Lecture 5 - action potential Flashcards

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1
Q

What is action potential?

A
  • electrical impulses send signals
  • temporary shift in membrane (elec.) potential
  • causes the release of NTs
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2
Q

What causes action potential?

A
  • it starts when a NT binds to the receptor
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3
Q

What is the voltage change for action potential?

A

-70mV to +50mV

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4
Q

At what charge do Na+ channels open?

A

-50mV (negative 50)

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5
Q

What happens when Na+ channels open?

A

The cell gets really positive really fast

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6
Q

At what voltage do K+ channels open up?

A

+50mV

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7
Q

What is the axon hillock?

A

Where all the electrical energy in the cell ends up to determine if there will be an action potential propagating through (moving along) the axon

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8
Q

What happens when the action potential reaches the terminal?

A
  • It causes the release of NTs from the terminals
  • The NT does not enter the new cell, it just binds to the receptor
  • Opens ion channel for the new neuron
  • in the membrane of the terminal, there are Ca++ voltage-gated channels
  • Action potential activates Ca++ channels
  • when the Ca++ channels open, the terminal membrane and vesicle membrane blend together/fuse
  • NT binds to receptor
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9
Q

The pufferfish contains tetradotoxin, this toxin blocks Na+ voltage-gated channels what will happen to the action potential? What will happen to the transmission in the neuron?

A

If the Na+ voltage-gated channels can’t open, action potential can’t occur. There will be no transmission in the neuron

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10
Q

Draw an action potential indicating what causes the changes in charge (eg Na+ goes in…)

A
  • at -50mV, Na+ goes in, neuron shoots up (positive)
  • at +50mV, K+ channels open, K+ goes out, cell becomes super negative
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11
Q

Draw an action potential indicating what causes the changes in charge (eg Na+ goes in…)

A
  • at -50mV, Na+ goes in, neuron shoots up (positive)
    –> Depolarizing phase
  • at +50mV, K+ channels open, K+ goes out, cell becomes super negative
    –> Repolarizing phase
  • cell temporarily gets lower than -70mV
    –> undershoot
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12
Q

Where in the neuron is action potential generated? Why this location?

A
  • Action potential only happens at the nodes of ranvier
  • It happens at the nodes because…
    1. that’s the only place on the axon where there
      isn’t myelin
    2. that’s the only place where there are voltage-
      gated channels
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13
Q

The action potential starts in the axon hillock. Why does it start in the AH and not dendrites?

A
  • Dendrites DO NOT have voltage-gated channels
  • AH DOES have voltage-gated channels
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14
Q

What causes the release of NTs? What happens to the NTs after they’re released? What happens after that?

A
  • at the membrane of the terminal, there are Ca++ channels
  • they open up, which causes the membrane to blend/fuse
  • the NT crosses the synapse and binds to the receptor of the post-synaptic neuron
  • the NT causes ion channels to open on the post-synaptic neuron, which changes its charge
    –> can make it generate its own action potential
    –> can make the neuron inhibited
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15
Q

List 3 characteristics of a substance to be classified as a NT

A
  1. it must be created by and stored in a neuron
  2. it must be the only thing causing the reaction
    –> If you experimentally put only the neurotransmitter on the receptor, the postsynaptic cell would respond the same way
  3. it must be able to return to the original neuron
  4. it must be released when the neuron is excited
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16
Q

List the 5 types of NTs

A
  1. Amino acids.
  2. Amines.
  3. Acetylcholine (Ach.)
  4. Peptides.
  5. Non-traditional.
17
Q

What is DA? What type of NT?

A

Dopamine
Amines –> monoamine

18
Q

What is NE? What type of NT?

A

norepinephrine
Amines –> monoamine

19
Q

What is 5-HT? What type of NT?

A

Seratonin
Amines

20
Q

What is GABA? What type of NT?

A

Gamma-AMINO butyric Acid
Amino acid

21
Q

What type of NT is ACh?

A

Acetylcholine

22
Q

What does ACh affect? What problem is associated with it?

A

Memory and muscular contractions
Alzheimers

23
Q

What problem is associated with monoamines?

A

Key cause of mental illness

24
Q

What does dopamine affect? What problem is associated with it?

A

Affect:
1. motivation and reward
2. emotions
3. motor control
Problems:
- Schizophrenia
- Parkinson’s

25
Q

What does norepinephrine affect/problems?

A
  • mood states
  • attention
  • fight or flight
26
Q

What does seratonin affect?

A
  • patterns of sleep
  • mood levels
27
Q

What does GABA do?

A

Universal inhibitory NT
(anti-anxiety)

28
Q

What does Glutamate do?

A

Universal excitatory NT
(learning and memory)

29
Q

Match the columns
a. GABA 1. Alzheimer’s disease
b. 5-HT 2. Sleep pattern
c. DA 3. Parkinson’s disease
d. NE 4. Inhibitory NT
e. ACh 5. Attention

A

a. GABA –> 4. Inhibitory NT
b. 5-HT –> 2. Sleep pattern
(seratonin)
c. DA –> 3. Parkinson’s disease
d. NE –> 5. Attention
e. ACh –> 1. Alzheimer’s disease

30
Q

Some medications for Parkinson’s have been shown to affect emotions. What would that be
the case?

A

Parkinson’s medications increase dopamine all over the place, not just the specific pathway that needs it. This can elevate mood as well as increase likelihood of addiction in general