5.3-nerves (why is this hard) Flashcards

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1
Q

where is the cell body of a motor neurone found?

A

spinal cord or brain

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2
Q

what is a Dendron?

A

long projection that carries impulse towards a cell body

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3
Q

where are the cell bodies of sensory neurones found?

A

dorsal root ganglia, just outside the spinal cord

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4
Q

what produces myelin?

A

Schwann cells

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5
Q

what is salutatory conduction?

A

when the nerve impulses jump from node to node

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6
Q

what is the function of myelin?

A

speeds up nerve impulses

insulates neurone

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7
Q

why are not all nerves myelinated?

A

not necessary: short neurones, thick axons

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8
Q

where’s the myelin in non myelinated neurones and why?

A

neurones not individually wrapped but still associated with myelin, because it helps keep nerve alive and is involved in regeneration.

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9
Q

what is a fibroblast?

A

specialised tissue found in pacinian corpuscles

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10
Q

what is the axon hillock?

A

where the action potential will propagate from

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11
Q

what is an action potential?

A

a brief reversal of the potential across the membrane of the neurone.

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12
Q

what type of neurone has dendrites?

A

motor

relay

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13
Q

what type of neurone has a Dendron?

A

sensory

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14
Q

what are the channels like in a neurone at resting potential?

A

Na+/K+ pump going
Na+ channels closed
some K+ channels open

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15
Q

what are the channels like in a neurone when the stimulus is detected?

A

Na+ channels open
Na+/K+ pump still going
K+ channels closed

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16
Q

what are the channels like in a neurone during depolarisation?

A

Na+ channels open
voltage gated Na+ channels open
Na+/K+ pump still going

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17
Q

why is transmission of action potentials along the axon slower in the absence of saltatory conduction?

A

no nodes of ranvier
shorter local currents
whole axon needs to be depolarised

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18
Q

what is a pacinian corpuscle?

A

pressure sensor found in the skin

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19
Q

what is a transducer?

A

cell that converts one form of energy to another

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20
Q

which sensory receptors detect a change in light intensity?

A

rods and cones in retina

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21
Q

which sensory receptors detect a change in pressure on skin?

A

pacinian corpuscles

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22
Q

which sensory receptors detect movement?

A

hair cells in inner ear

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23
Q

which sensory receptors detect change in muscle length?

A

muscle spindles in skeletal muscle

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24
Q

which sensory receptors detect chemicals in the air?

A

olfactory cells in epithelium lining fo nose

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25
Q

what’s a pacinian corpuscle made of ?

A

series of concentric rings of connective tissue wrapped round the end of a nerve cell

26
Q

what happens to the pacinian corpuscle when pressure on the skin changes?

A

rings of connective tissue get deformed-pushes against nerve ending-sodium channels open-generator potential

27
Q

in the pacinian corpuscle what produces the connective tissue?

A

fibroblast

28
Q

what is a generator potential also called?

A

receptor potential

29
Q

what does it mean when a neurone is polarised?

A

negatively charged inside compared to outside

30
Q

what is a generator potential?

A

change in potential across a receptor membrane

31
Q

what are non myelinated neurones often used in?

A

coordinating body functions eg breathing and action of digestive system

32
Q

what is an action potential?

A

brief reversal of the potential across the membrane of a neurone

33
Q

whats the voltage of a neurone during an action potential?

A

+40mV

34
Q

whats the resting potential of a neurone?

A

-60-70 mV

35
Q

why are action potentials referred to as an all or nothing response?

A

all action potential are the same magnitude-the strength of stimulus is transmitted as more frequent action potentials, not bigger ones.

36
Q

what are the brief stages of an action potential?

A

resting
Na+ channels open-Na+ goes into cell
membrane depolarises-reaches threshold of -50mV
voltage gated Na+ open-loads of Na+ go in-reaches +40mV
Na+ close, K+ open-K+ diffuse out bringing pd back to negative-repolarisation
hyperpolarisation then resting

37
Q

what is the refractory period?

A

a short time where after the action potential it’s impossible to get another one-allows cell to recover, ensures APs only transmitted 1 direction

38
Q

why does the action potential continue to move in the same direction during transmission?

A

conc of Na+behind AP still high

39
Q

what is a cholinergic synapse?

A

synapse that uses acetylcholine as its neurotransmitter

40
Q

what is a neurotransmitter?

A

chemical used as signalling molecule between 2 neurones in a synapse

41
Q

what is a synapse?

A

a junction between 2 or more neurones

42
Q

what is between the 2 neurones in a synapse?

A

synaptic cleft

43
Q

the pre synaptic neurone ends in a…

A

swelling called the pre-synaptic bulb or knob

44
Q

what are the specialised features of the pre synaptic bulb?

A

many mitochondria
lots of SER
lots of vesicles
Ca2+ channels on surface membrane

45
Q

why does the pre synaptic bulb have loads of SER?

A

it packages the neurotransmitter into vesicles

46
Q

what does the post synaptic membrane contain?

A

specialised Na+ channels that respond to neurotransmitter

47
Q

what happens to the Na+ channels on the post synaptic membrane when neurotransmitter is present?

A

neurotransmitter binds to 2 receptor sites on Na+ channels-they open

48
Q

what reaction does acetylcholinesterase catalyse?

A

acetylcholine–> ethanoic (acetic) acid + choline

49
Q

what happens to the ethanoic (acetic) acid + choline after they’ve gotten made?

A

recycled-enter synaptic bulb by diffusion+made back into acetylcholine using ATP fro mitochondria.

50
Q

when does summation occur?

A

when the effects of several EPSPs are added together

51
Q

what’s the difference between temporal and spatial summation?

A

temporal: all from same pre synaptic neurone
spatial: from different ones

52
Q

what do IPSPs do?

A

reduce effect of summation+prevent action potential in post synaptic neurone

53
Q

what is an EPSP?

A

excitatory post synaptic potential-small post synaptic potential that makes neurone more likely to fire action potential

54
Q

what is an IPSP?

A

inhibitory post synaptic potential-synaptic potential that makes post-synaptic neurone less likely to generate an action potential, neurotransmitters may bind to post synaptic membrane + close ion channels.

55
Q

when could spatial summation be useful?

A

when several different stimuli are warning of danger

56
Q

when is 1 pre synaptic leading to many post synaptic neurones useful?

A

reflex arc-one yeets and does the reflex the other informs the brain

57
Q

if a low level stimulus creates an action potential in the pre synaptic neurone why is it unlikely to pass through the synapse to the next neurone?

A

several vesicles of neurotransmitter must be released to create action potential in post synaptic neurone

58
Q

after repeated stimulation what might happen to a synapse?

A

may run out of vesicles containing neurotransmitter-synapse said to be fatigued

59
Q

what happens when we become habituated to something?

A

nervous system no longer responds to the stimulus

60
Q

what is a direct effect of the neurotransmitter binding to the receptor on the post synaptic neurone?

A

Na+ travels through postsynaptic membrane.