9. Muscles and Muscle Tissue. Muscle cells are referred to as ________. muscle fibers muscle spindles muscle myosin muscle actin. Which of the following is not a prefix used to refer to muscle?. Mys Myo Sarco Lemma.
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9 Muscles and Muscle Tissue
Muscle cells are referred to as ________. • muscle fibers • muscle spindles • muscle myosin • muscle actin
Which of the following is not a prefix used to refer to muscle? • Mys • Myo • Sarco • Lemma
Of the following muscle types, which is the only one subject to conscious control? • Smooth • Skeletal • Cardiac • All of these muscle types are subject to conscious control.
Which two types of muscle appear striated when examined under a microscope? • Smooth and skeletal • Smooth and cardiac • Cardiac and skeletal • Skeletal muscle is the only striated muscle type.
Which of the following muscular functions serves a metabolic function? • Movement • Posture maintenance • Joint stabilization • Heat generation
In order to receive a signal to contract, each skeletal muscle must be served by a(n) ________. • artery • nerve • vein • ligament
The elastic components of muscle consist of which elements? • Tendon, epimysium, muscle fiber • Bone, perimysium, blood vessel • Fascicle, bone, blood vessel • Tendon, epimysium, perimysium, endomysium
Which of the following components accounts for the bulk of muscle fiber volume (up to 80%)? • Glycosomes • Mitochondria • Myofibrils • Sarcoplasm
The functional unit of a muscle fiber is the __________. • sarcomere • myofibril • fascicle • myofilament
Which portion of a myosin molecule would be the most severely affected upon exposure to an enzyme inhibitor? • Tail • Hinge region • Head • The actin molecule
The thin filaments are not comprised of which of the following components? • Actin • Titin • Troponin • Tropomyosin
What is the major function of the sarcoplasmic reticulum? • Store sodium ions • Expel sodium ions from the cell • Expel calcium ions from the cell • Store calcium ions
What would happen to intracellular calcium levels if a muscle fiber were treated with a calcium channel–blocking drug? • Intracellular calcium levels would increase. • Intracellular calcium levels would decrease. • Intracellular calcium levels would be unchanged. • The muscle fiber would shrink.
What is the significance of the muscle fiber triad relationship? • The terminal cisternae subdivide the sarcolemma. • The T tubules bring calcium to the sarcoplasmic reticulum. • The sarcoplasmic reticulum transfers calcium to the T tubules. • The T tubules conduct electrical impulses that stimulate calcium release from the sarcoplasmic reticulum.
During a muscle contraction, the sliding filament theory would be apparent in a sarcomere because __________. • the I bands get longer • the A bands get shorter • the H zone becomes less obvious and the Z discs move closer together • the Z discs get pulled closer to the I bands and the H zone becomes more obvious
At the neuromuscular junction, the muscle contraction initiation event is ______. • a release of calcium ions from the sarcoplasmic reticulum • conduction of an electrical impulse down the T tubules • binding of acetylcholine to membrane receptors on the sarcolemma • sliding of actin and myosin filaments past each other
What would be the response of a muscle fiber treated with an acetylcholinesterase inhibitor? • There would be a continued muscle fiber contraction in the absence of additional nervous system stimulation. • The muscle fiber would be nonresponsive to acetylcholine. • Acetylcholine would be retained in the axon ending. • The muscle fiber would contract then relax for a prolonged period of time.
In a muscle fiber, the key intracellular event that stimulates muscle contraction is known as ________. • polarization • depolarization • repolarization • potential
During depolarization, the sarcolemma is most permeable to _______. • sodium ions • potassium ions • calcium ions • chloride ions
The time period between action potential initiation and mechanical activity of a muscle fiber is called the _________. • latent period • refractory period • action potential • excitation period
What is calcium’s function during muscle contraction? • Calcium binds to troponin, changing its shape and removing the blocking action of tropomyosin. • Calcium binds to troponin to prevent myosin from attaching to actin. • Calcium depolarizes the muscle fiber. • Calcium flows down the T tubules to stimulate the influx of sodium from the sarcoplasmic reticulum.
Corpses usually exhibit rigor mortis because __________. • ATP hydrolysis is stimulating myosin head attachment to actin • a lack of ATP hydrolysis prevents myosin head detachment from actin • calcium stores become deficient • sodium stores become deficient
Small precise movements are controlled by ______ motor units. • small • large • many • few
A muscle contraction increases in strength up to a point because ________. • stronger stimuli inhibit motor unit activation • recruitment occurs and more motor units respond to stronger stimuli • more calcium is available in the sarcoplasm • additional neurons begin stimulating each muscle fiber
Isometric contractions come into play when an individual is ________. • jumping • walking uphill • lifting a heavy object • maintaining an upright posture
A sprinter is more likely to depend on _______ respiration to generate ATP, whereas a Tour de France cyclist is more likely to rely on __________ respiration. • anaerobic; aerobic • aerobic; anaerobic • aerobic; aerobic • anaerobic; anaerobic
Sprinters typically possess more ________ muscle fibers. • slow glycolytic • fast glycolytic • slow oxidative • fast oxidative
A major difference between smooth muscle fibers and skeletal muscle fibers in terms of calcium influx is that ______. • smooth muscle fibers have a sarcoplasmic reticulum • calcium ions are stored in the sarcoplasm of smooth muscle • calcium ion influx occurs mostly from the extracellular fluid in smooth muscle • smooth muscle contraction does not involve calcium
A major cellular feature in smooth muscle that contributes to its rhythmicity and ability to participate in peristalsis is the presence of _________. • troponin complex • gap junctions • varicosities • caveolae
The principal neurotransmitter of skeletal muscle is acetylcholine. The major neurotransmitter(s) of smooth muscle is (are) _______. • acetylcholine • epinephrine • norepinephrine • all of the above