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PSYC5002 > L3: Action Potentials > Flashcards

L3: Action Potentials Flashcards

1
Q

True of False. At rest potassium is pretty close to it’s equilibrium potential

A

True - potassium equil. potential is -90, resting cell is -70mV

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2
Q

How does action potential travel down axon?

A

sodium continues to enter the cell all the way down axon

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3
Q

True of false. the cell membrane generally prevents ions moving around

A

True. This is thanks to the phospholid bilayer.

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4
Q

Define synapse

A
  • Communication between two neurons
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5
Q

what is overshoot

A

when cell membrane’s voltage goes above 0mV

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6
Q

Two types of synapses

A

Electrical
Chemical

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7
Q

Electrical synapses are also known as

A

Gap Junctions

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8
Q

Can another action potential be fired in relative refractory period?

A

Yes. But requires much more excitation to reach threshold and stimulate another action potential

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9
Q

what is depolarisation

A

cells membrane voltage is rising

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10
Q

If a stimulus comes in that does not reach the threshold, it is called a _____

A

subthreshold EPSP

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11
Q

Where does sodium enter axon

A

through nodes of ranvier. Does not enter on parts of axon coated with myelin sheath

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12
Q

Is sodium more concentrated outside the cell or inside

A

outside

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13
Q

axoaxonic synaptic communication involves communication from an axon >>> _____

A

axon of another cell (generally to inhibit synaptic communciation)

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14
Q

Increases in voltage are _____ _______ ____ (____)

A

Excitatory PostSynaptic Potentials (EPSPs)

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15
Q

what is the main purpose of the phospholid bilayer of the cell membrane

A

To maintain negative charge within the cell

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16
Q

What is an action potential? One sentence

A

A nerve impulse. A rapid, electrical signal that travels down a single cell

“neuron firing”

17
Q

When graded potentials are being summed can IPSPs and EPSPs cancel each other out?

A

Yes

18
Q

Can another action potential be fired in absolute refractory period?

A

no

19
Q

axosomatic synaptic communication involves communication from an axon >>> ______

A

cell body

20
Q

What are the sevem steps of synaptic communication

A
  1. Nerve impulse at axon terminal of presynaptic neuron
  2. Voltage gated calcium channels open ® calcium enters cell
  3. ­ calcium levels activate synaptic vesicles
  4. Activation of vesicles ® release of neurotransmitters into synaptic cleft
  5. The neurotransmitter in the synaptic cleft free to bind to receptors on postsynaptic neuron
  6. Neurotransmitter binds to a receptor > a ligand-gated ion channel opens. positively charged = excitation. Or chloride channel opens = inhibition.
  7. Excitation or inhibition (change of voltage) of post-synaptic cell = postsynaptic potential (or graded potential)
21
Q

Decreases in voltage are ____ ________ _______ (____)

A

inhibitary PostSynaptic Potentials (IPSPs)

22
Q

True or false. Positive ions like sodium and potassium are drawn to positively charged space.

A

False. drawn to negatively charge space

23
Q

True of False. Sodium generally wants to get into the cell because its equilibrium potential is +55mV

A

True

24
Q

What is the equilibrium potential of Sodium

A

+55mV

25
Q

What is the resting membrane potential

A

-70mV

26
Q

Outline what occurs when threshold is met in the axon hillock

A
  1. threshold met
  2. voltage gated sodium channels open > sodium floods in
  3. sodium drives up membrane voltage of cell (depolarisation)
  4. voltage gates close
  5. potassium uncomfortable >> moves out of the cell through potassium channels
  6. potassium leaving > reduced voltage (repolarisation)
  7. potassium continues to leave > hyperpolarisation
27
Q

True of false. An action potential will only fire once the threshold is reached at the axon hillock

A

True

28
Q

How do cells communicate through electrical synapses

A

Ions move directly across the channels so neurons have to be VERY close together

29
Q

In basic terms, what does a chemical synapse involve?

A

Involves the release of a neurotransmitter which binds to a receptor on a post synaptic neuron

30
Q

What are graded potentials. Where do they travel to?

A

Neurons get info from other cells at synapses, changing the electrical charge of the cell membrane.

Graded potentials move across cell membrane to axon hillock

31
Q

axodentritic synaptic communication involves communication from an axon >>> _____

A

dendrite

32
Q

What is the equilibrium potential of Potassium

A

-90mV

33
Q

What is the main reason ions don’t evenly split themselves inside and outside the cell when channels are open

A

electrical potential difference. When the cell membrane becomes permeable to any ion movement, each ion it going to drive the membrane potential of the cell toward it’s equilibrium potential

34
Q

is potassium more concentrated outside the cell or inside

A

inside

35
Q

Are electrical or chemical synapses faster

A

electrical

36
Q

Are electrical or chemical synapses more common

A

chemical

PSYC5002 (9 decks)

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