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Neuroanatomy > Module 11 > Flashcards

Module 11 Flashcards

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
Q

What is a refractory period?

A

Period IMMEDIATELY after the AP is triggered

25
Q

Name the 2 components of a refractory period

A

Absolute refractory period

Relative refractory period

26
Q

Is a refractory period shorter in smaller diameter neurons?

A

No!! It’s shorter in longer diameter neurons

27
Q

What is the absolute refractory period?

A

Neuron said to be hyperpolarized
AP can not be generated
Last for 2 msec

28
Q

What is the relative refractory period?

A

Membrane is NOT fully repolarized

AP can be produced with a STRONG stimulus

29
Q

what is the ALL or nothing principle?

A

Adequate stimulus fires to AP; it can not be partially fired

30
Q

What two things can neurotransmitters influence the post-synaptic membrane to do?

A

Excite
Or
Inhibit

31
Q

What’s a generator potential?

A

Grades depolarization response

32
Q

Is the GP an ALL OR NOTHING event?

A

NO! Relies on summation, collective effect of multiple arriving stimuli

33
Q

What is the difference between the AP release and neurotransmitter release?

A

AP reaches terminal bouton

neurotransmitter released from vesicles (acts on post synaptic membrane)

34
Q

How do generator potential create an action potential?

A

Stimulus must reach the axon hillock and receive neural summation

35
Q

What are the two types of neural summation for generator potential?

A

Temporal summation

Spatial summation

36
Q

What is a temporal summation?

A

Sub-threshold stimuli must occur within a critical period of time

37
Q

What is a spatial summation?

A

Multiple stimuli converge on post synaptic membrane at the same time

38
Q

How to generator potential code responses?

A

According to the intensity of the stimulus

Weak stimulus; small potential (voltage change)

Strong stimulus; large potential (voltage change)

39
Q

What is an EPSP (excitatory post-synaptic potential)?

A

Excitation of receptor (soma/dendrite)
Neurotransmitter partially depolarizes post synaptic membrane
Generates GP
CREATES likelihood of new AP

40
Q

What is an IPSP (Inhibitory post-synaptic potential)?

A

Neurotransmitter hyperpolarizes the receptor (makes negative)

Prevents neuron from firing

Prevents development of GP
DECREASE likelihood of new AP

Neuroanatomy (19 decks)

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