9 Muscles and Muscle Tissue
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.
In order to receive a signal to contract, each skeletal muscle must be served by a(n) ________. • artery • nerve • vein • ligament
The functional unit of a muscle fiber is the __________. • sarcomere • myofibril • fascicle • myofilament
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 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.
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
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