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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
What is bidirectional signaling (electrical synapse)
When there are gap junctions between the presynapse neuron and the postsynaptic neuron/dendrite
26
What is unidirectional signaling (chemical synapse)
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
27
Stages of the chemical synapse
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
28
Neurotransmitter receptors can be classified as these two types
Ionotropic & metabotropic
29
What is an ionotropic neurotransmitter receptor
A receptor that allows ions to flow into and out of the neuron
30
What is a metabotropic neurotransmitter receptor`
Ligand-based channel that works with a neurotransmitter to elicit a change in the signal transduction pathway
31
What is neurotransmitter action determined by
1. Rate of release 2. Mode of action - excitatory vs. inhibitory 3. Rate of degredation - Neurotransmitter uptake and/or rapid degredation
32
When is acetylcholine stimulatory
When it binds to ionotropic acetylcholine receptors, such as in the muscle
33
When is acetylcholine inhibitory
When it binds to GPCRs->inhibits adenyl cyclase and maintain open K+ channels->hyperpolarization
34
What happens to acetylcholine in the synaptic cleft
1. Acetylcholine binds to postsynaptic receptors (cholinergic ion channels) 2. Acetylcholine-esterase (AChE) degrades Ach in the synaptic cleft to choline and acetate
35
What are the components of degraded ACetylcholine (Ach)
Choline & Acetate
36
What happens to Choline once it is degraded from Ach
Taken up by the presynaptic neuron to re-synthesize Ach
37
What happens to Acetate once it is degraded from Ach
Diffuses out of the synaptic cleft and into the blood stream
38
What is an example of an Acetylholine-esterase blocker
Nerve Gas ("Sarin")
39
How do AchE blockers work
Cause a buildup of Ach in the synaptic cleft at the neuromuscular junction
40
What is a consequence of AchE blockers
Causes sustained activation of the muscle, leading to desensitization, muscle paralysis, and death
41
What are two excitatory amino acid neurotransmitters
Glutamate & Aspartate
42
How do amino acid neurotransmitters work
Via ionotropic and metabotropic neurotransmitter receptors
43
What are two inhibitory amino acid neurotransmitter
Glycine & Gamma Amino Butyric Acid (GABA)
44
What are two types of GABA receptors
1. GABA-A: Ionotropic Cl- channel | 2. GABA-B: Metabotropic GPCR
45
What happens when GABA binds to GABA-A
GABA-A then causes an influx of Cl- ions, resulting in a hyperpolarization
46
What types of drugs inhibit epileptic and other types of seizures
Drugs that increase GABA receptor activation
47
What are biogenic amine neurotransmitters
Neurotransmitters with tyrosine derivatives, called Catecholamines or with tryptophan derivatives
48
Examples of biogenic amines
Dopamine and Norepinephrine
49
Precursor of norepinephrine
Dopamine
50
Where is dopamine found
In the midbrain
51
What is associated with dopamine deficiency
Parkinson's Disease
52
What is associated with excessive dopamine
Schizophrenia
53
Name 1 biogenic amine neurotransmitter with a tryptophan derivative
Serotonin
54
What does serotonin do
Affects sleep, mood, attention, and learning
55
Why does milk help you fall asleep
Because it has tryptophan in it
56
What is similar in structure and function with serotonin
LSD - a hallucinogenic drug
57
Biogenic amines are also called
Monoamines
58
How do monoamines act at the cellular level
Through GPCRs, activating second messenger systems
59
What happens after monoamines/biogenic amines activate their receptor
They are rapidly inactivated in the synaptic cleft or taken up by the presynaptic neuron for recycling
60
How does the presynaptic neuron recycle monoamines/biogenic amines
It metabolizes them with monoamine oxidase (MAO) both in the presynaptic neuron or in the synaptic cleft
61
What types of drugs are used as anti-depressants
Selective serotonin reuptake inhibitors (SSRI)
62
What are Parkinson's Disease patients usually treated with
Monoamine oxidase (MAO) inhibitors
63
How are neuropeptide neurotransmitter synthesized
Gene transcription/translation
64
How do neuropeptides act at the cellular level
Through GPCRs
65
What are three examples neuropeptides
1. Alpha melanoctye stimulating hormone (alpha-MSH) 2. Met-enkephalin 3. Gonadotropic-releasing hormone (GnRH)
66
What does (alpha-MSH) do
Acts within the hypothalamic feeding control circuit to suppress appetite
67
What does Met-enkephalin do
It is an endorphin and analgesic
68
Define analgesic
Inhibits perception of pain
69
What is GnRh responsible for
Stimulating LH & FSH, and promoting sexual behavior
70
What is a neuromodulator
Some mechanism that modulates the presynaptic neuron to elicit a response

Bio 225 (11 decks)

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