the membrane increasingly negative. The Na+ voltage gated channel closes to ensure this aswell so the membrane reaches -90mV

46
Q

What happens after repolarisation?

A

Hyperpolarisation

47
Q

What is hyperpolarisation also known as?

A

The refractory period

48
Q

What happens during hyperpolarisation?

A

So that the membrane can return to -70mV both the Na+ & K+ voltage gated channels close but the sodium potassium pump remains open so that the membrane can stay negative but the membrane can become a little bit more postive due to the influx of sodium ions

49
Q

What is the threshold potential?

A

Above -55mV where there is enough sodium voltage gated channels to increase the membrane’s positivity so an action potential can fire?

50
Q

What happens if the threshold potential isnt met & why?

A

An action potential doesn’t fire as an action potential is “ all or nothing”

51
Q

Explain the process of the threshold potential

A

The threshold potential needs to be met so that the action potential can occur & fire. This is above -55mV. This is because an action potential is “all or nothing” which means that this threshold potential must be overcome otherwise the action potential wont fire. This occurs because the stimulus is able to release enough cell signalling molecules that are able to open enough Na+ voltage gated channels so that more sodium ions can enter the cell & make the membrane more positive to the point that is is above -55mV and the action potential can fire

52
Q

What direction does an action potential fire?

A

Unidirectional (From dendrite to terminal buttons)

53
Q

What is saltatory conduction?

A

The ‘jumping’ of action potentials between nodes of Ranvier

54
Q

What are sensory receptors?

A

Receptors found in sensory organs that act as transducers & are specific to one type of stimulus e.g. light

55
Q

Why are sensory receptors specific to one type of stimulus?

A

To ensure responses are coordinated properly

56
Q

What are transducers?

A

Things that turn a stimulus into an electrical impulse/generator potential

57
Q

What are the 4 types of sensory receptor?

A

Mechanoreceptors
Chemoreceptors
Thermoreceptors
Photoreceptors

58
Q

What are the function of Mechanoreceptors?

A

Sensitive towards pressure/movement

59
Q

What is an example of a mechanoreceptor?

A

The pacinian corpuscle

60
Q

What is the function of a chemoreceptor?

A

Receptors that are sensitive towards chemicals e.g. taste

61
Q

What is an example of a chemoreceptor?

A

The olfactory receptor

62
Q

What is the function of thermoreceptors?

A

Receptors that are sensitive to changes in temperature

63
Q

Where would Thermoreceptors usually be found in the body?

A

Present on the tongue & the skin’s surface

64
Q

What is the function of photoreceptors?

A

Receptors that are sensitive towards light

65
Q

Where would photoreceptors usually be found in the body?

A

Present in the cone cells in the retina of the eyes

66
Q

What is the pacinian corpuscle?

A

A specific mechanoreceptor sensitive towards pressure & movement

67
Q

Where is the pacinian corpuscle found in the body?

A

In the fingertips/soles of the feet & in the joints

68
Q

What is the structure of the pacinian corpuscle?

A

Stretch-mediated sodium ion channels
Capsule
Connective tissue
Gel
Sensory neurone

69
Q

Describe what happens to the pacinian corpuscle at resting state

A

The stretch-mediated are closed so the sodium ions on the outside cannot enter the cell. This makes the inside of the sensory neurone negative & the outside of the membrane positive so no action potential fires down the sensory neurone

70
Q

Describe what happens when pressure is applied to the pacinian corpuscle?

A

The shape of the pacinian corpuscle changes so the stretch-mediated sodium ion channels open. Due to the high electro-chemical gradient of sodium ions outside they diffuse into the sensory neurone & depolarise the membrane. This initiates a generator potential that is similar to a threshold potential & triggers an action potential down the sensory neurone to the CNS (brain)

71
Q

Why are action potentials described as unidirectional?

A

The dendrites are found at one end of the cell & the axon terminals are found at the opposite end, meaning that the action potential can only travel in one direction

Sodium ions are positive so they travel in the direction of negativity, so it jumps to the next node of ranvier through localised currents in unmyelinated neurons

72
Q

Why are action potentials described as “all or nothing”?

A

The stimulus must be strong enough to open all of the voltage-gated channels to cause the membrane to overpass the threshold potential

73
Q

What are the 2 types of neurotransmitter?

A

Excitatory and inhibitory

74
Q

What is an excitatory neurotransmitter?

A

Neurotransmitters that cause an influx of sodium ions that depolarise the membrane

75
Q

What is an inhibitory neurotransmitter?

A

Neurotransmitters that cause potassium ions to leave the membrane causing repolarisation

A Level Biology (18 decks)

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