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(Basic Exercise Physiology) > Neuromuscular Physiology > Flashcards

Neuromuscular Physiology Flashcards

1
Q

Central Nervous System (CNS) is composed of

A

Brain (including retinas)

Spinal cord

Intergrative/control centers

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2
Q

Peripheral Nervous System (PNS) is composed of

A

Cranial nerves III-XII

Spinal Nerves

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3
Q

Afferent Division is part of what Nervous System?

A

Central Nervous System (CNS)

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4
Q

Afferent division is known as?

and what role does it play?

A

Sensory fibers;

Somatic and visceral neurons

Conducts impulses from receptors to CNS

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5
Q

Efferent Division is part of what Nervous System?

A

Peripheral Nervous System (PNS)

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6
Q

Efferent division is known as?

and what role does it play?

A

Motor fibers;

Motor neurons

Conducts impulses from the CNS to effectors

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7
Q

Peripheral Nervous System is divided into what 2 systems?

A

Autonomic and Somatic Nervous System

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8
Q

Role of Somatic Nervous System

A

Voluntary

Conducts impulses from the CNS to skeletal muscles

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9
Q

Role of Autonomic Nervous System

A

Involuntary

Conducts impulses from the CNS to cardiac muscle, smooth muscles, and glands

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10
Q

Autonomic Nervous System is divided into what 2 systems

A

Sympathetic and parasympathetic

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11
Q

The motor neuron and all the muscle cells it services is called

A

Motor Unit

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12
Q

A motor unit is considered

A

the basic functional unit of the muscle

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13
Q

Each motor neuron synapses is made up of how many muscle cells

A

as little as 4 to over 200

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14
Q

a site where a motor neuron communicates with a muscle fiber

A

neuromuscular junction (NMJ)

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15
Q

Motor axon terminal releases what neurotransmitter

A

acetylcholine

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16
Q

once acetylcholine is released from the motor axon where does it go?

A

travels across a synaptic cleft and bind to receptors on a muscle fiber

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17
Q

The neurotransmitter causes the effector cell to

A

change its membrane potential

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18
Q

The change of the effector cell to its membrane potential is known as

A

depolarization

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19
Q

After the depolarization caused by the neurotransmitter what happens

A

the nerve impulse is transferred to the effector cell

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20
Q

The transfer of the nerve impulse to the effector cell is known as

A

facilitation

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21
Q

If a membrane potential is increased to reach its threshold what occurs

A

action potential spreads across the sarcolemma

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22
Q

the spread of an action potential across the sarcolemma causes

A

the muscle fiber to contract

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23
Q

how do neurons communicate with other neurons and with muscle cells

A

by releasing neurotransmitters

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24
Q

neurotransmitters

A

chemicals released by a neuron which cause either excitation, facilitation, or inhibition

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25
Q

Nerve and muscle cells have two types of NA+ gates/channels which allows NA+ entry (influx) and depolarization

A

chemical and electrical gates

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26
Q

Chemical gates are found? role? unlocked by?

A

are the least numerous

found mainly in the nerve cell body and dendrites

found in muscles at the nerve synapse

opened or unlocked by the neurotransmitters

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27
Q

Electrical gates are found? role? opened by?

A

are the most numerous

found mainly in the neuronal axons

found distal to synapses in muscle cells

opened when the resting membrane potential exceeds a specific threshold voltage (usually around 60mV)

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28
Q

the opening of the electrical gates that causes the necessary level/wave depolarization is called

A

action potential

29
Q

Relative charge of membrane as a result of distribution of

A

Sodium (NA+)(chloride(Cl-), potassium(K+) and large intracellular anions (A-)

30
Q

Neuron activations or excitations are known as

A

nerve impulses

31
Q

Nerve impulses are really waves of depolarization caused by

A

NA+ influx

32
Q

Muscle activation/excitation is caused by

A

NA+ influx

33
Q

The sympathetic system is

A

its fight or the flight system and its nerves direct more blood to the muscles whereas decreases blood supply to the gut.It increases the heart rate and blood pressure and also activates the body’s mechanisms to provide immediate energy to face the stressful state.So this system utilizes the body’s energy resources just to prepare it for some upcoming stressful state.

34
Q

The parasympathetic system is

A

its the rest and digest system.It increases the blood supply to gut and increases the digestion.So it tries to restore the body’s energy sources.

35
Q

Before another impulse can be sent down an axon, the nerve must

A

repolarize

36
Q

During repolarization, the NA+ goes ____ and the K+ goes ____. Which are switch via the____.

A

out

in

NA-K pump

37
Q

Repolarization requires energy in form of___.

A

ATP

No ATP No pumping

38
Q

Repolarization also occurs in

A

muscle

39
Q

Facilitation

A

Raising the the resting membrane potential above the normal potential, thereby increasing the likelihood that succeeding neurotransmitter releases will cause the potential to exceed the threshold. This enhances the chances of the neuron firing and activating the target. (i.e. greater chance of muscle excitation by facilitating the motor neuron).

40
Q

Inhibition

A

Lowering the resting membrane potential below the normal potential, thereby decreasing the likelihood of reaching the threshold. This usual prevents the neuron from activating its target. (i.e. prevents motor neuron from activating the motor unit).

41
Q

Most Common Excitatory Neurotransmitters

A

Norepinephrine & Acetylcholine (nerve to muscle)

42
Q

Most Common Facilitory Neurotransmitters

A

Norepinephrine & Acetylcholine (in lower amounts)

43
Q

Another name for epinephrine

A

adrenalin

44
Q

In some parts of the body norepinephrine and acetylcholine will act s

A

inhibitors

45
Q

Norepinephrine packs a double wallop by activation the adrenal medulla to release____, which can also cause____.

A

epinephrine

facilitation and/or excitation

46
Q

Most common inhibitory neurotransmitter

A

GABA (gamma-aminobutyric acid)

47
Q

Drugs can also serve as

A

facilitators or inhibitors

48
Q

Drugs can cause facilitation by

A

A. Opening chemically gated channels
B. Increased concentrations of NT
1. Block the breakdown of ACH. If ACH doesn’t get removed the signal keeps being sent.
2. Stop this re-uptake Norepinephrine. Once again is NT is not removed from its binding site it will keep sending its messege. (e.g. cocaine)
C. Increased epinephrine production.

49
Q

Drugs can cause inhibition by

A

A. Block the release of either the neurotransmitter or epinephrine
B. Block the neurotransmitter binding siit
C. Block the channel so that Na+ or K+ cannot pass through.
D. Accelerated removal of the neurotransmitter from the synapse.

50
Q

Spatial Summation

A

Neurotransmitter release from more than one neuron is necessary to cause excitation.
(insufficient release yields facilitation)

51
Q

Temporal Summation

A

Altering the frequency of a nerve firing (i.e. neurotransmitter release) to ensure sufficient amounts to cause depolarization. This is most often seen in nerve excitation of muscle. (i.e the more rapid the nerve fires the greater the force output of the muscle)

52
Q

When temporal summation occurs in skeletal muscles, it is usually referred to as

A

rate coding

53
Q

when the muscle achieves maximal temporal summation, it has

A

reached tetanus

54
Q

Facilitation and inhibition are an integral part of

A

motor control and learning

55
Q

Facilitation and inhibition can operate on the ______ or they can influence______

A

motor neuron

spatial and/or temporal summation

56
Q

Coordination or the learning of the fine motor skills involves

A

inhibition and facilitation

57
Q

Coordination or the learning of fine motor skills involves inhibition by ______ and facilitation by______.

A

undesired motor units(fewer motor units=less force)

allowing for one to ‘groove’ the desired movement pattern.

58
Q

Inhibition is used as a _____for_____

A

safety net for muscle groups

59
Q

Maximum voluntary contraction

A

the maximum amount of weight (1 RM) a muscle group can lift when under conscious control.

60
Q

Maximum contraction

A

the maximum amount of weight (1 RM) a muscle group can lift under electrical stimulation.

61
Q

Maximum contraction > maximum voluntary contraction because of

A

inhibition

62
Q

Nerve failure

A

when a nerve fails to activate its target through some mechanism other than inhibition

63
Q

When the nerve fails to activate a muscle, then the condition is generally referred to as

A

fatigue

64
Q

what are the 3 main causes of Nerve failure (aka Neuronal Based Fatigue)

A

Neuron does not repolarize

Neuron does not release neurotransmitter

Branch point failure

65
Q

Why doesnt the neuron repolarize causing Nerve Failure?

A

Repolarization requires an active Na-K pump. The Na-K pump needs energy (ATP) to operate. Therefore, if the ATP is “used up”, the neuron can not repolarize and hence fails.
NOTE: This condition can be identified by finding high post-exercise serum potassium (K+) levels.
NOTE: This condition usually will occur with high stimulation frequencies or rapid temporal summation.

66
Q

Why doesnt the neuron release neurotransmitters causing Nerve Failure?

A

Neurotransmitter is made and stored in packets in the synaptic end bulb. If neurotransmitter release occurs faster than the rate at which it is being made, the neuron will eventually “run out” of neurotransmitter. With no transmitter, even if the neuron depolarizes, the target will not be activated.
NOTE: This condition usually will occur with high stimulation frequencies or rapid temporal summation.

67
Q

Why does the branch point fail causing Nerve Failure?

A

Most neuronal axons have branches of varying lengths (esp. motor neurons). When a neuron is being stimulated at high frequencies, some of the longer branches can not repolarize as fast as the rest of the axon. Thus when the neuron is activated again, some of the branches can’t depolarize because they have not repolarized yet. Hence, failure occurs at the point of branching. When this occurs, fatigue is manifested by a failure of a single motor unit’s individual muscles cells to contract.
NOTE: This condition usually will occur with high stimulation frequencies or rapid temporal summation.

68
Q

How does one prevent nerve failure (Neuronal Based Fatigue)?

A

Reduce the stimulation frequency of each neuron.

PROBLEM: The principle of Rate Coding indicates that if one decreases stimulation frequency, then muscle force output also decreases. Decreased Force = Fatigue!

(Basic Exercise Physiology) (3 decks)

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