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Bio 225 > Neurobiology 3 > Flashcards

Neurobiology 3 Flashcards

1
Q

Where is the action potential located

A

only generated in the axon

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2
Q

What property of action potentials details its ‘entirety’ nature

A

All or none

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3
Q

What is required for action potential to fire

A

Threshold stimulus

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4
Q

What is constant about the action potential

A

Amplitude

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5
Q

What can an action potential not fire

A

Refractory period

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6
Q

What ensures unidirectional transmission of the action potential along an axon

A

The inability for an action potential to fire during the refractory period

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7
Q

Is the action potential propagated with or without decrement

A

Without decrement

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8
Q

What are the name of the two types of refractory periods

A
  1. Absolute refractory period

2. Relative refractory period

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9
Q

What is the absolute refractory period

A

When the axon is incapable of generating a new action potential

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10
Q

What is relative refractory period

A

This is when only very strong stimuli can generate a new action potential

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11
Q

What stages does the absolute refractory period consist of

A

Action potential up and down (but not the undershot stage)

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12
Q

What stages does the relative refractory period consist of

A

The undershoot stage when the membrane potential is lower than the resting potential

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13
Q

What is electrotonic conduction

A

This is the process of a local depolarization spreading the action potential passively through the axon

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14
Q

What ensures the directional propagation of the action potential

A

The inactivation gates of the voltage-gated Na+ channels

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15
Q

How can you tell how strong a stimulus is

A

By measuring the action potential frequency

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16
Q

What are two strategies that are utilized by neurons to maximize action potential conduction

A
  1. Large diameter axons

2. Myelin Sheaths

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17
Q

Properties of having a large diameter axon:

A

Very low intracellular resistance to current flow (so current flows far and fast)

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18
Q

How do myelin sheaths promote action potential speed

A

By insulating the able/axon to favor speed of conductance

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19
Q

What is saltatory conduction

A

When a nerve impulse (the action potential) skips down the axon due to Schwann cells. This results in faster propagatioin

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20
Q

What are Nodes of Ranvier

A

Parts of the axon where myelin is absent, but Na+ and K+ channels are present. Slow

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21
Q

What are internode regions

A

Regions of the axon where there is myelination. No Na+ and K+ channels are present

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22
Q

What is Multiple Sclerosis (MS)

A

An autoimmune disorder where the immune system attacks myelin-forming cells

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23
Q

What is a consequence of Multiple Sclerosis (MS)

A

The neurons have slower propagation of the electrical signal and this decreases muscular control and results in paralysis

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24
Q

Where do neurons transmit their signals

A

At electrical or chemical synapses

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25
Q

What is bidirectional signaling (electrical synapse)

A

When there are gap junctions between the presynapse neuron and the postsynaptic neuron/dendrite

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26
Q

What is unidirectional signaling (chemical synapse)

A

When an electrical signal stimulates neurotransmitter release from the presynaptic neuron to bind to a receptor in the postsynaptic neuron, generating a new electric signal in the postsynaptic neuron

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27
Q

Stages of the chemical synapse

A
  1. Action potential arrives at axon terminal
  2. Voltage-gated Ca 2+ channels open
  3. Ca 2+ enters the presynaptic terminal
  4. Ca 2+ signals vesicles
  5. Vesicles move to the membrane
  6. Vesicles secrete neurotransmitters by exocytosis
  7. Neurotransmitters diffuses and binds to postsynaptic terminal receptors
  8. Binding activates signal transduction pathway
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28
Q

Neurotransmitter receptors can be classified as these two types

A

Ionotropic & metabotropic

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29
Q

What is an ionotropic neurotransmitter receptor

A

A receptor that allows ions to flow into and out of the neuron

30
Q

What is a metabotropic neurotransmitter receptor`

A

Ligand-based channel that works with a neurotransmitter to elicit a change in the signal transduction pathway

31
Q

What is neurotransmitter action determined by

A
  1. Rate of release
  2. Mode of action - excitatory vs. inhibitory
  3. Rate of degredation - Neurotransmitter uptake and/or rapid degredation
32
Q

When is acetylcholine stimulatory

A

When it binds to ionotropic acetylcholine receptors, such as in the muscle

33
Q

When is acetylcholine inhibitory

A

When it binds to GPCRs->inhibits adenyl cyclase and maintain open K+ channels->hyperpolarization

34
Q

What happens to acetylcholine in the synaptic cleft

A
  1. Acetylcholine binds to postsynaptic receptors (cholinergic ion channels)
  2. Acetylcholine-esterase (AChE) degrades Ach in the synaptic cleft to choline and acetate
35
Q

What are the components of degraded ACetylcholine (Ach)

A

Choline & Acetate

36
Q

What happens to Choline once it is degraded from Ach

A

Taken up by the presynaptic neuron to re-synthesize Ach

37
Q

What happens to Acetate once it is degraded from Ach

A

Diffuses out of the synaptic cleft and into the blood stream

38
Q

What is an example of an Acetylholine-esterase blocker

A

Nerve Gas (“Sarin”)

39
Q

How do AchE blockers work

A

Cause a buildup of Ach in the synaptic cleft at the neuromuscular junction

40
Q

What is a consequence of AchE blockers

A

Causes sustained activation of the muscle, leading to desensitization, muscle paralysis, and death

41
Q

What are two excitatory amino acid neurotransmitters

A

Glutamate & Aspartate

42
Q

How do amino acid neurotransmitters work

A

Via ionotropic and metabotropic neurotransmitter receptors

43
Q

What are two inhibitory amino acid neurotransmitter

A

Glycine & Gamma Amino Butyric Acid (GABA)

44
Q

What are two types of GABA receptors

A
  1. GABA-A: Ionotropic Cl- channel

2. GABA-B: Metabotropic GPCR

45
Q

What happens when GABA binds to GABA-A

A

GABA-A then causes an influx of Cl- ions, resulting in a hyperpolarization

46
Q

What types of drugs inhibit epileptic and other types of seizures

A

Drugs that increase GABA receptor activation

47
Q

What are biogenic amine neurotransmitters

A

Neurotransmitters with tyrosine derivatives, called Catecholamines or with tryptophan derivatives

48
Q

Examples of biogenic amines

A

Dopamine and Norepinephrine

49
Q

Precursor of norepinephrine

A

Dopamine

50
Q

Where is dopamine found

A

In the midbrain

51
Q

What is associated with dopamine deficiency

A

Parkinson’s Disease

52
Q

What is associated with excessive dopamine

A

Schizophrenia

53
Q

Name 1 biogenic amine neurotransmitter with a tryptophan derivative

A

Serotonin

54
Q

What does serotonin do

A

Affects sleep, mood, attention, and learning

55
Q

Why does milk help you fall asleep

A

Because it has tryptophan in it

56
Q

What is similar in structure and function with serotonin

A

LSD - a hallucinogenic drug

57
Q

Biogenic amines are also called

A

Monoamines

58
Q

How do monoamines act at the cellular level

A

Through GPCRs, activating second messenger systems

59
Q

What happens after monoamines/biogenic amines activate their receptor

A

They are rapidly inactivated in the synaptic cleft or taken up by the presynaptic neuron for recycling

60
Q

How does the presynaptic neuron recycle monoamines/biogenic amines

A

It metabolizes them with monoamine oxidase (MAO) both in the presynaptic neuron or in the synaptic cleft

61
Q

What types of drugs are used as anti-depressants

A

Selective serotonin reuptake inhibitors (SSRI)

62
Q

What are Parkinson’s Disease patients usually treated with

A

Monoamine oxidase (MAO) inhibitors

63
Q

How are neuropeptide neurotransmitter synthesized

A

Gene transcription/translation

64
Q

How do neuropeptides act at the cellular level

A

Through GPCRs

65
Q

What are three examples neuropeptides

A
  1. Alpha melanoctye stimulating hormone (alpha-MSH)
  2. Met-enkephalin
  3. Gonadotropic-releasing hormone (GnRH)
66
Q

What does (alpha-MSH) do

A

Acts within the hypothalamic feeding control circuit to suppress appetite

67
Q

What does Met-enkephalin do

A

It is an endorphin and analgesic

68
Q

Define analgesic

A

Inhibits perception of pain

69
Q

What is GnRh responsible for

A

Stimulating LH & FSH, and promoting sexual behavior

70
Q

What is a neuromodulator

A

Some mechanism that modulates the presynaptic neuron to elicit a response

Bio 225 (11 decks)

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