Chapter 11: The Musculoskeletal System Flashcards
Which zone or band in the sarcomere does NOT change its length during muscle contraction? Why?
The A-band does not change length during muscle contraction because it is the entire length of the myosin filament. The filaments do not change length, but rather slide over each over; thus, the A-band should remain a constant length during contraction.
What are the events that intiate muscle contraction, in order? Start with neurotransmitter release and trace the pathway to the point where myosin binds with actin.
- Release of acetylcholine from motor neuron
- activation of acetycholine recepors in sarcolema
- depolarization of sarcolema
- spreading of signal using T-tubules
- release of calcium from sarcoplasmic reticulum (SR)
- binding od calcium to troponin
- conformational shift in tropomyosin
- exposure of myosin-binding sites
- myosin binds to actin
What roles does the binding of ATP to myosin head play in the cross-bridge cycle? What about the dissociation of ADP and inorganic phosphate from the myosin head?
- Binding of ATP
- Dissociation of ADP and inorganic phosphate
- Binding of ATP
- ATP binding allows the myosin filament to disconnect from actin.
- Dissociation of ADP and inorganic phosphate
- Causes th power stroke
What is tetanus (the physiological phenomenon, not the disease)
Tetanus os the summation of multiple simple twitches that occur to quickly for the muscle to relax. This leads to a stronger and more prolonged contraction of the muscle.
What are the three types of muscles?
- Skeletal
- Smooth
- Cardiac
____ is responsible for voluntary movement and is therefore innervated by the somatic nervous system?
Skeletal Muscle
What are the types of fibers in skeletal muscles?
Slow-twitch fibers (Red fibers)
Fast-twitch fibers (White fibers)
Slow twitch fibers
Have high myoglbin content and primarily derive their energy aerobically. Also contain many mitochondria to execute oxidative phosphorylation.
Muscles that contract slowly, but that can sustain activity (such as the muscles that support posture).
Myoglobin
Ocygen carrier that uses iron in a heme group to bind oxygen, imparting a red color.
Fast-twitch fibers
contain much less myoglobin. Thats why they appear white.
Muscles that contract rapidly, but fatigue quickly.
____ muscle that is responsible for involuntary action?
Smooth
What is special about smooth and cardiac muscles?
Myogenic Activity
They can contract without nervous system input.
____ muscle has charectristics of both smooth and skeletal muscle?
Cardiac
Cardiac muscle cells are conneted by ____, which contain many ____.
Intercalated discs
Gap Junctions