Synaptic Transmission Flashcards

1
Q

What is the function of gap junctions?

A

Permit ions to flow from one cell to another

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2
Q

Where are gap junctions present?

A

Myocardial cells, hepatocytes, intestinal smooth muscle ,
retinal cells and neurons

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3
Q

What is EPSP?

A

Transient depolarization in post synaptic membrane
Opening of ion channels permeable to both Na and K

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4
Q

What is a decrement of EPSP a function of?

A

Time and length constant of the membrane

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5
Q

Are potentials all or none in EPSP?

A

Potentials are graded
Summation may be temporal (t) or spatial (I)

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6
Q

What is the t-membrane time constant?

A

Time it takes Vm to move 63% of way towards final value

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7
Q

What makes up the temporal summation?

A

Rising and falling phase of the synaptic potential?

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8
Q

Define the membrane length constant.

A

Distance along a dendrite to the site where the change in Vm has decayed to 37% of its value

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9
Q

What properties increase the length constant?

A

Better insulation of membrane and conducting properties of inner core

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10
Q

What is electrotonic conduction?

A

Passive spread of voltage along neuron

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11
Q

What is EPSP summation comprised of?

A

Spatial and temporal summation

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12
Q

What can the temporal summation do?

A

Drive the membrane potential to the threshold for an action potential
Effect of changing the time constant

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13
Q

What are postsynaptic responses mediated by?

A

NMDA ionotropic glutamate receptor

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14
Q

What is the function of CaMKII?

A

Phosphorylates the AMPA receptor (1)
Trafficks AMPAR (2) and (3)

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15
Q

What is the effect of increasing AMPA receptors?

A

Results in a larger EPSP

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16
Q

What is the IPSP?

A

Hyperpolarizing response to transmitter release
Opening of Cl- channels in post synaptic membrane

17
Q

What does the IPSP cause?

A

Membrane hyperpolarization
Stabilizes membrane potential near ECI
Increases membrane conductance - reduces size of EPSP

18
Q

Define neurotransmitter.

A

Chemical substance secreted by a presynaptic neuron at the synapse, to act on a receptor on the postsynaptic neuron to excite it, inhibit or modify its sensitivity

19
Q

What is the difference between chemical and electrical synapses?

A

Chemical synapses are one directional while electrical synapse transmission is bidirectional

20
Q

What are ionotropic receptors?

A

Neurotransmitter receptors that directly open and gate ion channels

21
Q

What are metabotropic receptors?

A

Neurotransmitter receptors that act through second messenger systems