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Anatomy & Physiology > Neurotransmission > Flashcards

Neurotransmission Flashcards

1
Q

Na+K+ depolarization and repolarization can be corrected ________.

A

Quickly

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2
Q

The Na+K+ pump accounts for __% of the ATP requirement of the nervous system

A

70%

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3
Q

Action potentials are propagated without _________ _______ and are _________.

A

Decreasing amplitude

Irreversible

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4
Q

When are voltage-controlled Na+K+ pump channels are closed?

A

During the resting stage

When the current is -70mV

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5
Q

What Na+K+ channels are always open?

A

Leakage channels

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6
Q

What is the propagation rate of an unmyelinated fiber?

A

Up to 2m/s

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7
Q

What kinds of responses are mediated by unmyelinated fibers?

A

Mediates slower, visceral responses

E.g. Secretion of stomach acid and the dilation of the pupils

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8
Q

What is the propagation rate of a myelinated fiber?

A

Up to 120 m/s

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9
Q

What kinds of responses are mediated by myelinated fibers?

A

Involved where speed is more important

E.g. motor to skeletal muscle, sensory signals for vision and balance

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10
Q

In the cell, neurotransmitters are contained in?

A

Synaptic vesicles

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11
Q

A synaptic vesicle contains how many molecules of this substance?

A

10,000 ACh (acetylcholine)

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12
Q

Hos does ACh “leave” a synaptic vesicle? And what do the released molecules do?

A

ACh quickly diffuses out by exocytosis and crosses the narrow gap and binds to the receptor proteins in the postsynaptic membrane

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13
Q

What is the refractory period?

A

A period of resistance to depolarization

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14
Q

What is the absolute refractory period?

A

A period of no stimulation

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15
Q

Why can’t the cell respond to stimulus during the refractory period?

A

The Na+ gates are open, so they cannot reopen as a response to a new stimulus

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16
Q

What is the relative refractory period?

A

A time when only an unusually strong stimulus can depolarize the membrane to provide a new action potential
“Maybe” a signal can be sent -Beachy

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17
Q

Why can signals be retransmitted during the relative refractory period?

A

The K+ gates are open, so an unusually strong stimulus can provide a new action potential

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18
Q

What is EPSP?

A

Excitatory postsynaptic potentials
Any voltage change in a positive direction which makes a neuron more likely to fire
These are graded, not all-or-nothing

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19
Q

What is summation?

A

A type of EPSP where the action potentials can be “added” together

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20
Q

Where does EPSP occur?

A

In the axon hillock or “trigger zone”

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21
Q

In EPSP what is “added up”?

A

Presynaptic potential

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22
Q

What is temporal summation?

A

The signal hits the same place, one after another

A single synapse generates many EPSP

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23
Q

What is spatial summation?

A

The signal hits different places at the same time

EPSP come from several different synapses at the same time

24
Q

What is IPSP?

A

Inhibitory Postsynaptic Potentials

A hyperpolarizing of the postsynaptic membrane

25
Q

What happens to the cell membrane in IPSP?

A

Membrane is more negative, so it’s less likely to fire

26
Q

What molecules, and by what mechanism, does IPSP occur?

A

GABA and glycine both open chloride gates, so chloride ions flow in and hyperpolarize the postsynaptic membrane

27
Q

What is presynaptic inhibition?

A

1 presynaptic neuron suppresses another presynaptic neuron

28
Q

What is a neuromodulator?

A

Chemical messengers that have long-term effects on entire groups of neurons

29
Q

What is substance P?

A

Facilitates transmission of pain signals to the brain

30
Q

What is an endorphin?

A

Inhibits transmission of pain signals to the brain

31
Q

What are the two categorizations of axonal transport?

A

Slow and fast

32
Q

What is slow axonal transport?

A

0.5-10 mm/day, anterograde only

Transport from soma (cell body) to end bulb only

33
Q

What is fast axonal transport?

A

200-400 mm/day, both anterograde and retrograde

34
Q

What are two pathogens that attack humans via axonal transport?

A

tetanus: Bacterium, toxin from bacterium travels retrograde
rabies: virus, travels up axon (retrograde)

35
Q

What is the difference between flaccid and spastic paralysis?

A

Flaccid paralysis: eg loose arm

Spastic paralysis: ex rigid arm

36
Q

What is curare?

A

Arrowhead poison used in South America to hunt

37
Q

How does curare affect the body?

A

Blocks ACh receptors in muscle (mirrors ACh)

Flaccid paralysis in resp muscles, then death

38
Q

Is curare pre or postsynaptic?

A

Postsynaptic

39
Q

What is botulism?

A

Food poising caused by the botulin bacterium

Is the most potent known microbial toxin

40
Q

How does botulism affect the cell? And what kind of paralysis does it result in?

A

Blocks release of ACh @ presynaptic membrane

Flaccid paralysis

41
Q

What is polio?

A

A virus destroys the motor neurons

42
Q

Does polio result in flaccid or spastic paralysis?

A

Flaccid paralysis

43
Q

What is tetrodotoxin?

A

Founnd in the skin and some organs of the puffer fish

44
Q

What is the mechanism of tetrodotoxin?

A

A highly specific Na channel blocker.

Nerve fiber cannot generate and propagate an action potential

45
Q

Is tetrodotoxin pre or postsynaptic? What kind of paralysis does it cause?

A

Postsynaptic

Flaccid paralysis

46
Q

What is tetanus?

A

Toxin is tetanospasmin

47
Q

What is the mechanism of tetanus?

A

Toxin blocks glycine release and this causes overstimulation (hyperpolarization)

48
Q

What kind of paralysis comes from tetanus?

A

Spastic paralysis

49
Q

What is MG?

A

Myasthenia gravis

Autoimmune disease of generalized muscle weakness

50
Q

What is the mechanism of MG?

A

Muscle fibers become less and less susceptible to ACh

51
Q

Is MG pre or postsynaptic?

A

Postsynaptic (the receptors on muscle fibers are destroyed)

52
Q

What is used to treat MG and how does it work?

A

Use cholinesterase inhibitors to inhibit AChE, in the hope that more ACh can stimulate`

53
Q

What is MS?

A

Multiple sclerosis
Degenerative disorder of myelin sheaths
Breakdown of myelin in CNS, replaced with hardened scar tissue

54
Q

MS is a ________ disease which results in the loss of ______ function over time.

A

Progressive

Nerve

55
Q

What are some symptoms of MS?

A

Doublevision, blindness, speech defects, tremors and numbness

56
Q

What kind of synapse uses ACh?

A

Cholinergic

57
Q

What kind of synapse uses NE?

A

Adrenogenic

Anatomy & Physiology (14 decks)

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