Module 11 Flashcards

(41 cards)

0
Q

What does the motor unit consist of?

A

Alpha motor neurons and all fibers it innervates

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1
Q

What two ways is the skeletal muscle innervated?

A

Motor unit

Neuromuscular junction

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2
Q

What is the muscle to nerve ratio of the motor unit?

A

Small 1:5 in tongue muscles; small ratio if if needs to be more precise

Large 1:900 in leg; for gross movements

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3
Q

What is the neuromuscular junction?

A

Termination of a peripheral nerve fiber on skeletal muscles

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4
Q

Where is the motor end-plate?

A

Where the axon terminal synapses with the muscle fiber

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5
Q

Is the motor end plate part of the post synaptic membrane?

A

Yes!

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6
Q

What is the ratio of motor end plates per muscle fiber?

A

1:1; one end plate to EVERY fiber

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7
Q

What is the mV of the membrane potential in a neuro at rest?

A

-70 mV

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8
Q

What is membrane potential?

A

Measure of voltage between two points: the voltage across the membrane

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9
Q

How is MP (membrane potential) created?

A

Metabolic activity that:

Continuously diffuses potassium (K+)
and
SELECTIVE transport of substances through cell membrane using gating mechanisms

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10
Q

Inside of the cell there is a HIGH concentration of…

A
Anions (An-)
Potassium ions (K+)
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11
Q

Outside of the cell there is a HIGH concentration of…

A
Sodium ions (Na+)
Chloride ions (Cl-)
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12
Q

The resting cell is permeable and impermeable to what ions?

A

Impermeable to Na+

Permeable to K+ (so they leak out leaving An- which cause the cell to remain negative)

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13
Q

What is neuron excitability?

A

Allows neuron to respond to stimulus

Sends signals in electrical forms

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14
Q

What is it called when the signal is transmitted over a nerve fiber and the MP goes through a series of changes?

A

Action potential

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15
Q

What is an action potential?

A

Nerve impulse

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16
Q

How are AP elicited?

A

By anything that suddenly increases the permeability of the cell membrane to Na+

17
Q

What two types of stimulus can elicit an action potential?

A

Physical

Chemical

18
Q

How much membrane potential increase is needed to evoke an AP?

A

+10 mV or more

19
Q

How do transmission of neural signals occur?

A

Release of chemical stimulus (neurotransmitter)

Physical stimulus (pressure/pain/temperature)

20
Q

What is the difference between polarization, depolarization and repolarization?

A

Polarization- resting state

Depolarization- positive change

Repolarization- return to resting state

21
Q

How is AP conducted in myelinated axons?

A

Via saltatory conduction

Axon jumps from node to node (fasted conduction)

22
Q

How is AP conducted in unmyelinated axons?

A

General spread of AP

Gradual depolarization (slower conduction)

23
Q

How does AP Code information?

A

By response frequency

24
What is a refractory period?
Period IMMEDIATELY after the AP is triggered
25
Name the 2 components of a refractory period
Absolute refractory period | Relative refractory period
26
Is a refractory period shorter in smaller diameter neurons?
No!! It's shorter in longer diameter neurons
27
What is the absolute refractory period?
Neuron said to be hyperpolarized AP can not be generated Last for 2 msec
28
What is the relative refractory period?
Membrane is NOT fully repolarized | AP can be produced with a STRONG stimulus
29
what is the ALL or nothing principle?
Adequate stimulus fires to AP; it can not be partially fired
30
What two things can neurotransmitters influence the post-synaptic membrane to do?
Excite Or Inhibit
31
What's a generator potential?
Grades depolarization response
32
Is the GP an ALL OR NOTHING event?
NO! Relies on summation, collective effect of multiple arriving stimuli
33
What is the difference between the AP release and neurotransmitter release?
AP reaches terminal bouton neurotransmitter released from vesicles (acts on post synaptic membrane)
34
How do generator potential create an action potential?
Stimulus must reach the axon hillock and receive neural summation
35
What are the two types of neural summation for generator potential?
Temporal summation Spatial summation
36
What is a temporal summation?
Sub-threshold stimuli must occur within a critical period of time
37
What is a spatial summation?
Multiple stimuli converge on post synaptic membrane at the same time
38
How to generator potential code responses?
According to the intensity of the stimulus Weak stimulus; small potential (voltage change) Strong stimulus; large potential (voltage change)
39
What is an EPSP (excitatory post-synaptic potential)?
Excitation of receptor (soma/dendrite) Neurotransmitter partially depolarizes post synaptic membrane Generates GP CREATES likelihood of new AP
40
What is an IPSP (Inhibitory post-synaptic potential)?
Neurotransmitter hyperpolarizes the receptor (makes negative) Prevents neuron from firing Prevents development of GP DECREASE likelihood of new AP