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BMA1901-Module 3 > Mod 3-Obj11: Synapse > Flashcards

Mod 3-Obj11: Synapse Flashcards

1
Q

Synapses

A

A synapse is a junction that mediates information transfer from one neuron to:

  1. ) Another neuron
  2. ) A muscle = neuromuscular junction
  3. ) A gland = neuroglandular junction
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2
Q

The neuron transmitting the signal

A

Presynaptic neuron

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3
Q

The cell receiving the signal

A

Postsynaptic neuron

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4
Q

Chemical synapses

A

Most abundant type of synapse

  • Presynaptic and postsynaptic membranes are separated by a synaptic cleft
  • Signal transmission involves chemical neurotransmitters
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5
Q

Binding of neurotransmitter opens chemically-gated ion channels…

A

Graded potential produced

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6
Q

If graded potential depolarises the postsynaptic cell to threshold…

A

New action potential generated & signal transmitted

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7
Q

Signal transmission across a chemical synapse: Step 1

A

Action potential arrives at the presynaptic axon terminal

and depolarises the membrane

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8
Q

Signal transmission across a chemical synapse: Step 2

A

Voltage-gated Ca2+ channels open & Ca2+ enters the axon

terminal

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9
Q

Signal transmission across a chemical synapse: Step 3

A

Ca2+ surge triggers synaptic vesicles to release their stored
neurotransmitter (e.g. ACh) into the synaptic clef

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10
Q

Signal transmission across a chemical synapse: Step 4

A

Neurotransmitter diffuses across synaptic cleft and binds to
receptors (chemically-gated ion channels) on the
postsynaptic membrane

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11
Q

Signal transmission across a chemical synapse: Step 5

A

Chemically-gated ion channels open and a graded

potential is produced

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12
Q

Signal transmission across a chemical synapse: Step 6

A

to threshold, voltage-gated Na+ channels open, a new action potential is generated and the signal is transmitted

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13
Q

Termination of signal transmitter…

A

Within a few milliseconds the neurotransmitter

  • Is degraded by enzymes
  • Re-enters axon terminal
  • Diffuses away from synaptic cleft
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14
Q

In response to a stimulus a graded potential is generated…

A

When a stimulus triggers the opening of chemically or mechanically gated channels, present along the plasma membrane of the dendrites

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15
Q

In response to a stimulus an action potential is generated…

A

If the graded potential depolarises the initial segment to threshold -55mV
-An action potential is generated down the length of the axon to the axon terminals

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16
Q

In response to a stimulus an action potential is transmitted…

A

From the axon terminals across a synapse via a chemical neurotransmitter to another neuron or effector muscle or gland

BMA1901-Module 3 (10 decks)

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