Outer connective tissue of skeletal muscles?
Epimysium
Connective tissue surrounding the fasciculi?
Perimysium
Tissue that covers individual muscle fibers?
Endomysium
What does the sarcolemma include?
Plasmalemma & Basement membrane
What does the plasmalemma fuse with?
Tendons
Where do satellite cells reside?
Between the plasmalemma & the basement membrane
The Sarcoplasm involves:
Transverse tubules and sarcoplasmic reticulum
Sarcoplasmic reticulum stores?
Calcium ions (Ca2+)
Thick Filaments are comprised of?
Myosin
Thin filaments are comprised of?
Actin, tropomyosin, and troponin
Excitation
Contraction coupling
Role of calcium in the muscle fiber
Action potentials travel down T-tubules to the cell interior and stimulate the SR to release calcium, which activates the contraction process
Sliding filament theory:
- Ca2+ binds to troponin on actin
- Troponin moves tropomyosin off binding sites
- Myosin head binds to sites
- Myosin head tilts (requires ATP)
- Actin is dragged along
- Myosin breaks away & binds to a new site
- Calcium returns to the SR, contraction stops
What creates the energy for muscle contraction?
ATP binds with myosin
What must happen for muscle relaxation to occur?
The return of calcium to the SR
Type 1 Muscle Fiber
- slow twitch
- high aerobic endurance
- fatigue resistant
Type II Muscle Fiber
- fast twitch
- anaerobic
- generates greater force + power
- fatigue prone
Determinants of fiber type?
Genetics, alpha-motor neuron innervations, long-term training
Muscle fiber recruitment
- activating more motor units = more force
- depends on the force required
- smaller motor units are recruited first (type I before type II)
3 Types of Muscle Contractions
- Concentric
- Static
- Eccentric
Rate Coding
Frequency of stimulation
