Neuromuscular Physiology

Question 1

Central Nervous System (CNS) is composed of

Answer 1

Brain (including retinas)

Spinal cord

Intergrative/control centers

Question 2

Peripheral Nervous System (PNS) is composed of

Answer 2

Cranial nerves III-XII

Spinal Nerves

Question 3

Afferent Division is part of what Nervous System?

Answer 3

Central Nervous System (CNS)

Question 4

Afferent division is known as?

and what role does it play?

Answer 4

Sensory fibers;

Somatic and visceral neurons

Conducts impulses from receptors to CNS

Question 5

Efferent Division is part of what Nervous System?

Answer 5

Peripheral Nervous System (PNS)

Question 6

Efferent division is known as?

and what role does it play?

Answer 6

Motor fibers;

Motor neurons

Conducts impulses from the CNS to effectors

Question 7

Peripheral Nervous System is divided into what 2 systems?

Answer 7

Autonomic and Somatic Nervous System

Question 8

Role of Somatic Nervous System

Answer 8

Voluntary

Conducts impulses from the CNS to skeletal muscles

Question 9

Role of Autonomic Nervous System

Answer 9

Involuntary

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

Question 10

Autonomic Nervous System is divided into what 2 systems

Answer 10

Sympathetic and parasympathetic

Question 11

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

Answer 11

Motor Unit

Question 12

A motor unit is considered

Answer 12

the basic functional unit of the muscle

Question 13

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

Answer 13

as little as 4 to over 200

Question 14

a site where a motor neuron communicates with a muscle fiber

Answer 14

neuromuscular junction (NMJ)

Question 15

Motor axon terminal releases what neurotransmitter

Answer 15

acetylcholine

Question 16

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

Answer 16

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

Question 17

The neurotransmitter causes the effector cell to

Answer 17

change its membrane potential

Question 18

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

Answer 18

depolarization

Question 19

After the depolarization caused by the neurotransmitter what happens

Answer 19

the nerve impulse is transferred to the effector cell

Question 20

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

Answer 20

facilitation

Question 21

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

Answer 21

action potential spreads across the sarcolemma

Question 22

the spread of an action potential across the sarcolemma causes

Answer 22

the muscle fiber to contract

Question 23

how do neurons communicate with other neurons and with muscle cells

Answer 23

by releasing neurotransmitters

Question 24

neurotransmitters

Answer 24

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

Question 25

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

Answer 25

chemical and electrical gates

Question 26

Chemical gates are found? role? unlocked by?

Answer 26

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

Question 27

Electrical gates are found? role? opened by?

Answer 27

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)

Question 28

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

Answer 28

action potential

Question 29

Relative charge of membrane as a result of distribution of

Answer 29

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

Question 30

Neuron activations or excitations are known as

Answer 30

nerve impulses

Question 31

Nerve impulses are really waves of depolarization caused by

Answer 31

NA+ influx

Question 32

Muscle activation/excitation is caused by

Answer 32

NA+ influx

Question 33

The sympathetic system is

Answer 33

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.

Question 34

The parasympathetic system is

Answer 34

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.

Question 35

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

Answer 35

repolarize

Question 36

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

Answer 36

out in NA-K pump

Question 37

Repolarization requires energy in form of___.

Answer 37

ATP | No ATP No pumping

Question 38

Repolarization also occurs in

Answer 38

muscle

Question 39

Facilitation

Answer 39

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).

Question 40

Inhibition

Answer 40

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).

Question 41

Most Common Excitatory Neurotransmitters

Answer 41

Norepinephrine & Acetylcholine (nerve to muscle)

Question 42

Most Common Facilitory Neurotransmitters

Answer 42

Norepinephrine & Acetylcholine (in lower amounts)

Question 43

Another name for epinephrine

Answer 43

adrenalin

Question 44

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

Answer 44

inhibitors

Question 45

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

Answer 45

epinephrine facilitation and/or excitation

Question 46

Most common inhibitory neurotransmitter

Answer 46

GABA (gamma-aminobutyric acid)

Question 47

Drugs can also serve as

Answer 47

facilitators or inhibitors

Question 48

Drugs can cause facilitation by

Answer 48

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.

Question 49

Drugs can cause inhibition by

Answer 49

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.

Question 50

Spatial Summation

Answer 50

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

Question 51

Temporal Summation

Answer 51

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)

Question 52

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

Answer 52

rate coding

Question 53

when the muscle achieves maximal temporal summation, it has

Answer 53

reached tetanus

Question 54

Facilitation and inhibition are an integral part of

Answer 54

motor control and learning

Question 55

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

Answer 55

motor neuron spatial and/or temporal summation

Question 56

Coordination or the learning of the fine motor skills involves

Answer 56

inhibition and facilitation

Question 57

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

Answer 57

undesired motor units(fewer motor units=less force) allowing for one to 'groove' the desired movement pattern.

Question 58

Inhibition is used as a _____for_____

Answer 58

safety net for muscle groups

Question 59

Maximum voluntary contraction

Answer 59

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

Question 60

Maximum contraction

Answer 60

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

Question 61

Maximum contraction > maximum voluntary contraction because of

Answer 61

inhibition

Question 62

Nerve failure

Answer 62

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

Question 63

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

Answer 63

fatigue

Question 64

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

Answer 64

Neuron does not repolarize Neuron does not release neurotransmitter Branch point failure

Question 65

Why doesnt the neuron repolarize causing Nerve Failure?

Answer 65

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.

Question 66

Why doesnt the neuron release neurotransmitters causing Nerve Failure?

Answer 66

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.

Question 67

Why does the branch point fail causing Nerve Failure?

Answer 67

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.

Question 68

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

Answer 68

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!