Muscle Contractions Flashcards

1
Q

Force of muscle contraction depends on……..

A

The # of formed cross bridges

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2
Q

What are the 4 factors that affect the number of cross bridges

A
  1. Number of muscle fibers stimulated (recruitment) – the more motor units recruited, the greater the force of contraction
  2. Relative size of fibers – the bulkier the muscle, the more tension it can develop
  3. Frequency of stimulation – the higher the frequency, the greater the force of
    contraction
  4. Degree of muscle stretch – muscle fibers at 80-120% of their resting length
    generate more force
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3
Q

Define the length-tension relationship. What does this mean at the level of the myofilaments?

A

length-tension relationship in muscle physiology describes the relationship between the length of a muscle fiber and the force it can generate. It is crucial for understanding muscle function and contraction.

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4
Q

What are the two functional characteristics used to categorize muscle fibers by type?

A
  1. Speed of Contraction (Slow vs Fast Fibers)
    * How fast ATPases split ATP
    * Pattern of electrical activity of motor neurons
  2. Metabolic Pathways Used for ATP Synthesis * Oxidative Fibers use aerobic pathways
    * Glycolytic Fibers use anaerobic glycolysis
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5
Q

Muscles vary in how fast they can contract and for how long they can continue to contract, these are influenced by?

A

Muscle Fiber Type

Load

Recruitment

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6
Q

What are the three muscle fiber types? Which of these types use aerobic pathways for ATP synthesis? Which use anaerobic pathways?

A

skeletal muscle fibers can be classified into 3 types:

◦ Slow Oxidative Fibers

◦ Fast Oxidative Fibers

◦ Fast Glycolytic Fibers

Oxidative = Oxygen
Glycolytic = No oxygen

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7
Q

How is the % that we have of each muscle fiber type determined? Can it be changed? Is the consistent throughout a muscle? Or a motor unit?

A

Determined by genetics

Can be changed with certain types of exercise

  • Most muscles contain a mixture of fiber types – results in a range of contractile speed and resistance to fatigue
  • All the muscle fibers in 1 motor unit are the same type
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8
Q

Think about what types of muscle fibers would be best at completing different activities.

A
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9
Q

A greater load will cause ____________ contraction and __________ duration of contraction.

A

Slower, shorter

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10
Q

Higher recruitment will cause ____________ contraction and __________ duration of contraction.

A

More Motor Units, A faster and more prolonged

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11
Q

List and learn the physiological changes you can expect in response to regular endurance activity.

A
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12
Q

What is disuse atrophy?

A

Degeneration and loss of muscle mass due to the immobilization or loss of neural stimulation

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