The different types of muscle tissue differ from each other by
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microscopic anatomy.
location.
type of Control.
both microscopic anatomy and location.
all of these choices are correct.
all of these choices are correct.
In the drawing, the circle is indicating a:
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filament.
myofibril.
muscle fiber.
myofibril fascicle.
somatic motor neuron.
muscle fiber.
Which of the following is directly responsible for transmitting an action potential from a motor neuron to a skeletal muscle fiber?
intercalated discs
gap junctions
myofibrils
creatine phosphate
acetylcholine
acetylcholine
Which of the following correctly lists the sequence of structures that action potentials must move through to excite skeletal muscle contraction?
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axon of neuron, sarcolemma, T tubules
myofibrils, myofilaments, mitochondria
sarcolemma, axon of neuron, T tubules
T tubules, sarcolemma, myofilament
muscle fiber, axon of neuron, myofibrils
axon of neuron, sarcolemma, T tubules
Skeletal muscle contraction will continue to occur as long as the following chemicals are available in the cytosol of the muscle fiber.
ATP and acetylcholine (ACh)
ACh and potassium ions
Sodium ions and ATP
Calcium and ACh
Calcium ions and ATP
calcium ions and ATP
Calcium binds to the troponin-tropomyosin complex and allows myosin to access the actin filaments.
True
False
True
Choose the correct sequence of events:
Action potential reaches synapse—Acetylcholine is released by motor neuron— Calcium ions enter motor neuron— Sodium ions flood into the muscle cell— Acetylcholine binds to gated ion channels on sarcolemma, transferring the action potential.
Action potential reaches synapse—Calcium ions enter motor neuron—Acetylcholine is released by motor neuron—Acetylcholine binds to gated ion channels on sarcolemma—Sodium ions flood into the muscle cell, transferring the action potential.
Action potential reaches synapse— Acetylcholine is released by motor neuron—Acetylcholine binds to gated ion channels on sarcolemma—Calcium ions enter motor neuron—Sodium ions flood into the muscle cell, transferring the action potential.
None of these.
Action potential reaches synapse—Calcium ions enter motor neuron—Acetylcholine is released by motor neuron—Acetylcholine binds to gated ion channels on sarcolemma—Sodium ions flood into the muscle cell, transferring the action potential.
A group of muscle cells stimulated by a single motor neuron is known as a
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neuron divergence.
motor unit.
myofibril.
contractile structure.
motor unit.
Frequency of stimulation of a muscle cell is not a factor that influences tension.
True
False
False
Alternate contractions allow for sustained contraction in a whole muscle.
True
False
True
This structure is unique to cardiac muscle cells, and allows individual cells to be firmly attached to each other (to provide mechanical strength during contraction), and also allow the action potential to spread rapidly through the cardiac muscle tissue, so that contractions are smooth and coordinated.
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sarcomeres
desmosomes
gap junctions
intercalated discs
Z discs
intercalated discs
Smooth muscle fibers do not have striations like skeletal and cardiac
muscle cells do. This is because:
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the sarcomeres are smaller than in cardiac muscle cells and skeletal fibers, and aren't visible even when smooth muscle fibers are examined microscopically
smooth muscle fibers contain only intermediate filaments, which aren't arranged in sarcomeres
smooth muscle fibers contain thin and thick filaments, as well as intermediate filaments, but none of them are arranged in sarcomeres
visceral smooth muscle fibers don't have striations, but multiunit smooth muscle cells do, but these cells are more rare, and so we rarely have a chance to view them with a microscope
smooth muscle fibers contain only intermediate filaments, which aren't arranged in sarcomeres and visceral smooth muscle fibers don't have striations, but multiunit smooth muscle cells do, but these cells are more rare, and so we rarely have a chance to view them with a microscope
smooth muscle fibers contain thin and thick filaments, as well as intermediate filaments, but none of them are arranged in sarcomeres
Which of the following types of muscle tissue contract when excited by their own autorhythmic muscle fibers?
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cardiac muscle
slow twitch oxidative skeletal muscle
multi-unit smooth muscle
fast twitch glycolytic skeletal muscle
all of these choices are correct
cardiac muscle
Smooth muscle tone is maintained by the prolonged presence of _____ in the muscle cell’s cytosol?
ATP
Calcium ions
Phosphate ions
Myoglobin
None of these choices
Calcium ions