Neuromuscular System and Exercise Flashcards Preview

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Flashcards in Neuromuscular System and Exercise Deck (35)
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1
Q

What is the neuromuscular system

A

the interaction between the nervous system and the muscles.

2
Q

What happens when there is a voluntary decision to move?

A

Efferent nerve impulses are sent

3
Q

What is the basic functional unit of movement?

A

Motor neuron

4
Q

What is in a motor unit?

A

Anterior motor neuron

Muscle fibers it innervates

5
Q

What is a motor neuron?

A

Efferent nerve and is relatively large in diameter
leads to neuromuscular junstion
Myelinated thus provides fast conductivity

6
Q

What is a motor units?

A

Includes the interface and muscle fiber
Site of acetylcholine release = change in NA2+ and K+ permeability
Initiating depolarization and contraction

7
Q

How can we study motor units?

A

1) Electromyography (surface and intramuscular)
- Quality and quantity of electrical activity
2) Muscle biopsy
- Removal and analysis of a small portion of muscle
- Directly measures fibers
3) Force/Power Output Device
- Measures force, power, torque, angular velocity
4) Other imaging devices

8
Q

What are the classifications of the 3 primary motor units?

A
Fast Fatiguable
-high force
-thickest
-fatigue
Fast fatigue resistance
-fast
-mod force
-thick
Slow twitch
-low force
-fatigue resistance
9
Q

What is the nerve to muscle fibre ratio definition?

A

A single motor neuron and the number of muscle fibres stimulated

10
Q

What is gross movement?

A

Muscles involved a higher muscle fiber to nerve ratio (gastroc 1:1776)

11
Q

What is precise movement?

A

Fine movements have a lower muscle fiber to nerve ratio

eye 10:1

12
Q

What is Hennman’s size principle?

A

Small neurons fire first

Need to be at or above 60% of MVC to recruit fast fatigue

13
Q

What motor units are recruited first?

A

slow motor units for both power and endurance movements

-Slow have a lower recruitment threshold (depolarize quicker)

14
Q

What accounts for force production during fast velocity exercise?

A

Fast fatigue and fast fatigue resistant

15
Q

What are the fiber type classification?

A
Type I (Slow)
Type IIa (FFR)
Type II b/x (FF)
16
Q

How are the muscle fibers classified?

A

By the myosin heavy chain(MHC)

17
Q

Within each MU type the fibers can vary, how?

A

In their properties and they co-express different proportions of MHC that can change with training.

18
Q

What are the four main points to distribution?

A

1) fiber type varies within multifunction muscles
2) Fiber type varies between different muscles
3) Variation of same muscle between two different people
4) Vary due to function of muscle

19
Q

What are skeletal muscle contraction types?

A
Isotonic = same tension (lifting weight)
Isokinetic = same velocity (cybex)
Isometric = same measure (no movement)
20
Q

What is a concentric action?

A

Shortening under tension

21
Q

What is an eccentric action?

A

lengthening under tension

22
Q

What is a static action?

A

tension within the muscle but no visible movement

23
Q

How does muscle muscle tension vary?

A

1) Muscle length
2) Joint angle
3) Velocity of movement
4) Percent of fast twitch fibers

24
Q

What is torque?

A

Work and torque are the same

It is a twisting force that tends to cause rotation

25
Q

What effects do muscle length have on tension?

A

Max tension occurs near resting length of the muscle because of max overlap of myosin and actin cross bridge

26
Q

What effects do joint angle have on tension?

A

Muscle tension is greatest some where in the middle of the ROM

27
Q

What effect does velocity of a movement have on tension?

A

Isometric produce the greatest tension
MU Recruitment Times:
-Isometric more time for recruitment
-Fast contraction less time

28
Q

What effect does the percent of fast twitch have on tension?

A

-Higher peak torque at most angular velocities with greater fast twitch fibers

29
Q

What are neural factors influencing muscle tension?

A

1) Conscious CNS drive (Increase/decrease tension)
2) Muscle spindle respond to stretch pf muscle to increase tension
3) Golgi tendon organ and some ligaments respond to tension and cause reflexes

30
Q

What is a muscle spindle?

A

Information about fiber length and tension.

Responds to stretch (counteracts stretch)

31
Q

What is the Golgi tendon organ?

A

Activated by excessive muscle tension

Responds by reflex inhibition of muscle

32
Q

Why does muscle force increase with increase in velocity

A

Greater CNS drive
Greater MU recruitment
Greater passive tension contribution from series and parallel elastic components

33
Q

Muscle power increases with…

A

increase in concentric movement velocity up to 50% max shortening velocity
After ~50% PO decreases

34
Q

Concentric peak torque is inversely related to

A

angular velocity

faster the movement less time for recruitment

35
Q

Muscles with greatest % of FF will have…

A

greatest power/strength output at any given velocity

Larger muscle fibers, faster MN conduction velocity, greater Ca2+ release