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• There
are three types of skeleton: hydrostatic skeletons, exoskeletons, and
endoskeletons.
• Bone is formed by the secretion of an organic matrix
by osteoblasts; this organic matrix becomes calcified.
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1. What are
the two major components of the extracellular matrix in bone? What structural
properties does each component have? How do the two components combine
to make bone resistant to fracture?
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• Freely
movable joints surround the articulating bones with a synovial capsule
filled with a lubricating fluid.
• Skeletal muscles can work together as synergists,
or oppose each other as antagonists.
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2. What are
the three types of joints in a vertebrate skeleton? Give an example of
where each type is found in the body.
3. What is the difference between a skeletal muscle's origin and
its insertion?
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• A
muscle fiber contains numerous myofibrils that are composed of myofilaments
of myosin and actin.
• There are small cross-bridges of myosin that extend
out toward the actin; the cross-bridges are activated by the hydrolysis
of ATP so that it can bind to actin and undergo a power stroke that causes
the sliding of the myofilaments.
• When Ca++ binds to troponin, the tropomyosin shifts
position in the thin filament, allowing the cross-bridges to bind to actin
and undergo a power stroke.
• The release of Ca++ from the sarcoplasmic reticulum
is stimulated by impulses in the muscle fiber produced by neural stimulation.
• Slow-twitch fibers are adapted for aerobic respiration
and are resistant to fatigue; fast-twitch fibers can provide power quickly
but produce lactic acid and fatigue quickly.
• Cardiac muscle cells have gap junctions that permit
the spread of electric impulses from one cell to the next.
• Cardiac and smooth muscles are involuntary; the contractions
are automatically produced in cardiac muscle and some smooth muscles.
• Animals have adapted modes of locomotion to three
different environments: water, land, and air.
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4. Of what
proteins are thick and thin filaments composed?
5. Describe the steps involved in the cross-bridge cycle. What
functions does ATP perform in the cycle?
6. Describe the steps involved in excitation-contraction coupling.
What functions do acetylcholine and Ca++ perform in this process?
7. How does a somatic motor neuron stimulate a muscle fiber to
contract?
8. What is the difference between a muscle twitch and tetanus?
9. Why can't a myocardium produce a sustained contraction?
10. How does smooth muscle differ from skeletal muscle in terms
of thick and thin filament organization, the role of Ca++ in contraction,
and the effect of stretching on the muscle's ability to contract?
11. What do all modes of locomotion have in common?
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