How Nerves Work 5

Question 1

<p>What is the neuromuscular junction?</p>

Answer 1

<p>Junction between the skeletal muscle and motor neuron</p>

Question 2

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

Answer 2

<p>Always</p>

Question 3

<p>Why are there fold at the neuromuscular junction?</p>

Answer 3

<p>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</p>

Question 4

<p>Why is acetylcholine removed afterwards?</p>

Answer 4

<p>To stop any spasms occuring as many action potentials are fired</p>

Question 5

<p>What is the process of an action potential being fired at the neuromuscular junction?</p>

Answer 5

<ol> <li>Action potential travls down motor neuron</li> <li>Opens voltage gated Ca²⁺channels in presynaptic terminal</li> <li>Triggers fussion of vesicles (Ca²⁺dependent exocytosis)</li> <li>Acetylcholine is released</li> <li>Diffuses across the synaptic cleft and binds to acetylcholine receptors</li> <li>Opens ligand gated Na⁺/K⁺channels</li> <li>Evokes graded potential (end plate potential)</li> <li>Always depolarises adjacent membranes to threshold</li> <li>Opens voltage gated Na⁺channels evoking a new action potential</li> <li>Acetylcholine removed by acetylcholinesterase</li></ol>

Question 6

<p>What is the process of synaptic transmission in the CNS?</p>

Answer 6

<ol> <li>Action potential releases terminal</li> <li>Voltage gated Ca²⁺channels open</li> <li>Ca²⁺enters axon terminal</li> <li>Neurotransmitter released and diffusion</li> <li>Neurotransmitter binds to post-synaptic receptors</li> <li>Neurotransmitter removed from synaptic cleft</li></ol>

Question 7

<p>What are some examples of neurotransmitters used in the CNS?</p>

Answer 7

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

Question 8

<p>How does the neuromuscular junction and CNS differ in the neurostransmitters that they use?</p>

Answer 8

<p>CNS uses a range of neurotransmitters whereas theneuromuscular junction only uses acetylcholine</p>

Question 9

<p>How many receptors does each neurotransmitter have (one or several)?</p>

Answer 9

<p>Several</p>

Question 10

<p>What receptor does acetylcholine act on at the neuromuscular junction?</p>

Answer 10

<p>Nicotinic</p>

Question 11

<p>Do the CNS and neuromuscular junction both use a range of postsynaptic potentials?</p>

Answer 11

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

Question 12

<p>What is the advantage of many small kinds of postsynaptic potentials?</p>

Answer 12

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

Question 13

<p>What are the different anatomical arrangements of synapses in the CNS?</p>

Answer 13

<p>Axo somatic (onto soma)</p>

<p>Axo dendritic (onto dendrite)</p>

<p>Axo axonal (onto terminal of other fibre)</p>

Question 14

<p>Which form of synaptic anatomical arrangement in the CNS usually produces the largest response?</p>

Answer 14

<p>Axo somatic (onto the soma)</p>

Question 15

<p>What are the two forms of synaptic connectivity?</p>

Answer 15

<p>Convergence</p>

<p>Divergence</p>

Question 16

<p>Where is synaptic connectivity used?</p>

Answer 16

<p>In the CNS</p>

Question 17

<p>What can synaptic connectivity be used for?</p>

Answer 17

<p>Feedback inhibition to stop a neuron from firing more than once</p>

Question 18

<p>What pathways of neurons can be found in the CNS?</p>

Answer 18

<p>Monosynaptic</p>

<p>Polysynaptic</p>

Question 19

<p>What do monosynaptic pathways look like?</p>

Answer 19

<p>Sensory - inter - motor</p>

Question 20

<p>What do polysynaptic pathways look like?</p>

Answer 20

<p>Lots of synapses between the sensory and motor</p>

Question 21

<p>Why is the CNS more complex than the neuromuscular junction?</p>

Answer 21

<p>Range of neurotransmitters</p>

<p>Range of postsynaptic potentials</p>

<p>Small potentials (use synaptic integration)</p>

<p>Variations of anatomical arrangements</p>

<p>Variations on connectivity of neuron</p>

Question 22

<p>How can the actions of drugs be explained by the mechanism of the NMJ?</p>

Answer 22

<p>They inhibity different aspects of it</p>