Topic 3 - NERVOUS SYSTEM I (Neuronal Physiology - Post Synaptic Potentials) Flashcards

1
Q

PSP’s may be:

A
  1. excitatory PSPs (EPSPs)
  2. inhibitory PSPs (IPSPs)
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2
Q

Excitatory PSPs

A
  • = Graded Potential ⇒ depolarization
  • due to opening of Na+ (or Ca++) channels, or closing of K+ channels
  • neurotransmitter is often acetylcholine or glutamate
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3
Q

Inhibitory PSPs

A
  • due to opening of K+ pr Cl- channels
    • inhibits neuron from reaching threshold
  • neurotransmitter is often glycine or GABA
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4
Q

PSPs occur where?

A

PSPs occur on cell body or dendrites

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5
Q

PSPs occur on cell body or dendrites

what are the steps?

A
  1. many neurons can synapse onto one
  2. if many EPSP
  3. summation
  4. large area of membrane depolarized
  5. spreads to axon hillock
  6. if (sum of) EPSP is strong enough
  7. get ACTION POTENTIAL
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6
Q

some may be IPSP…what determines if AP will occur on axon hillock?

A
  1. the sum of all EPSPs and IPSPs determines if AP will occur on axon hillock
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7
Q

Synaptic Transmission at the Neuromuscular Junction:

where is the junction located?

A

junction between axon terminal and an individual muscle fibre

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8
Q

Synaptic Transmission at the Neuromuscular Junction:

steps = similar to those for neuronal junction with the following modifications

Step 1

    1. Na+ chemical gates on muscle motor end plate (=sarcolemma of muscle fibre) open
      * causes graded potential (=end plate potential) on sarcolemma
  1. EPP triggers action potential on sarcolemma
    • lots of acetylcholine (ACh) released in step 1 therefore always gets an AP from an EPP
A

Neurotransmitter is released = always acetylcholine (ACh)

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9
Q

Synaptic Transmission at the Neuromuscular Junction:

steps = similar to those for neuronal junction with the following modifications

Step 2

  1. Neurotransmitter is released = always acetylcholine (ACh)
  2. Na+ chemical gates on muscle motor end plate (=sarcolemma of muscle fibre) open
    • causes graded potential (=end plate potential) on sarcolemma
  3. EPP triggers action potential on sarcolemma
    • lots of acetylcholine (ACh) released in step 1 therefore always gets an AP from an EPP
A
  • Na+ chemical gates on muscle motor end plate (=sarcolemma of muscle fibre) open
    • causes graded potential (=end plate potential) on sarcolemma
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10
Q

Synaptic Transmission at the Neuromuscular Junction:

steps = similar to those for neuronal junction with the following modifications

Step 3

  1. Neurotransmitter is released = always acetylcholine (ACh)
  2. Na+ chemical gates on muscle motor end plate (=sarcolemma of muscle fibre) open
    • causes graded potential (=end plate potential) on sarcolemma
      3.
A

End plate potential triggers action potential on sarcolemma

  • lots of acetylcholine (ACh) released in step 1 therefore always gets an AP from an EPP
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11
Q

Synaptic Transmissions at Neuronal Junction

NS depends on?

A

chains of neurons connected by junctions called synapses

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12
Q

Synaptic Transmissions at Neuronal Junction

what depends on chains of neurons connected by junctions called synapses?

A

NS

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13
Q

Synaptic Transmissions at Neuronal Junction

NS depends on chains of neurons connected by junctions called?

A

synapses

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14
Q

Synaptic Transmissions at Neuronal Junction

Presynpaptic neuron to Post synaptic Neuron transmission:

5 steps

  1. AP arrives where?
  2. Ca++ voltage gates open (Due to AP) and Ca++ enters (higher [Ca++] outside)
  3. Rise in Ca++ triggers exocytosis of vesicles containing neurotransmitter
  4. neurotransmitter corsses cleft, binds to specific receptors on postsynaptic membrane
  5. gated ion channels open - allowing movement of ions into (or out of postsynaptic membrane)
A

AP arrives at axon terminal (synaptic end bulb)

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15
Q

Synaptic Transmissions at Neuronal Junction

Presynpaptic neuron to Post synaptic Neuron transmission:

5 steps

  1. AP arrives at axon terminal (synaptic end bulb)
  2. what voltage gates open and enters?
  3. Rise in Ca++ triggers exocytosis of vesicles containing neurotransmitter
  4. neurotransmitter corsses cleft, binds to specific receptors on postsynaptic membrane
  5. gated ion channels open - allowing movement of ions into (or out of postsynaptic membrane)
A

Ca++ voltage gates open (Due to AP) and Ca++ enters (higher [Ca++] outside)

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16
Q

Synaptic Transmissions at Neuronal Junction

Presynpaptic neuron to Post synaptic Neuron transmission:

5 steps

  1. AP arrives at axon terminal (synaptic end bulb)
  2. Ca++ voltage gates open (Due to AP) and Ca++ enters (higher [Ca++] outside)
  3. rise in what? containing what?
  4. neurotransmitter corsses cleft, binds to specific receptors on postsynaptic membrane
  5. gated ion channels open - allowing movement of ions into (or out of postsynaptic membrane)
A

Rise in Ca++ triggers exocytosis of vesicles containing neurotransmitter

17
Q

Synaptic Transmissions at Neuronal Junction

Presynpaptic neuron to Post synaptic Neuron transmission:

5 steps

  1. AP arrives at axon terminal (synaptic end bulb)
  2. Ca++ voltage gates open (Due to AP) and Ca++ enters (higher [Ca++] outside)
  3. Rise in Ca++ triggers exocytosis of vesicles containing neurotransmitter
  4. what crosses where? and binds to what on where?
  5. gated ion channels open - allowing movement of ions into (or out of postsynaptic membrane)
A

neurotransmitter crosses cleft, binds to specific receptors on postsynaptic membrane

  • receptors are (or act on) chemically gated ion channels - open in response to neurotransmitter
18
Q

Synaptic Transmissions at Neuronal Junction

Presynpaptic neuron to Post synaptic Neuron transmission:

5 steps

  1. AP arrives at axon terminal (synaptic end bulb)
  2. Ca++ voltage gates open (Due to AP) and Ca++ enters (higher [Ca++] outside)
  3. Rise in Ca++ triggers exocytosis of vesicles containing neurotransmitter
  4. neurotransmitter crosses cleft, binds to specific receptors on postsynaptic membrane
  5. what opens here and what does this allow?
A

gated ion channels open - allowing movement of ions into (or out of postsynaptic membrane)

  • creates a graded potential called a postsynaptic potential