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Physiology Exam 1 > Neurophysiology 2 > Flashcards

Neurophysiology 2 Flashcards

1
Q

Why do graded potentials lose signal?

A

Resistance along axon

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2
Q

What is a length constant?

A

Distance over which graded electric potential shows a 63% drop in amplitude

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3
Q

What does rm stand for in the length constant?

A

resistance across

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4
Q

What does rl stand for in the length constant?

A

resistance along membrane

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5
Q

What happens the further a graded potential spreads along axon?

A

The further the location of initiation of action potential occurs

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6
Q

What is the safety factor?

A

Voltage change during action potential is 3X as large as needed to exceed threshold potential, extra depolarization

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7
Q

What does the safety factor cause?

A

Membrane ahead of action potential produces the next action potential

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8
Q

What is the domino effect of action potentials?

A

Action potential propogation

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9
Q

What is action potential propogation?

A

Activated patch of membrane’s current depolarizes adjacent patch, that one depolarizes next patch, because of refractory period flow travels in one direction

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10
Q

How can impulse propagation increase speed?

A

Increase axonal diameter

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11
Q

What size of axons have high conduction speed?

A

giant axons

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12
Q

What is the effect of increasing an axon’s radius?

A

Larger and increases speed of action potential conduction

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13
Q

What are two disadvantages of axons with large diameter?

A

Limits number of neurons that can be packed into the nervous system
Expensive to produce and maintain the level of cytoplasm

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14
Q

What can be an alternative to increasing axon diameter?

A

Electrical insulation via schwann cells

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15
Q

What cell type in the CNS is analogous to Schwann cells in the PNS?

A

Oligodendrocytes

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16
Q

What does myelin prevent?

A

Ions to move across membrane

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17
Q

What is the result of myelin not allowing ions to pass?

A

Push depolarization further down the axon

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18
Q

What is saltatory conduction?

A

Leapfrogging of action potentials from node to node along the axon

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19
Q

Can action potentials occur in the myelinated sections?

A

No, occur at the nodes

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20
Q

What type of disease if MS?

A

Demylinating disease

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21
Q

What happens with the loss of myelin?

A

Slows down conduction of action potentials

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22
Q

What are symptoms of MS?

A

Muscle weakness, fatigue, difficulty walking, loss of vision

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23
Q

What are the two ways to increase action potential speed?

A

Myelin
Increase axon diameter

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24
Q

What two things do propagation of action potentials depend on?

A

Passive properties of membranes
Extra depolarization

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25
Q

What is a synapse?

A

Connection between two neurons

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26
Q

What are two types of synapse?

A

Electrical
Chemical

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27
Q

What is an electrical synapse?

A

Electrical junction between 2 neurons allows current from action potential in one cell to spread into other and depolarize it

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28
Q

What is the function of electrical synapse?

A

Rapid transmission of signals, faster than chemical

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29
Q

When are electrical synapses used?

A

Synchronization of electrical activity in groups of neurons, heart, brain rhythms

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30
Q

What is important about the flow of information in electrical synapses?

A

Flow in both directions, no control of information

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31
Q

What is a chemical synapse?

A

Synapse using neurotransmitters

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32
Q

What are the steps of chemical synapse?

A

Depolarization of presynaptic terminal opens VGCaC
Ca cues the release of NT into synaptic cleft
Transmitter binds to receptors in postsynaptic membrane
Postsynaptic current causes excitatory or inhibitory potential

33
Q

What are two types of receptors for a neurotransmitter?

A

Ionotropic receptors
Metabotropic receptors

34
Q

What are ionotropic receptors associated with?

A

Ligand-activated ion channels

35
Q

What are metabotropic receptors associated with?

A

Signal and G proteins

36
Q

Do metabotropic or ionotropic receptors have faster responses?

A

Ionotropic

37
Q

How do ionotropic receptors work?

A

Neurotransmitter binds directly to ion channel

38
Q

How do metabotropic receptors work through Direct G-protein Coupling?

A

Neurotransmitter binds to receptor, activated G protein which opens or closes ion channel

39
Q

How do metabotropic receptors work through second messenger Coupling?

A

Neurotransmitter binds to receptor, activated G protein which activates or inhibits enzyme that produces second messenger that opens or closes ion channel

40
Q

What are the two types of metabotropic receptors?

A

Direct G-protein Coupling
second messenger Coupling

41
Q

Which type of chemical synapse utilizes small vesicles?

A

Ionotropic

42
Q

Which type of chemical synapse utilizes large vesicles?

A

metabotropic

43
Q

What is the active zone of a synapse?

A

Area of NT release

44
Q

What are the three steps of synaptic vesicle release?

A

Docking
Priming
Fusion

45
Q

What is docking?

A

Vesicles come close to membrane, within 30nm

46
Q

What is priming?

A

Can be induced to fuse with the plasma membrane

47
Q

What three ways can a vesicle be induced to fuse in a synapse?

A

Sustained depolarization
High K+ levels
Elevated Ca2+ levels

48
Q

What is fusion?

A

Vesicles fuse with plasma membrane to release NT into synaptic cleft

49
Q

What proteins regulate docking and Ca2+ induced fusion?

A

SNARE

50
Q

What are the three stores of neurotransmitters in CNS in order of percentage?

A

Reserve pool
Recycling pool
Readily releasable pool

51
Q

Where are NT released from with mild stimulation?

A

Readily-releasable pool
Small amount of recycling pool replenishes

52
Q

Where are NT released from with Strong stimulation?

A

Reserve pool

53
Q

What are3 ways Neurotransmitters are inactivated?

A

Returned to axon terminals
Enzymes inactivate them
Diffues out of synaptic cleft

54
Q

What is the most vulnerable step of neural signaling?

A

Synaptic transmission

55
Q

What are 3 diseases of synaptic transmission?

A

Parkinson’s
Schizophrenia
Depression

56
Q

What are 3 drugs that alter synaptic transmission?

A

Caffeine
Nicotine
Alcohol

57
Q

What is a disease where the body produces molecules to attack synaptic receptors?

A

Myasthenia gravis

58
Q

What are 2 results of receptor destruction?

A

Diminished excitatory response
Inability of muscle fibers to contract

59
Q

Why might synapses increase in size?

A

Forming more active zones, send a larger signal

60
Q

What is an EPSP?

A

Excitatory Postsynaptic Potential

61
Q

Binding of neurotransmitter to receptor on postsynaptic membrane leads to what?

A

Opening of postsynaptic channels

62
Q

What can pass through postsynaptic ion channel?

A

Both Na+ and K+

63
Q

What is the reversal potential?

A

Happens in chemical synapse when both Na and K move across postsynaptic membrane in opposite directions

64
Q

What is the reversal potential in excitatroy synapse?

A

More positive than threshold, results in AP

65
Q

What is the reversal potential in inhibitory synapse?

A

More negative than threshold, doesnt result in AP

66
Q

What is an IPSP?

A

Inhibitory postsynaptic potential

67
Q

What is temporal summation?

A

2 excitatory stimuli close together resulting in an AP in postsynaptic

68
Q

What is spatial summation?

A

2 stimuli from 2 neurons resulting in AP

69
Q

What is presynaptic inhibition?

A

Inhibitory synapse on top of a excitatory synapse

70
Q

What is a renshaw cell?

A

Controls over stimulation of muscle cells through presynaptic inhibition with glycine

71
Q

What is strychine?

A

Blocks glycine receptors, produces massive muscle contractions, fatal

72
Q

What type of potentials do ESPS/ISPS use?

A

Graded potentials

73
Q

What type of channels do ESPS/ISPS use?

A

Ligand gated

74
Q

What are two types of ACh receptor inhibitors?

A

Agonists- mimics
Antagonist- blocks

75
Q

What are two types of ACh receptors?

A

Nicotinic receptors
Muscarinic receptors

76
Q

What type of receptor is a nicotinic ACh receptor?

A

Ionotropic receptor

77
Q

What type of receptor is a muscarinic ACh receptor?

A

G-protein activation

78
Q

What are autoreceptors?

A

Decreases NT release and synthesis, negative feedback

79
Q

What are two types of gaseous NT’s?

A

Nitric oxide
Carbon monoxide

Physiology Exam 1 (5 decks)

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