Ch. 7 A and P Questions

The stiffness that occurs at death, when actin and myosin molecules stay linked to each other in a contracted state, is due to a lack of A) cAMP. B) DNA. C) RNA. D) ATP. E) tRNA.

ATP

Which of the following is one of the steps that ends a contraction? A) Sarcoplasmic reticulum absorbs sodium ions. B) Acetylcholine binds to receptors on the sarcolemma. C) Calcium ions bind to troponin. D) Acetylcholine is broken down by acetylcholinesterase. E) An action potential spreads across the entire surface of the muscle fiber.

Acetylcholine is broken down by acetylcholinesterase.

Which of the following statements describes the cause for the cessation of an action potential? [Learning Outcome: 7-4, Level 1]

Acetylcholinesterase breaks down acetylcholine.

Which of the following occurs when glycolysis produces pyruvate faster than it can be used by the mitochondria? A) Pyruvate levels drop in the cytoplasm. B) Lactic acid is produced. C) Pyruvate is converted to sucrose. D) Lactic acid dissociates into a water molecule and hydrogen. E) Oxygen is produced.

Lactic acid is produced.

Which of the following statements concerning the recovery period of muscle activity is true? [Learning Outcome: 7-6, Level 2]

Lactic acid removal occurs

Why do individual muscle twitches have to be added together, as in summation or tetanus? A) Only added twitches produce any muscle contraction: A fiber undergoing a muscle twitch does not contract at all. B) There has to be a critical mass of muscle twitches for calcium to be released into the muscle cell. C) Not enough acetylcholine will be produced for contraction without multiple twitches. D) Multiple twitches add up to an increase in muscle fiber tension, which increases the strength of the muscle. E) Not enough ATP is generated by one muscle twitch.

Multiple twitches add up to an increase in muscle fiber tension, which increases the strength of the muscle.

A resting muscle generates most of its ATP by A) conversion of creatine phosphate. B) anaerobic respiration. C) aerobic respiration. D) glycolysis. E) heat loss.

aerobic respiration.

Smooth muscle cells A) have to be innervated by motor neurons. B) are larger than cardiac muscle cells. C) are multinucleate. D) contain intercalated discs. E) are spindle-shaped.

are spindle-shaped

The ________ contains vesicles filled with acetylcholine. A) axon terminal B) motor end plate C) neuromuscular junction D) synaptic cleft E) transverse tubule

axon terminal

The enzyme acetylcholinesterase causes acetylcholine to A) break down. B) synthesize. C) bond to actin. D) be secreted. E) form cross-bridges.

break down

The active sites on actin molecules are usually covered up by other molecules. What is the critical material required to uncover the active sites on the actin molecules that will then bind to myosin heads? A) ATP B) calcium C) oxygen D) vitamin A E) titin

calcium

In response to action potentials arriving from the transverse tubules, the sarcoplasmic reticulum releases A) acetylcholine. B) sodium ions. C) potassium ions. D) calcium ions. E) acetylcholinesterase.

calcium ions.

Regarding muscle fiber elongation, A) many active mechanisms exist for muscle fiber elongation. B) muscle contraction is passive; whereas, elongation is active. C) opposing muscle movements are not a factor. D) gravity may help lengthen a muscle fiber after elongation. E) elastic forces are generated where a muscle fiber elongates.

gravity may help lengthen a muscle fiber after elongation.

Which of the following occurs when tension production rises to a peak and very brief periods of relaxation occur? A) resting period B) latency C) tension plateau D) incomplete tetanus E) complete tetanus

incomplete tetanus

Glycolysis A) is an anaerobic process. B) is the breakdown of pyruvate to glucose. C) acts as the only source of ATP in muscle tissue. D) is only active during rest. E) occurs in the nucleus.

is an anaerobic process.

"Anaerobic endurance" A) is used during long, slow athletic activities. B) is exemplified by contractions of fast muscle fibers. C) is determined by the availability of carbohydrates, lipids, or amino acids for breakdown. D) is the length of time a muscle can continue to contract while supported by mitochondrial activities. E) does not promote muscle hypertrophy.

is exemplified by contractions of fast muscle fibers.

Calcium ions are released from the sarcoplasmic reticulum during the ________ phase of contraction. A) latent B) contraction C) twitch D) relaxation E) recovery

latent

Regarding lactic acid regulation, which cells in the body consume extra oxygen and produce ATP for the conversion of excess lactate absorbed from the blood back to glucose? A) neurons B) cardiac muscle cells C) skeletal muscle fibers D) liver cells E) erythrocytes

liver cells

A sheath of connective tissue surrounding a bundle of striated muscle fibers is called A) endomysium. B) perimysium. C) sarcolemma. D) epimysium. E) sarcoplasmic reticulum.

perimysium

Which of the following functions is NOT characteristic of skeletal muscle? [Learning Outcome: 7-1, Level 1]

producing blood cells

Lactic acid is recycled by converting it to which of the following compounds? [Learning Outcome: 7-6, Level 1]

pyruvate

Creatine phosphate serves to A) cause the decomposition of ATP. B) supply energy to synthesize ATP. C) decompose ADP. D) synthesize ADP. E) synthesize glucose.

supply energy to synthesize ATP

Acetylcholinesterase is found within the A) nucleus. B) sarcolemma. C) myofibril. D) sarcomere. E) synaptic cleft.

synpatic cleft

The amount of tension produced by an individual muscle fiber depends solely upon which of the following factors? [Learning Outcome: 7-5, Level 1]

the number of pivoting cross-bridges

What is the function of the transverse tubule? A) the storage of calcium ions B) to transmit electrical impulses to the cell's interior C) to store sodium ions D) to allow cross-bridge attachment E) to produce myofibrils

to transmit electrical impulses

During the start of a skeletal muscle contraction, calcium binds to which molecule? [Learning Outcome: 7-3, Level 2]

troponin

Tropomyosin strands are held in position by which of the following? A) actin molecules B) myosin molecules C) troponin molecules D) ATP molecules E) calcium ions

troponin molecules

A person whose genetic makeup makes him or her a better marathon runner than a sprinter probably has more ________ in his or her leg muscles. A) fast fibers B) intermediate fibers C) slow fibers D) dark fibers E) red fibers

slow fibers

Nonstriated, involuntary muscle is A) cardiac. B) red skeletal. C) smooth. D) white skeletal. E) intermediate skeletal.

smooth

As a skeletal muscle contraction is initiated, acetylcholine binding alters the motor end plate membrane's permeability to A) acetylcholinesterase. B) sodium ions. C) calcium ions. D) chloride ions. E) potassium ions.

sodium ions

The heart has to be able to regulate its contractions. Heart muscle, unlike skeletal muscle, cannot go into a tetanus. This is because A) the heart muscle has to be able to consistently contract and pump blood in a controlled fashion. B) heart muscle is not resistant to fatigue. C) heart muscle contracts faster than skeletal muscle. D) heart muscle cannot use glycogen. E) the heart uses aerobic metabolism.

the heart muscle has to be able to consistently contract and pump blood in a controlled fashion.

Regarding a skeletal muscle fiber, wherever a T-tubule encircles a myofibril, the tubule is tightly bound to A) the nucleus. B) the sarcolemma. C) the endomysium. D) the sarcoplasmic reticulum. E) thick filaments.

the sarcoplasmic reticulum

A single stimulus-contraction-relaxation sequence in a muscle fiber is known as a(n) A) incomplete tetanus. B) latent period. C) complete tetanus. D) summation. E) twitch.

twitch

Smooth muscle A) does not use calcium. B) is not resistant to fatigue. C) contracts faster than skeletal muscle. D) does not undergo tetanus. E) uses primarily aerobic metabolism.

uses primarily aerobic metabolism

Each myofibril consists of approximately ________ sarcomeres. A) 10 B) 500 C) 10,000 D) 100,000 E) 2-3 million

10,000

In the contraction phase of a single muscle twitch, maximum tension is reached approximately how long after stimulation? [Learning Outcome: 7-5, Level 1]

15 milliseconds

Place these steps of muscle contraction in the correct order. 1. Action potential is generated along the sarcolemma 2. Nerve impulse arrives at synapse 3. Calcium is released into muscle cell cytoplasm 4. Acetylcholine is produced 5. Actin and myosin molecules continuously cross-link, with actin molecules being pulled inward

2, 4, 1, 3, 5 -Nerve impulse arrives at synapse -Acetylcholine is produced -Action potential is generated along the sarcolemma -Calcium is released into muscle cell cytoplasm -Actin and myosin molecules continuously cross-link, with actin molecules being pulled inward

The region of a sarcomere containing myosin, going from one end of the myosin molecules to the other end of the myosin molecules, is the A) Z line. B) M line. C) H band. D) A band. E) I band.

A band

Which of the following is characteristic of cardiac muscle? A) Cardiac muscle cells are striated. B) Cardiac muscle cells achieve tetany with every contraction. C) Cardiac muscle fibers are multinucleated. D) Cardiac muscle fibers are faster than skeletal muscles. E) Neurons that innervate cardiac muscle tissue are under voluntary control.

Cardiac muscle cells are striated.

Which of the following statements regarding smooth muscle is true? [Learning Outcome: 7-8, Level 1]

Contraction occurs over a greater range of lengths than occurs in cardiac muscle or skeletal muscle.

During moderate activity, which of the following is true regarding muscle metabolism? A) The ATP produced is used to build energy reserves of ATP and glycogen. B) Most ATP is produced through glycolysis, with lactate and hydrogen ions as byproducts. C) Glucose and fatty acids are catabolized. D) Mitochondrial activity provides about one-third of the ATP consumed. E) Mitochondria are not involved.

Glucose and fatty acids are catabolized.

The area of the sarcomere that is the light region between two successive A-bands is the A) Z line. B) M line. C) I band. D) myofibril. E) H band.

I band

Which of the following is true about red muscles? A) Red muscles are slower than white muscles. B) Red muscles have fewer mitochondria than white muscles. C) Red muscles have fibers of greater diameter than those of white muscles. D) Red muscles contain less myoglobin than white muscles. E) Red muscles fatigue quickly.

Red muscles are slower than white muscles.

Which of the following is an accurate characteristic of slow fibers? A) Slow muscle tissue has a much less extensive network of capillaries than does typical fast muscle tissue. B) Resting slow muscle fibers contain oxygen reserves, bound to myoglobin. C) Slow muscle tissue has a lower oxygen supply than does fast muscle tissue. D) Slow muscle fibers contain fewer mitochondria than do fast muscle fibers. E) Slow muscle fibers contain myoglobin, a globular protein, which binds sodium.

Resting slow muscle fibers contain oxygen reserves, bound to myoglobin.

Which of the following statements describes how muscles help maintain homeostasis? A) The contractions of skeletal muscles pull on tendons and move elements of the skeleton. B) Skeletal muscles are responsible for guarding the openings of the digestive and urinary tracts. C) Skeletal muscles are responsible for the pumping action of the heart. D) Skeletal muscles support the weight of some internal organs. E) Skeletal muscle contractions help maintain body temperature.

Skeletal muscle contractions help maintain body temperature.

Which statement regarding skeletal muscle is true? A) Skeletal muscles are directly, but not indirectly, attached to bones. B) Skeletal muscles do not contain connective tissue. C) Skeletal muscles do not maintain body temperature. D) Skeletal muscles do not contain nervous tissue. E) Skeletal muscles contain blood vessels.

Skeletal muscles contain blood vessels.

Myofibrils are made primarily of A) actin and myosin. B) epimysium. C) ATP and ADP. D) troponin. E) tropomyosin.

actin and myosin

Which statement regarding isometric contractions is true? A) Tension rises during a contraction. B) The skeletal muscle's length changes. C) The tension produced never exceeds the load. D) Tension remains at a constant level until relaxation occurs. E) Examples are walking and running.

The tension produced never exceeds the load.

Which of the following statements regarding fast fibers is true? [Learning Outcome: 7-7, Level 1]

Their power comes from the anaerobic process of glycolysis.

A triad is __________. [Learning Outcome: 7-3, Level 1]

a pair of terminal cisternae of the SR with a T tubule between them

Upon the nerve impulse arriving at the axon terminal, A) active sites on actin are exposed. B) active sites on myosin are exposed. C) actin heads will bind to myosin. D) muscle relaxation occurs. E) acetylcholine is released.

acetylcholine is released.

Muscle cells A) actively lengthen. B) generate compression. C) possess a mechanism that regulates the tension amount by changing the number of contracting sarcomeres. D) vary tension production based on the amount of sodium ions bound to actin. E) can only contract.

can only contract

During which phase is the stimulus frequency so high that the relaxation phase is eliminated? A) complete tetanus B) a twitch C) incomplete tetanus D) recovery E) recruitment

complete tetanus

The structure that ties adjacent muscle fibers together is the __________. [Learning Outcome: 7-2, Level 1]

endomysium

A layer of collagen fibers that surrounds an entire muscle is called A) endomysium. B) perimysium. C) sarcolemma. D) sarcomere. E) epimysium.

epimysium

A muscle ________ contains a sarcolemma, sarcoplasm, myofilaments, and myofibrils. A) fiber B) intercalated disc C) T-tubule D) myofibril E) motor end plate

fiber

During activities requiring aerobic endurance, A) glycogen and glycolysis are the primary sources of reserve energy. B) amino acids are not broken down. C) most of the muscle's energy is produced in mitochondria. D) fatigue occurs in a few minutes. E) muscle hypertrophy often occurs.

most of the muscle's energy is produced in mitochondria.

The specialized sarcolemma that contains acetylcholine receptors is the A) synaptic knob. B) motor end plate. C) motor unit. D) synaptic cleft. E) I band.

motor end plate

Neurotransmitters that cause skeletal muscle contraction are normally stored in A) myofibrils. B) motor neuron axon terminals. C) motor units. D) motor end plates. E) actin.

motor neuron axon terminals

Exhaustion of energy reserves or decline in pH due to production and dissociation of lactic acid causes A) muscle contraction. B) the conduction of neural information to the muscle fiber. C) muscle relaxation. D) muscle fatigue. E) the striated appearance of skeletal muscle.

muscle fatigue.

Botulism A) is the result of an attack on acetylcholine receptors by the immune system. B) is usually tied to a genetic predisposition. C) is a viral illness. D) results from the loss of acetylcholine receptors at the motor end plate. E) results from a bacterial toxin that prevents the release of acetylcholine at the axon terminals.

results from a bacterial toxin that prevents the release of acetylcholine at the axon terminals.

The area between Z lines is the A) sarcolemma. B) sarcomere. C) sarcoplasmic reticulum. D) myofibril. E) myofilament.

sarcomere

The terminal cisternae are structural features of the A) myofilaments. B) sarcoplasmic reticula. C) myofibrils. D) I bands. E) sarcolemma.

sarcoplasmic reticula

The skeletal muscles store calcium ions in the terminal cisternae of the A) sarcolemma. B) sarcomere. C) sarcosome. D) sarcoplasmic reticulum. E) sarcoplasm.

sarcoplasmic reticulum

Smooth muscle forms __________. [Learning Outcome: 7-8, Level 1]

sheets, bundles, sheaths around other tissues

The thick filaments of sarcomeres are contained in which band? [Learning Outcome: 7-3, Level 1]

A band

Choose the correct statement regarding motor units. A) Muscle fibers of each motor unit are not mingled with those of other motor units. B) During a sustained contraction, all motor units are activated simultaneously. C) A motor neuron may control only two or three muscle fibers of the eye muscle(s). D) When muscles contract for sustained periods, maximal tension is maintained. E) Most motor neurons control fewer than five muscle fibers.

A motor neuron may control only two or three muscle fibers of the eye muscle(s).

Which statement regarding "heat loss" is true? A) Muscle activity does not generate heat. B) Shivering in a cold environment results in higher levels of heat loss. C) When skeletal muscles are contracting at peak levels, body temperature drops. D) Heat loss is reduced when blood flow to the skin increases. E) Muscle contractions play an important role in the maintenance of normal body temperature.

Muscle contractions play an important role in the maintenance of normal body temperature.

Which statement regarding the relaxation phase of a muscle twitch is true? A) The phase begins at stimulation and typically lasts about two milliseconds. B) Muscle tension falls to resting levels. C) The action potential sweeps across the sarcomere during this period. D) Tension rises to a peak. E) Cross-bridges are interacting with active sites on actin filaments throughout this period.

Muscle tension falls to resting levels.

The striated appearance of skeletal muscle results from A) the transverse tubule pattern. B) the sarcoplasmic reticulum. C) cisternae placement. D) actin and myosin arrangement. E) the perimysium arrangement.

actin and myosin arrangement

Fast fibers A) have loosely packed myofibrils. B) have a high concentration of myoglobin. C) have many mitochondria. D) have high glycogen reserves. E) are about half the diameter of slow fibers.

have high glycogen reserves

Skeletal muscle fibers differ from "typical cells" in that these muscle fibers A) lack a plasma membrane. B) have many nuclei. C) are very small. D) lack mitochondria. E) contain endoplasmic reticulum.

have many nuclei

The term used to describe muscular growth in response to usage is A) multiple sclerosis. B) muscular dystrophy. C) atrophy. D) hypertrophy. E) myopathy.

hypertrophy

A muscle producing almost peak tension during rapid cycles of contraction and relaxation is said to be in __________. [Learning Outcome: 7-5, Level 1]

incomplete tetanus

Which of the following occurs as a result of motor units in a particular muscle being always active, even though their contractions do not produce enough movement to cause contraction? A) treppe B) tetany C) muscle tone D) fatigue E) a twitch

muscle tone

Which of the following stabilizes the positions of bones and joints by tensing and firming the muscle? [Learning Outcome: 7-5, Level 1]

muscle tone

After death, rigor mortis lasts until A) ATP is produced. B) T-tubules recapture calcium ions. C) sodium ions are released by the sarcoplasmic reticulum. D) sarcomeres lengthen. E) myofilaments are broken down.

myofilaments are broken down.

The additional oxygen required during the recovery period to restore the normal pre-exertion levels is called the A) oxygen debt. B) refractory oxygen amount. C) anaerobic oxygen threshold. D) aerobic oxygen threshold. E) aerobic oxygen conversion.

oxygen debt

Muscle fascicles are separated by A) endomysium. B) perimysium. C) epimysium. D) sarcolemma. E) periosteum.

perimysium