A&P Exam 4

1. Which of the following muscle types is both voluntary and striated?

skeletal

1. Each skeletal muscle fiber is controlled by a neuron at a single ___________. a. Neuromuscular junction b. Sarcomere c. Synaptic cleft d. Axon terminal

A

1. The alternating contraction and relaxation of opposing layers of smooth muscle is referred to as ___________. a. Peristalsis b. Treppe c. Isotonic contraction d. Multiunit cell

A

1. The final "go" signal for skeletal muscle contraction is __________. a. an increase in intracellular calcium ion levels b. a decrease in intracellular calcium ion levels c. a decrease in extracellular calcium ion levels d. an increase in extracellular calcium ion levels

A

1. The sequence of electrical changes that occurs along the sarcolemma when a muscle fiber is stimulated is known as the ___________. a. Action potential b. Membrane repolarization c. Membrane hyperpolarization d. Motor end plate potential

A

1. When an action potential arrives at the neuromuscular junction, the most immediate result is __________. a. the release of acetylcholine from the motor neuron b. a rise in intracellular Ca2+ levels in the muscle fiber c. the depolarization of the sarcolemma d. the formation of actin-myosin cross bridges

A

1. Which is not a step in the sliding filament theory? a. Extracellular calcium enters the muscle cell b. Calcium binds to troponin c. Troponin moves tropomyosin d. ATP allows release of cross bridge

A

1. Which of the following does NOT occur during skeletal muscle contraction? a. Calcium binds to myosin heads b. Calcium concentration in the sarcoplasm increases. c. ATP is hydrolyzed. d. The I bands shorten and H zones disappear.

A

1. Which of the following is NOT a characteristic of skeletal muscle contraction? a. It can contract for long periods of time without tiring. b. It contracts rapidly. c. It can exert tremendous power. d. It is voluntary.

A

1. Which of the following muscles is voluntary? a. the muscle that extends the arm at the elbow b. the muscle in the wall of the urinary bladder c. the muscle in the wall of the heart d. the muscle of the stomach

A

1. "Cross bridges" that link between the thick and thin filaments are formed by the ___________. a. tails of myosin filaments b. globular head of thick filaments c. F actin d. globular actin

B

1. A sarcomere is part of a(n) ___________. a. Myofilament b. Myofibril c. Myocyte d. Mitochondria

B

1. Acetylcholinesterase _____________. a. activates acetylcholine b. breaks down acetylcholine c. helps acetylcholine bind to its receptor

B

1. All of the following terms refer to the properties of skeletal muscles, EXCEPT ___________. a. Excitability b. Involuntary c. Contractility d. Conductivity

B

1. In the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and _________. a. Actin b. Myosin c. Tropomyosin d. Thin filaments

B

1. Skeletal muscle cells are electrically insulated from each other by: a. Sarcolemma b. Endomysium c. Perimysium Epimysium

B

1. The functional unit of contraction in a skeletal muscle fiber is the ____________. a. Myofilament b. Sarcomere c. Myofibril d. Sarcolemma

B

1. The most efficient means of producing ATP is _______________. a. Anaerobic respiration b. Aerobic respiration c. Anaerobic glycolysis d. Lactic acid formation

B

1. What would occur if a muscle became totally depleted of ATP? a. The muscle would exhibit isotonic contraction. b. The muscle would remain in a contracted state due to an inability to break actin-myosin cross bridges. c. The muscle would relax and lengthen due to an inability to sustain actin-myosin cross bridges. d. The muscle would exhibit isometric contraction.

B

1. When an action potential arrives at the axon terminal of a motor neuron, what type of ion channel is opened? a. Chemically (ligand) gated calcium channels b. Voltage-gated calcium channels c. Voltage-gated sodium channels d. Chemically (ligand) gated sodium channels

B

1. Where does 95% of the energy needed for contraction come from during moderate exercise? a. Creatine phosphate b. Aerobic respiration c. Anaerobic glycolysis d. Lactic acid

B

1. Which of the following best describes the composition of the structure known as a triad in a skeletal muscle fiber? a. sarcolemma, sarcoplasm, and sarcoplasmic reticulum b. terminal cisterna, transverse tubule, and terminal cistern c. A band, I band, and H band

B

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

B

1. Which of the following substances increases in quantity during repetitive muscle contraction during oxygen deficit? a. adenosine triphosphate (ATP) b. lactic acid c. glucose d. oxygen

B

1. Whole muscle is composed of bundles of muscle cells called: a. Myofibrils b. Fascicles c. Epimysium d. Tendons

B

1. Which of the following is false regarding smooth muscle? a. Smooth muscle is not striated b. Once damaged, smooth muscle is unable to regenerate. c. Smooth muscle tends to be organized in sheets. d. Contraction of smooth muscle is regulated by the autonomic nervous system.

B Not striated because lacks sarcomeres

1. A motor neuron and all the muscle fibers it supplies is called a(n) ____________. a. Neuromuscular junction b. Axon terminal c. Motor unit Motor end plate

C

1. An entire skeletal muscle is surrounded by ___________. a. Endomysium b. Sarcolemma c. Epimysium d. Perimysium

C

1. In order for skeletal muscle cells to contract, they must be stimulated by a/an: a. An adjacent muscle cell via gap junctions b. A sensory neuron c. A motor neuron d. ATP

C

1. The __________ are extensions of the sarcolemma, and serve as a rapid communication system that ensures that every myofibril in the muscle fiber contracts at virtually the same time. a. Think filaments b. Z discs c. T tubules d. A bands

C

1. The binding of a chemical to receptors on the motor endplate opens channels that let which ion enter the cell and cause depolarization? a. Potassium b. Calcium c. Sodium d. ACh

C

1. The part of the sarcoplasmic reticulum where calcium ions are stored is called the: a. Triad b. T tubules c. Terminal cisternae d. Troponin

C

1. The plasma membrane of a muscle cell is called the: a. Sarcolemma b. Sarcoplasmic reticulum c. Sarcoplasm d. Synapse

C

1. The sequence of events that forms the link between electrical activity in the sarcolemma and the initiation of a contraction is called _____________. a. The neuromuscular junction b. The synaptic cleft c. Excitation-contraction coupling d. The sliding filament theory

C

1. The term that means a continued mild or partial contraction of a muscle that keeps it healthy and ready to respond is muscle ___________. a. Summation b. Twitch c. Tone d. Tetanus

C

1. What is the ion released from the terminal cisternae that combines with troponin and removes the blocking action of tropomyosin, resulting in the formation of cross bridges? a. Myosin b. Sodium c. Calcium d. Acetylcholine

C

1. Which of the following is a special adaptation present in skeletal muscle cells, but absent in most other cells? a. Muscle cells have mitochondria; most other cells do not b. Muscle cells have a nucleus; most other cells do not. c. Muscle cells have myoglobin; most other cells do not. d. Muscle cells use ATP to do work; most other cells do not.

C

1. Which one of the following binds calcium ions in a smooth muscle, causing contraction? a. Troponin b. Voltage gate channel c. Calmodulin d. Tropomyosin

C

down by acetylcholinesterase. 1. Myofibrils are composed of repeating contractile elements called __________. a. Actin b. Myofilaments c. Sarcomeres d. Myosin

C

1. The type of fiber most resistant to fatigue are a. Fast twitch muscle b. White muscle c. Type I fibers d. Type II B fibers

C slow twitch

All are functions of skeletal muscle except: a. Controls entrances and exits b. Generates heat c. Controls blood glucose levels d. Constriction and dilation of digestive organs

D

1. Choose the true statement. a. Unlike skeletal muscle, contraction in smooth muscle does not involve a sliding filament mechanism. b. Unlike skeletal muscle, smooth muscle does not depend on ATP to fuel contractions. c. The final signal for contraction in smooth muscle is a rise in extracellular calcium while the final signal for contraction in skeletal muscle is a rise in intracellular calcium. d. Smooth muscle depends on the calcium-calmodulin system to regulate contraction while skeletal muscle relies on the calcium-troponin system to regulate contraction.

D

1. Elasticity refers to the ability of a muscle fiber to ___________. a. Be stretched b. receive and respond to a stimulus c. shorten forcibly when adequately stimulated d. recoil and resume its resting length after being stretched

D

1. The binding of what to the myosin head puts the cross bridge in its high-energy conformation? a. Actin b. Calcium c. Globular head d. ADP (ATP binds to myosin while it is attached to actin, allowing

D

1. The thin myofilaments of skeletal muscle are composed chiefly of __________. a. Myosin b. Tropomyosin c. Troponin d. Actin

D

1. The type of muscle contraction in which the muscle fibers produce increased tension, but the muscle neither shortens nor lengthens, is called _____________. a. Isotonic contraction b. Treppe c. Temporal summation d. Isometric contraction

D

1. Which of the following allows recoil of the muscle fiber when contraction ends? a. Troponin b. Myosin c. Tropomyosin d elastic filaments

D

1. Which of the following statements about smooth muscle is true? a. It has branching fibers. b. Nuclei are peripherally located in the fibers c. Contractions are rapid and forceful. d. Fibers are small and spindle-shaped.

D

1. Which of the following statements is false? a. During contraction, the distance between Z disks of a sarcomere decreases b. During contraction, actin-myosin cross bridges form. c. During contraction, thin filaments slide past thick filaments so that actin and myosin filaments overlap. d. During contraction, thin filaments slide past thick filaments so that actin and myosin filaments do not overlap.

D