A&P chapter 9

The cross bridge cycle starts when _________. ATP binds to troponin and is hydrolyzed to ADP and Pi Ca2+ from the sarcoplasmic reticulum binds to troponin Ca2+ is actively transported into the sarcoplasmic reticulum Ca2+ from the sarcoplasmic reticulum binds to tropomyosin acetylcholine diffuses away from the synaptic cleft

Ca2+ from the sarcoplasmic reticulum binds to troponin

What level of structural organization does the actin and myosin in a sarcomere of a muscle fiber represent? Molecular Organ Cellular Tissue

Molecular

Inadequate calcium in the neuromuscular junction would directly affect which of the following processes? Release of acetylcholine from the synaptic vesicles Depolarization of the junctional folds Conduction of action potentials by the motor neuron Breakdown of acetylcholine by acetylcholinesterase

Release of acetylcholine from the synaptic vesicles

Slow oxidative muscle fibers are best suited for __________. hitting a baseball running a marathon lifting heavy weights at the gym running a 100-yard dash

Running a Marathon

Which of the following are correctly paired? cardiac muscle; voluntary control cardiac muscle; nonstriated skeletal muscle; voluntary control smooth muscle; striated

Skeletal Muscle; Voluntary control

One action potential in a motor neuron causes the full reaction in skeletal muscle, which is called a twitch. One twitch can generate max tension in a muscle. Are these statements true or false? Both of these statements are false. Both statements are true. The first statement is true; the second statement is false. The first statement is false; the second statement is true.

The first statement is true; the second statement is false.

The most efficient means of producing ATP is __________. aerobic respiration anaerobic glycolysis lactic acid formation anaerobic respiration

aerobic respiration

Which of the following is the correct sequence of events for muscle contractions? muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

The alternating contraction and relaxation of opposing layers of smooth muscle is referred to as ___________. automatic contraction isotonic contraction peristalsis isometric contraction

peristalsis

The __________ shorten(s) during muscle contraction Actin Z lines sarcomere thick filament

sarcomere

Reduction in blood flow to a muscle fiber would have the greatest effect on ________. both slow and fast oxidative fast oxidative fibers fast glycolytic slow oxidative fibers

slow oxidative fibers

Unlike skeletal muscle, smooth muscle may spontaneously contract when it is stretched. What feature of smooth muscle allows it to stretch without immediately resulting in a strong contraction? low energy requirements slow, prolonged contractile activity smooth muscle tone stress-relaxation response

stress-relaxation response

If a muscle is applied to a load that exceeds the muscle's maximum tension, __________. the contraction is isotonic the muscle length will not change during contraction the muscle length will shorten during contraction the load will be moved by the contraction

the muscle length will not change during contraction

Although all the anatomical parts of muscle work together to give it it's characteristics, which of the following proteins listed below would be most associated with the characteristics of contractility? thick (myosin) filaments voltage gated sodium channels potassium (K+) leak channels elastic (titin) filaments

thick (myosin) filaments

Which type of muscle is found in the body wall of hollow organs? multi unit smooth muscle skeletal muscle unitary smooth muscle cardiac muscle

unitary smooth muscle

Botulism and myasthenia gravis are conditions that cause muscle weakness. Which of these statements is NOT true? In myasthenia gravis, acetylcholine is released, but the receptors on the junctional folds of the sarcolemma cannot receive the acetylcholine. Both conditions are caused by an inability of the body to produce adequate acetylcholine. Botulinum toxin impairs the release of acetylcholine from the presynaptic neuron. Both conditions affect normal activity at the neuromuscular junction.

Both conditions are caused by an inability of the body to produce adequate acetylcholine.

Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction? Sodium release from the sarcoplasmic reticulum initiates the contraction. Calcium release from the sarcoplasmic reticulum initiates the contraction. Action potentials propagate into the interior of the skeletal muscle fiber. Voltage-sensitive proteins change shape.

Calcium release from the sarcoplasmic reticulum initiates the contraction.

Which one of the following binds calcium ions in a smooth muscle, causing contraction? tropomyosin actin calmodulin myosin troponin

Calmodulin

All of the following terms refer to the ability to receive and respond to a stimulus, EXCEPT ___________. irritability responsiveness contractility excitability

Contractility

Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process? Excitation refers to the shape change that occurs in voltage-sensitive proteins in the sarcolemma. Excitation, in this case, refers to the propagation of action potentials along the sarcolemma. Excitation refers to the propagation of action potentials along the axon of a motor neuron. Excitation refers to the release of calcium ions from the sarcoplasmic reticulum.

Excitation, in this case, refers to the propagation of action potentials along the sarcolemma.

ATP is required to cause the power stroke in the myosin head. True False

False

The longer a muscle is when it starts contracting, the more tension it can generate in the contraction. True False

False

Which of the following substances increases in quantity during repetitive muscle contraction during oxygen deficit? glucose oxygen adenosine triphosphate (ATP) creatine phosphate lactic acid

Lactic Acid

Which of the following is a factor that affects the velocity and duration of muscle contraction? size of the muscle fibers stimulated muscle length load on the fiber number of muscle fibers stimulated

Load on the Fiber

A myosin molecule in the thick filaments can be considered a protein having a quaternary structural level. Which of the following best describes this structural level? Myosin has an ATP binding site, actin binding site and flexible hinge region. Myosin is involved in the power stroke of muscle contraction. Myosin molecules consist of two heavy and two light polypeptide chains. Myosin is a primary component within a myofibril.

Myosin molecules consist of two heavy and two light polypeptide chains.

Duchenne muscular dystrophy could theoretically be cured if a technique was developed that would _________. strengthen the dystrophin proteins that are present in the patient's muscle fibers double the existing number of dystrophin molecules in the patient's muscle fibers strengthen the thick and thin filaments in the patient's muscle fibers none of the above

None of the above

What structure most directly stimulates a skeletal muscle fiber to contract? Acetylcholinesterase Motor neuron Voltage-gated calcium channels Synaptic cleft

Notor Neuron

Which of the following statements is true? Cardiac muscle cells have many nuclei. Skeletal muscle cells are long and cylindrical with many nuclei. Cardiac muscle cells are found in the heart and large blood vessels. Smooth muscle cells have T tubules.

Skeletal muscle cells are long and cylindrical with many nuclei

Which of the following statements is FALSE? Skeletal muscle cells are multinucleated. Skeletal muscle cells have T tubules. Skeletal muscle cells contain myoglobin. Skeletal muscle cells use creatine phosphate instead of ATP to do work. Skeletal muscle cells have glycosomes.

Skeletal muscle cells use creatine phosphate instead of ATP to do work.

Which of the following statements is INCORRECT? Skeletal muscles form valves regulating the passage of substances through internal openings of the digestive and urinary tracts. Skeletal muscles support the weight of some internal organs. Skeletal muscles are responsible for the pumping action of the heart. The contractions of skeletal muscles pull on tendons and move elements of the skeleton. Skeletal muscle contractions help maintain body temperature.

Skeletal muscles are responsible for the pumping action of the heart.

If troponin is a component of both cardiac and skeletal muscle, why is an elevated plasma troponin level useful in diagnosing myocardial damage? The subunits of the troponin in cardiac muscle are unique to heart muscle. Patients who have experienced acute cardiac damage often injure their skeletal muscles as they fall to the ground, releasing troponin. Troponin is an important component of all striated muscle, so an increase level of its subunits is a nonspecific indicator of damage to either type of muscle. Whenever cardiac muscle is damaged, skeletal muscles receive inadequate blood flow and release troponin.

The subunits of the troponin in cardiac muscle are unique to heart muscle.

The interaction between which protein and ion initiates muscle coupling? tropomyosin; calcium ions troponin; sodium ions myosin; sodium ions troponin; calcium ions

Troponin; calcium ions

Isometric contractions are important contractions that allow humans to hold their posture over time. True False

True

Although all the anatomical parts of muscle work together to give it its characteristics, which of the following proteins listed below would be most associated with the characteristics of extensibility? potassium (K+) leak channels elastic (titin) filaments acetylcholine receptors in the motor end plate thick (myosin) filaments

elastic (titin) filaments

Addition of more mitochondria to a muscle fiber will have the least effect on ________. fast oxidative fibers fast glycolytic fibers slow oxidative fibers both slow and fast oxidative fibers

fast glycolytic fibers

Properly controlled skeletal muscle contractions produced by changing the frequency of stimulation or the strength of stimulation are accomplished by __________. muscle twitch wave summation multiple motor unit summation graded muscle response

graded muscle response