Skeletal Muscles Flashcards
Bands of tough, fibrous connective tissue that connects muscle to bone (distal and proximal end)
Tendon
Small bundles of muscle fibers
Fasciculus
Long, multinucleated cell that generates force when stimulated
Muscle Fiber
Portion of muscle composed of thin and thick myofilaments (actin and myosin)
Myofibril
Contractile proteins in muscle = ?
Contractile Proteins in Muscle:
- 1) Actin
- 2) Myosin
What is the role of connective tissue?
- Stabilizes and supports components of skeletal muscle
- Surrounds muscle at each organizational level
What are the 3 layers of connective tissue in muscle?
- Epimysium: covers whole muscle
- Perimysium: covers bundles of muscle fibers (fasciculi)
- Endomysium: covers individual muscle fibers
What phase of movement requires overcoming gravity and/or load = ?
What phase of movement requires overcoming gravity and/or load = Concentric phase
- Concentric phase = Muscle contracts/shortens
What phase of movement requires resisting gravity and/or load = ?
What phase of movement requires resisting gravity and/or load = Eccentric phase
Eccentric phase = Muscle lengthens/elongates; stores energy
Components of a Sarcomere…
- Z-line = ?
- H-zone = ?
- I-band = ?
- A-Band = ?
- M-Line = ?
Components of a Sarcomere:
- Z line: At each end of sarcomere
- H zone: In middle of sarcomere, contains myosin
- I bands: At edges of sarcomere, contain actin
- A band: Overlapping acting and myosin
- M line: Middle of H zone, holds myosin in place
Characteristics of Type 1 fibers include = ?
Type 1 Fibers (slow twitch):
- Slow to reach peak force production
- Low peak force production
- High capacity for oxidative metabolism (lots of mitochondria, higher capillary density, high ATP production)
- Fatigue-resistant
- Endurance performance
Explain about Type 2 (fast twitch) fibers
- Rapidly develop force
- High peak force
- Low capacity for oxidative metabolism
- Fatigue easily
- Sprint, short term performance
(Anaerobic glycolysis, stores more ATP-PC in muscle)
Steps mediating the contraction process
Steps Mediating Muscle Contraction Process:
- Electrical impulse generated at neuromuscular junction
- Impulse spreads across sarcolemma into T-tubules
- Receptors release Ca++ into muscle fibers
- Ca++ binds to troponin
- Tropomyosin uncovers active sites of actin
- Myosin crossbridges heads bind actin, form actomyosin complex
- Heads pull actin toward center of sarcomere (power stroke)
- Force is produced
What is muscle strength?
The amount of force generated by a group of muscles in one contraction
What is muscular endurance?
The ability of a muscle group to contract repeatedly without fatigue