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Physiology Exam 1 > Neurophysiology 2 > Flashcards

Neurophysiology 2 Flashcards

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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
What is a synapse?
Connection between two neurons
26
What are two types of synapse?
Electrical Chemical
27
What is an electrical synapse?
Electrical junction between 2 neurons allows current from action potential in one cell to spread into other and depolarize it
28
What is the function of electrical synapse?
Rapid transmission of signals, faster than chemical
29
When are electrical synapses used?
Synchronization of electrical activity in groups of neurons, heart, brain rhythms
30
What is important about the flow of information in electrical synapses?
Flow in both directions, no control of information
31
What is a chemical synapse?
Synapse using neurotransmitters
32
What are the steps of chemical synapse?
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
What are two types of receptors for a neurotransmitter?
Ionotropic receptors Metabotropic receptors
34
What are ionotropic receptors associated with?
Ligand-activated ion channels
35
What are metabotropic receptors associated with?
Signal and G proteins
36
Do metabotropic or ionotropic receptors have faster responses?
Ionotropic
37
How do ionotropic receptors work?
Neurotransmitter binds directly to ion channel
38
How do metabotropic receptors work through Direct G-protein Coupling?
Neurotransmitter binds to receptor, activated G protein which opens or closes ion channel
39
How do metabotropic receptors work through second messenger Coupling?
Neurotransmitter binds to receptor, activated G protein which activates or inhibits enzyme that produces second messenger that opens or closes ion channel
40
What are the two types of metabotropic receptors?
Direct G-protein Coupling second messenger Coupling
41
Which type of chemical synapse utilizes small vesicles?
Ionotropic
42
Which type of chemical synapse utilizes large vesicles?
metabotropic
43
What is the active zone of a synapse?
Area of NT release
44
What are the three steps of synaptic vesicle release?
Docking Priming Fusion
45
What is docking?
Vesicles come close to membrane, within 30nm
46
What is priming?
Can be induced to fuse with the plasma membrane
47
What three ways can a vesicle be induced to fuse in a synapse?
Sustained depolarization High K+ levels Elevated Ca2+ levels
48
What is fusion?
Vesicles fuse with plasma membrane to release NT into synaptic cleft
49
What proteins regulate docking and Ca2+ induced fusion?
SNARE
50
What are the three stores of neurotransmitters in CNS in order of percentage?
Reserve pool Recycling pool Readily releasable pool
51
Where are NT released from with mild stimulation?
Readily-releasable pool Small amount of recycling pool replenishes
52
Where are NT released from with Strong stimulation?
Reserve pool
53
What are3 ways Neurotransmitters are inactivated?
Returned to axon terminals Enzymes inactivate them Diffues out of synaptic cleft
54
What is the most vulnerable step of neural signaling?
Synaptic transmission
55
What are 3 diseases of synaptic transmission?
Parkinson's Schizophrenia Depression
56
What are 3 drugs that alter synaptic transmission?
Caffeine Nicotine Alcohol
57
What is a disease where the body produces molecules to attack synaptic receptors?
Myasthenia gravis
58
What are 2 results of receptor destruction?
Diminished excitatory response Inability of muscle fibers to contract
59
Why might synapses increase in size?
Forming more active zones, send a larger signal
60
What is an EPSP?
Excitatory Postsynaptic Potential
61
Binding of neurotransmitter to receptor on postsynaptic membrane leads to what?
Opening of postsynaptic channels
62
What can pass through postsynaptic ion channel?
Both Na+ and K+
63
What is the reversal potential?
Happens in chemical synapse when both Na and K move across postsynaptic membrane in opposite directions
64
What is the reversal potential in excitatroy synapse?
More positive than threshold, results in AP
65
What is the reversal potential in inhibitory synapse?
More negative than threshold, doesnt result in AP
66
What is an IPSP?
Inhibitory postsynaptic potential
67
What is temporal summation?
2 excitatory stimuli close together resulting in an AP in postsynaptic
68
What is spatial summation?
2 stimuli from 2 neurons resulting in AP
69
What is presynaptic inhibition?
Inhibitory synapse on top of a excitatory synapse
70
What is a renshaw cell?
Controls over stimulation of muscle cells through presynaptic inhibition with glycine
71
What is strychine?
Blocks glycine receptors, produces massive muscle contractions, fatal
72
What type of potentials do ESPS/ISPS use?
Graded potentials
73
What type of channels do ESPS/ISPS use?
Ligand gated
74
What are two types of ACh receptor inhibitors?
Agonists- mimics Antagonist- blocks
75
What are two types of ACh receptors?
Nicotinic receptors Muscarinic receptors
76
What type of receptor is a nicotinic ACh receptor?
Ionotropic receptor
77
What type of receptor is a muscarinic ACh receptor?
G-protein activation
78
What are autoreceptors?
Decreases NT release and synthesis, negative feedback
79
What are two types of gaseous NT's?
Nitric oxide Carbon monoxide

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