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Neurology > Topic 3: APs, Synapses & NTs > Flashcards

Topic 3: APs, Synapses & NTs Flashcards

1
Q

When a neuron is not firing it is said to be ____

A

Resting

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2
Q

When a neuron is resting its cell membrane is ____

A

Polarized

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3
Q

A polarized membrane has an electrical gradient (difference) between the _____ of the cell membrane and the _____

A

Outside, Inside

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4
Q

The outside contains more ______ because a ‘pump’ pumps ____ out of the cell

A

Sodium (Na+), Na+

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5
Q

How long does the resting polarized neuron remain polarized ?

A

Until there is stimulus

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6
Q

The Na+ ion channels on the resting neuron’s membrane open suddenly when the stimulus reaches _____ and allow the Na+ that was on the ______ of the membrane to go rushing in

A

Threshold, outside

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7
Q

When the stimulus reaches threshold ___ goes in

A

Na+ ions

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8
Q

What is complete depolarization?

A

Complete depolarization of the axon results when threshold is reached and the neuron continues to open Na+ channels all along the cells membrane of the axon.

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9
Q

Wave depolarization is also called _____

A

Nerve impulse or the action potential

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10
Q

When is the neuron back to its normal polarized state?

A

After an appropriate amount of Na+ is pumped

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11
Q

What is the refractory period?

A

Refractory period is the time when the neuron is busy returning everything to the normal polarized (resting) state. It usually doesn’t respond to any incoming stimuli.

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12
Q

All axons are sheathed in myelin

A

False.

Many but not all axons are sheathed in myelin

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13
Q

The movement of ____ conduct APs along neuron cell membrane

A

Sodium

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14
Q

What is myelin made up of?

A

Myelin is composed of lipids (fat) and functions like rubber insulation around an electrical wire. It covers the length of the axon except for small nodes about 1mm. apart

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15
Q

What is it called when action potentials jump from Node to node ?

A

Saltatory Conduction

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16
Q

The speed of conduction along an axon depends on its ____ and whether it is ______

A

Diameter, myelinated

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17
Q

What is saltatory conduction?

A
  • Saltatory conduction increases nerve conduction velocity w/o having to dramatically increase axon diameter. Without it, conduction velocity would need large increases in axon diameter.
  • Saltatory conduction requires much less energy than continuous conduction b/c the sodium ‘pumps’ only need to operate at the nodes of Ranvier and not along the whole axon.
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18
Q

Demyelinating diseases such as _____ are often accompanied by debilitating fatigue.

A

Multiple Sclerosis

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19
Q

In _______, the impulse is propagated as a ____________ spreading along the axon

A

Unmyelinated, continuous wave of depolarization

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20
Q

In ______, the impulse ‘jumps’ from node to node, a faster and energy saving process called ________

A

Myelinated, Saltatory conduction

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21
Q

A typical synapse consists of :

A

1) Presynaptic neuron
2) Synaptic cleft
3) postsynaptic neuron

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22
Q

The ____ is where an AP is transmitted from one neuron to another neuron

A

Synapse

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23
Q

There are synapses between _____ and ____ and between ______ and ______

A

Neurons and muscles (NMJ), neurons and glands

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24
Q

A ______ is a chemical released by a presynaptic neuron

A

Neurotransmitter. It diffuses across the synaptic cleft to stimulate or inhibit the postsynaptic neuron.

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25
Q

Name the types of synapses:

A

Axon terminals can connect with :

1) dendrites of another neuron: axodendritic synapse (most common)
2) the cell body of another neuron: axiomatic synapse
3) the axon of another neuron: axoanonal synapse

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26
Q

When an AP reaches presynaptic terminal, vesicles containing neurotransmitters (NT) fuse with the neuron’s membrane and release their contents into the _______

A

synaptic cleft

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27
Q

______ are required for the fusion to take place

A

Calcium ions

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28
Q

An EPSP makes it _____ likely that an AP will continue in the postsynaptic neuron.

A

More likely.

Threshold of the postsynaptic neuron will most likely be reached

29
Q

An IPSP makes it ____ likely that an action potential will continue on in the post synaptic neuron

A

less likely.

Poles are further apart

30
Q

Frequent postsynaptic potentials at the same synapse occur in rapid succession. The effect of the first potential does not have time to dissipate and the succeeding potentials add to the previous ones

A

Temporal summation

E.g. Mom, mom, mommy .. what?

31
Q

Multiple excitatory signals to various postsynaptic sites

A

Spatial summation

32
Q

What is the All or None Law?

A

If the sum of all EPSPs and IPSPsr reaches threshold, an AP will result. however, if the neuron does not reach threshold, an AP will not occur. If it fires and the AP goes all the way to the end of the axon it is called All or None Law

33
Q

The change in the frequency of action potentials usually indicates ________

A

A change in the intensity of a stimulus

34
Q

A chemical that is released from the a neuron and transmits a nerve impulse from one neuron to another, muscle or organ or other tissue.

A

Neurotransmitter

35
Q

A NT ______ is a chemical that has the same effect on the postsynaptic neuron as the neurotransmitter does

A

agonist

36
Q

An ______ is a molecule that blocks the effect of a NT or its agonists

A

Antagonist

37
Q

Life-threatening depression of respiratory system is a side effect of _____

A

opioid overdose.

38
Q

When administered it allows an overdose victim to breathe normally

A

Naloxone, aka Narcan

e.x Often taken by musicians

39
Q

What is the most common inhibitory Neurotransmitter in the CNS

A

GABA - Gamma-aminobutyric acid

40
Q

Nerve cells fire often without this

A

GABA

41
Q

Low GABA activity is related to

A

Anxiety disorders, such as panic attacks, seizure disorders and cognitive impairment

42
Q

Supplement sold and promoted as a natural tranquilizer is ___

A

Valerian.

GABA taken as a supplement does not cross the BBB and works as a placebo.

43
Q

Examples of benzodiazepines are

A

Vallium and Librium

44
Q

Glutamate is the most common inhibitory neurotransmitter in the CNS

A

False. It is an excitatory NT

45
Q

This is involved in cognition, memory and learning

A

Glutamate

46
Q

Due to chronic inflammation, microglia can become ___

A

over activated (sensitized)

47
Q

____ use glutamate to destroy infected neurons, virus, and bacteria, but this can also cause large amounts of collateral damage to healthy neurons

A

Microglia (phagocytes of the CNS)

48
Q

Over activated microglia can result in a self-perpetuating cycle called ______

A

Reactive microgliosis .

An underlying mechanism of progressive neuron damage across numerous neurodegenerative diseases, regardless of the instigating stimuli.
E.g. NFL players experience this due to concussions

49
Q

____ deficit is linked to depression

A

Serotonin.

50
Q

a class of drugs that alleviate depression by increasing the length of time that serotonin stays in the synapse.

A

Selective Serotonin re-uptake inhibitors (SSRI)

Makes it more likely to bind to postsynaptic receptors.

51
Q

One well-known SSRI is _____

A

Prozac.

52
Q

An excess of dopamine in the limbic system and not enough in the cortex has been linked to ______

A

Paranoia and addiction (this is why addiction is a disease)

53
Q

An excess of dopamine in the frontal lobe _____

A

relieves pain and boosts feelings of pleasure

54
Q

Memory problems, Mov’t problems such as parkinson’s are a cause of _____

A

Shortage of dopamine

55
Q

Dopamine agonist drugs are linked to _____

A

Pathologic gambling, compulsive shopping, her impulse control disorders

56
Q

____ is secreted from the hypophysis. It is a hormone that also acts as a neurotransmitter in the brain

A

Oxytocin

57
Q

Oxytocin is thought to be released during ____

A

Hugging, touching and orgasm in both sexes.

58
Q

Two ways in which drugs modify synapse function

A
  1. Mimic the neurotransmitter (agonist)
    e. g morphine mimics endorphins in pain pathways
  2. Block re-uptake of neurotransmitter (antagonist)
    - Cocaine blocks the reuptake of dopamine
    - Prozac is a serotonin reuptake inhibitor
  3. Block enzyme pathways that degrade neurotransmitters
    - several anti-depressants block an enzyme that degrades serotonin, dopamine, epinephrine, and norepinephrine
59
Q

“PANS”

The neurotransmitter released at the postganglionic synapses is _________

A

Acetylcholine (Ach)

60
Q

Axons that release ACh are called ______

A

Cholinergic fibres

61
Q

Aka for cholinergic drugs

A

Parasympathomimetic drugs : because they produce effects that imitate parasympathetic nerve stimulation

62
Q

“SYNS”

The neurotransmitter released at the postganglionic synapses is _________

A

Norepinephrine aka noradrenalin

63
Q

Fibres that release norepinephrine are called _____

A

adrenergic fibres

64
Q

aka for adrenergic fibres

A

Sympathomimetic drugs: because they mimic effects similar to those produced by the sympathetic nervous system

65
Q

_____ drugs increase BP and HR and are useful in treating systemic trauma, including shock, and cardiac arrest

A

Adrenergic drugs

66
Q

Drugs that block or inhibit the release activity of NE known as

A

adrenergic blocking agents

67
Q

Aka for beta-adrenergic blocking agent

A

Beta-blocker : reduces symptoms connected with HT, cardiac arrhythmias and angina pectoris

68
Q

Why must people who take beta-blockers avoid caffeine, alcohol, and salty foods?

A

because the interaction of those substances and the drug can raise the heart rate and blood pressure

Neurology (2 decks)

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