Muscle Contractions Flashcards
Force of muscle contraction depends on……..
The # of formed cross bridges
What are the 4 factors that affect the number of cross bridges
- Number of muscle fibers stimulated (recruitment) – the more motor units recruited, the greater the force of contraction
- Relative size of fibers – the bulkier the muscle, the more tension it can develop
- Frequency of stimulation – the higher the frequency, the greater the force of
contraction - Degree of muscle stretch – muscle fibers at 80-120% of their resting length
generate more force
Define the length-tension relationship. What does this mean at the level of the myofilaments?
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.
What are the two functional characteristics used to categorize muscle fibers by type?
- Speed of Contraction (Slow vs Fast Fibers)
* How fast ATPases split ATP
* Pattern of electrical activity of motor neurons - Metabolic Pathways Used for ATP Synthesis * Oxidative Fibers use aerobic pathways
* Glycolytic Fibers use anaerobic glycolysis
Muscles vary in how fast they can contract and for how long they can continue to contract, these are influenced by?
Muscle Fiber Type
Load
Recruitment
What are the three muscle fiber types? Which of these types use aerobic pathways for ATP synthesis? Which use anaerobic pathways?
skeletal muscle fibers can be classified into 3 types:
◦ Slow Oxidative Fibers
◦ Fast Oxidative Fibers
◦ Fast Glycolytic Fibers
Oxidative = Oxygen
Glycolytic = No oxygen
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?
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
Think about what types of muscle fibers would be best at completing different activities.
A greater load will cause ____________ contraction and __________ duration of contraction.
Slower, shorter
Higher recruitment will cause ____________ contraction and __________ duration of contraction.
More Motor Units, A faster and more prolonged
List and learn the physiological changes you can expect in response to regular endurance activity.
What is disuse atrophy?
Degeneration and loss of muscle mass due to the immobilization or loss of neural stimulation