nervous system - neurons Flashcards

1
Q

what are neurons?

A

specialised cells to send and receive nerve impulses

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2
Q

what are neuroglia?

A

cells that have a support function
provide insulation and nutrients
may send and receive impulses

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3
Q

how are all the organs in the human body formed?

A

four types of tissue combine

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4
Q

what does nervous tissue do?

A

allow you to sense and respond to things

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5
Q

what do nervous tissue cells do?

A

they are specialised for receiving and sending information

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6
Q

where is the central nervous system?

A

made up of the brain and spinal cord

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7
Q

where is the peripheral nervous system

A

cranial nerves, spinal nerves, ganglia, peripheral nerves, and neuromuscular junctions

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8
Q

what is the function of the cns?

A

awareness, movement, speech, receiving, processing, responding to sensory information

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9
Q

what is the function of the pns?

A

sending information from different areas of the body back to the brain, and carrying out commands from the brain to various parts of the body.

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10
Q

how is the peripheral nervous system further subdivided?

A

into an afferent sensory division and efferent motor division

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11
Q

what are the peripheral organs

A

nerves and ganglia

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12
Q

how does the sensory division of the pns transmit impulses?

A

from the peripheral organs to the cns

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13
Q

how does the motor division of the pns transmit impulses?

A

from the cns to the peripheral organs

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14
Q

how is the motor division further subdivided

A

into a somatic motor division and an autonomic motor division

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15
Q

what does the somatic motor division do?

A

serves skeletal muscle

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16
Q

what does the autonomic motor division do?

A

serves smooth muscle, cardiac muscle and glands

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17
Q

what does the nervous system do?

A

contains sensory receptors which detect changes in the internal and external environment of the body

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18
Q

how does the nervous system send information?

A

via impulses

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19
Q

what are impulses?

A

a network of cells that use electrical signals

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20
Q

what happens when impulses are used?

A

responses are initiated to changes in the body, allowing the nervous system to maintain homeostasis

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21
Q

what does motor function do?

A

carries out effect

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22
Q

what does the integrative function?

A

decides response

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23
Q

what does the sensory function do?

A

detects stimulus / informs cns

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24
Q

what are the effectors of the somatic nervous system?

A

skeletal muscles

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25
Q

what are the effectors of the autonomic nervous system?

A

cardiac muscles, smooth muscle, glands

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26
Q

types of neuroglia

A

astrocytes
ependymal cells
microglia
oligodendrocytes

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27
Q

what is the function of astrocytes

A

found between neurouns and blood vessels (blood brain barrier)
regulate ion concentration in nervous tissue
multifunctional

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28
Q

what is the function of ependymal cells

A

cover the choroid plexus
line spaces in the brain (ventricles)
produce csf

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29
Q

what is the function of microglia

A

function as phagocytes
supportive function

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30
Q

what is the function of oligodendrocytes

A

form myelin in central nervous system

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31
Q

what is csf

A

cerebrospinal fluid: flows in and around the hollow spaces of the brain and spinal cord, and between two of the meninges

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32
Q

what is the node of ranvier?

A

exposed area of axon between myelin
gaps between neighbourign segments of the myselin sheath

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33
Q

what is the myelin sheath

A

a coating formed by schwann cells wrapped around the axon

34
Q

what is an axon?

A

thin extension that carries impulse

35
Q

what cells are axons of the peripheral nervous system associated with

A

neuroglia cells - schwann cells

36
Q

what does the myelin sheath consist of

A

multiple layers of the cell membrane of neuroglia cells

37
Q

what happens when schwann cells wrap around the axon

A

cytoplasm becomes the outermost wrapping of the cell

38
Q

what is the neurilemma

A

the outermost wrapping of the axon containing organelled and nucleus

39
Q

what are myelinated axons

A

axons with myelin sheaths

40
Q

what are unmyelinated axons

A

axons without myelin sheaths

41
Q

what is the cell body of a neuron

A

region that contains the nucleus

42
Q

what is the dendrite of the neuron

A

branched receptive processes

43
Q

what is the synaptic knob

A

enlarged structures that store and release neurotransmitters

44
Q

what is myelin

A

multilayered lipid covering of axon

45
Q

what type of nervous system tissue is formed by bundles of myelinated axons?

A

white matter

46
Q

what is found within gray matter in the nervous system tissue?

A

unmyelinated axons, dendrites, neuron cell bodies, and synapses

47
Q

what happens when an action potential arrives at the synaptic terminal

A

voltage gated calcium channels are opened

48
Q

what neurotransmitter is released from the synaptic vesicles?

A

acetylcholine

49
Q

When do ligand-gated sodium channels open?

A

When their ligand (acetylcholine) binds

50
Q

what happens when sodium enters the sodium channels?

A

the membrane potential becomes more positive.

51
Q

when will an action potential be produced?

A

if the membrane potential reaches threshold

52
Q

What structure releases neurotransmitter molecules?

A

synaptic vesicles

53
Q

how do nerve impulses occur?

A

ions moving through voltage gated ion channels in the plasma membrane

54
Q

The interior of the cell membrane is more__________ than the outside of the cell membrane.

A

negative

55
Q

What direction does the sodium-potassium pump move ions?

A

Sodium out of the cell and potassium into the cell

56
Q

Following stimulation, what are the first channels to open?

A

sodium channels

57
Q

what happens when sodium enters the cell membrane at the location of the sodium channel?

A

depolarisation

58
Q

When potassium channels open, which way do potassium ions flow?

A

out of the cell

59
Q

during an action potential what happens when potassium channels are opened?

A

repolarisation of the cell membrane

60
Q

Following an action potential, activity of the __________ reestablishes the sodium and potassium ion distribution across the cell membrane.

A

sodium potassium pump

61
Q

what does an action potential involve?

A

depolarisation
repolarisation

62
Q

what is the steps of synaptic transmission?

A
  • nerve impulse at axon terminal
  • calcium ions enter
  • exocytosis of neurotransmitter
  • diffusion through synaptic cleft
  • binding to receptor on post synaptic membrane
63
Q

what happens during hyperpolarisation?

A

potassium channels are open
membrane potential actually dips lower than -70mV because the potassium channels do not close quickly enough.

64
Q

how can the cell membrane of a resting neuron be described?

A

polarised

65
Q

what is depolarisation?

A

the membrane potential becomes less negative than the resting membrane potential

66
Q

when will the action potential only occur?

A

the membrane potential at the trigger zone reaches threshold level

67
Q

what happens when threshold is reached?

A

voltage-gated sodium channels of the initial segment open briefly, allowing sodium to diffuse into the cell.

68
Q

what happens when sodium ions enter the cell?

A

the cell membrane undergoes depolarization, with the membrane potential increasing to a peak of approximately +30mV.

69
Q

what happens when the peak of the action potential is reached?

A

sodium channels close, and the voltage-gated potassium channels open, allowing these ions to diffuse out of the cell.

70
Q

what happens when potassium ions leave the cell?

A

the membrane potential at that part of the membrane is reestablishing resting membrane potential. repolarization occurs

71
Q

features of myelinated axon

A

faster impulse conduction
saltatory conduction
only nodes depolarise

72
Q

features of unmyelinated axon

A

slower impulse conduction
entire surface depolarises

73
Q

what is an excitatory neurotransmitter?

A

A neurotransmitter that causes the opening of sodium channels
brings the postsynaptic membrane closer to the threshold

74
Q

what is an inhibitory neurotransmitter?

A

A neurotransmitter that causes the opening of potassium channels
causes membrane potential to move away from the threshold

75
Q

What are examples of a neuropeptide?

A

Enkephalins and substance P

76
Q

what are neuropeptides?

A

small proteinaceous substances produced and released by neurons through the regulated secretory route and acting on neural substrates.

77
Q

how do neurons communicate chemically with eachother?

A

using neurotransmitters at a synapse

78
Q

the release of neurotransmitters by the ________ is triggered by nerve impulses

A

presynaptic neuron

79
Q

what happens when the neurotransmitter binds to the post synaptic neuron?

A

causes electrical changes in the membrane

80
Q
A