How Nerves Work 5 Flashcards

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1
Q

What is the neuromuscular junction?

A

Junction between the skeletal muscle and motor neuron

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2
Q

Does the cell at the neuromuscular junction always or sometimes reach threshold when acetylcholine is released?

A

Always

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3
Q

Why are there fold at the neuromuscular junction?

A

Allows more voltage gated Na+ channels to be closer to the ligand gated acetylcholine receptor so the graded potential doesn’t have far to go

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4
Q

Why is acetylcholine removed afterwards?

A

To stop any spasms occuring as many action potentials are fired

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5
Q

What is the process of an action potential being fired at the neuromuscular junction?

A
  1. Action potential travls down motor neuron
  2. Opens voltage gated Ca2+ channels in presynaptic terminal
  3. Triggers fussion of vesicles (Ca2+ dependent exocytosis)
  4. Acetylcholine is released
  5. Diffuses across the synaptic cleft and binds to acetylcholine receptors
  6. Opens ligand gated Na+/K+ channels
  7. Evokes graded potential (end plate potential)
  8. Always depolarises adjacent membranes to threshold
  9. Opens voltage gated Na+ channels evoking a new action potential
  10. Acetylcholine removed by acetylcholinesterase
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6
Q

What is the process of synaptic transmission in the CNS?

A
  1. Action potential releases terminal
  2. Voltage gated Ca2+ channels open
  3. Ca2+ enters axon terminal
  4. Neurotransmitter released and diffusion
  5. Neurotransmitter binds to post-synaptic receptors
  6. Neurotransmitter removed from synaptic cleft
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7
Q

What are some examples of neurotransmitters used in the CNS?

A

Acetylcholine
Noradrenaline
Dopamine
Serotonin
Histamine
Glutamine
GABA
Glycine
Peptide
ATP
Adenosine
Nitric oxide (not in vesicle as lipphillic, produced on deman)

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8
Q

How does the neuromuscular junction and CNS differ in the neurostransmitters that they use?

A

CNS uses a range of neurotransmitters whereas theneuromuscular junction only uses acetylcholine

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9
Q

How many receptors does each neurotransmitter have (one or several)?

A

Several

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10
Q

What receptor does acetylcholine act on at the neuromuscular junction?

A

Nicotinic

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11
Q

Do the CNS and neuromuscular junction both use a range of postsynaptic potentials?

A

No, the CNS uses a wide range (fast IPSP, slow IPSP, fast EPSP and slow EPSP) whereas the neuromuscular junction always depolarises

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12
Q

What is the advantage of many small kinds of postsynaptic potentials?

A

Enables synaptic integration to use lots of information to determine if an action potential should be fired

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13
Q

What are the different anatomical arrangements of synapses in the CNS?

A

Axo somatic (onto soma)

Axo dendritic (onto dendrite)

Axo axonal (onto terminal of other fibre)

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14
Q

Which form of synaptic anatomical arrangement in the CNS usually produces the largest response?

A

Axo somatic (onto the soma)

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15
Q

What are the two forms of synaptic connectivity?

A

Convergence

Divergence

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16
Q

Where is synaptic connectivity used?

A

In the CNS

17
Q

What can synaptic connectivity be used for?

A

Feedback inhibition to stop a neuron from firing more than once

18
Q

What pathways of neurons can be found in the CNS?

A

Monosynaptic

Polysynaptic

19
Q

What do monosynaptic pathways look like?

A

Sensory - inter - motor

20
Q

What do polysynaptic pathways look like?

A

Lots of synapses between the sensory and motor

21
Q

Why is the CNS more complex than the neuromuscular junction?

A

Range of neurotransmitters

Range of postsynaptic potentials

Small potentials (use synaptic integration)

Variations of anatomical arrangements

Variations on connectivity of neuron

22
Q

How can the actions of drugs be explained by the mechanism of the NMJ?

A

They inhibity different aspects of it