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Block 5 > Phys: Propagation And Transmision Of Action Potentials And Synapses > Flashcards

Phys: Propagation And Transmision Of Action Potentials And Synapses Flashcards

1
Q

Schwann cells surround the nerve forming a…

A

Myelin sheath

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2
Q

Sphingomyelin decreases __________________ and _____________ 5000-fold

A

Membrane capacitance and ion flow

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3
Q

Myelin sheath is interrupted every 1-3mm by a….

A

Node of ranvier

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4
Q

Saltatory conduction

A

Action potentials are conducted from node to node but only OCCUR at the nodes

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5
Q

Why do APs only occur at the nodes?

A

-Na+ channels are concentrated there

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6
Q

APs an nodes allow for increased __________ and ______________

A

Velocity adn energy conservation

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7
Q

Velocity of AP in unmyelinated fibers:

A

0.25 m/s

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8
Q

Velocity of AP in myelinated fibers:

A

100 m/s

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9
Q

Multiple sclerosis is an…

A

Immune mediated inflammatory demyelinating disease of the CNS

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10
Q

Impulse transmission between cells occurs at a _____________

A

Synapse

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11
Q

Synapses are sites of…

A

Transmitting impulses from one cell (usually neuron) to another

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12
Q

Types of synapses:

A

-electrical synapse (gap junctions)
-chemical synapses(most common)
-excitatory
-inhibitory

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13
Q

Electrical synapses are…

A

Direct connections between cells which allows ions to flow between

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14
Q

Electrical synapses creates a ________________, which is a bunch of cells acting like one cell

A

Syncytium

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15
Q

Gap junctions are made up of…

A

Connexons that make holes in neighboring membranes

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16
Q

Where are coordinated contraction required?

A

-heart
-smooth muscle
-bladder

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17
Q

Electrical synapses are _____, no have no _____________

A

Fast, integration

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18
Q

Electrical synapses can travel…

A

In both directions or can be unidirectional

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19
Q

Electrotonic potential is proportional to…

A

Stimulus strength

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20
Q

Electrotonic potential is not propagated but…

A

Decremental with distance

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21
Q

Electrotonic potential exhibits ______________

A

Summation

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22
Q

Chemical synapse information is transported via….

A

Chemicals across synaptic cleft

23
Q

Chemical synapse experience ______________ flow

A

Unidirectional - presynaptic to postsynaptic

24
Q

_________ are released as neurotransmitters in chemical synapses

25
Neurotransmitters released from pre-synaptic cell by the action potential bind to…
Receptors on the post-synaptic cells
26
Activation of postsynaptic receptors alters __________________
Membrane potential
27
When an action potential reaches the terminal what opens? and what happens?
Voltage gated Ca channels open, Ca enters cell and causes exocytosis of vesicles containing neurotransmitters
28
Chemical synapse is _________ but allows for _____________
Slower, integration
29
When an action potential reaches the terminal what opens? and what happens?
Voltage gated Ca channels open, Ca enters cell and causes exocytosis of vesicles containing neurotransmitters
30
Binding of neurotransmitter to receptors allows:
-Neurotransmitters diffuse across the cleft from pre-post synaptic cell -bind to receptors on post-synaptic cell mem.
31
Effect of neurotransmitter binding on post-synaptic cell:
-alters membrane potential, can depolarize or hyperpolarize
32
Depolarization is __________ and makes it _____ likely for AP to fire
Excitatory, more
33
Hyperpolarization is _______________ and makes it ____likely for AP to fire
Inhibitory, less
34
Synapses are __________ structures
Dynamic
35
Synapses can increase and decrease in complexity and number depending on:
-use -experience
36
One-to-one synapses
One presynaptic to one postsynaptic
37
One-to-one synapse is used for:
-NMJ -conveys information
38
One-to-many synapse:
One presynaptic to more than one post-synaptic neuron
39
One-to-many synapses are used for:
-motor neurons in spinal cord -used to amplify a signal
40
Many-to-one synapse:
More than one presynaptic to one postsynaptic
41
Many-to-one synapse is used for:
-allows for integration of many signals -decides the proper response -very common
42
Excitatory post-synaptic potentials (EPSP)
-depolarize the cell towards threshold -usually result of opening Na or Ca channels depolarizing membrane to small degree (not enough for AP)
43
Inhibitory post-synaptic potentials (IPSPs):
-hyperpolarize cell membrane away from threshold -usually opening of Cl channels, increasing mem potential with negative charges
44
Excitatory neurotransmitters:
glutamate and acetylcholine
45
Inhibitory neurotransmitters
GABA and glycine
46
Current passing through an inhibitory interneuron elicits an…
Inhibitory IPSP in the flexor motor neuron
47
Usually each neuron is the post-synaptic cell for…
Numerous pre-synaptic cells (up to 10,000)
48
Signals have to be integrated in order to…
Make a decision about generation of new action potential
49
The time constant of a neuron determines…
The time course of the synaptic potential (how rapidly membrane transmits a charge)
50
The length constant of a neuron determines….
How much the depolarizing current is reduced as it spreads passively (how far initial depolarization travels through nerve before subsiding)
51
The time constant of the postsynaptic neuron affects the…
Amplitude of the depolarization caused by consecutive EPSPs produced by a single presynaptic neuron
52
If a second EPSP is elicited before the first decays…
The two potentials summate to induce an action potential
53
Spatial summation
Multiple inputs over a distance

Block 5 (46 decks)

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