Muscular System Chapter 9

The elastic filaments within a myofibril are attached to and wound around, . . .

Myosin

Bundles of muscle fibers (fascicles) are wrapped by a tissue known as

Perimysium

Thin filaments within the myofibril are composed primarily of

Actin

The tissue that surrounds a muscle cell (myofiber) is known as

Endomysium

The cytoplasm within the muscle fiber contains a molecule to distribute oxygen within the cell. This molecule is known as

myoglobin

When the myosin head (of the thick filament) flexes into a bend, while releasing ADP and inorganic phosphate, pulling the thin filament along with it, this is called the

power stroke

The cytoplasm within the muscle fiber is known as the

sarcoplasm

A buildup of acetylcholine in the synaptic cleft without breakdown may cause which of the following? A) spastic paralysis B) treppe C) myasthenia gravis D) flaccid paralysis

spastic paralysis

The functional connection between a nerve fiber and a muscle fiber is called a(an) A) T tubule. B) I band. C) synapse. D) troponin-myosin component.

synapse.

Which protein attaches Z discs to myosin myofilaments?

titin

When acetylcholine is broken down by acetylcholinesterase in the synaptic cleft, what happens to the choline? A) It is destroyed. B) It is made into new acetylcholinesterase. C) It is reabsorbed at the presynaptic terminal and combined with more acetic acid to make acetylcholine. D) It is taken up at the postsynaptic terminal.

It is reabsorbed at the presynaptic terminal and combined with more acetic acid to make acetylcholine.

Which of the following best describes the use of muscle tone in the body? A) It keeps heart muscle activated and functional. B) It keeps smooth muscles in a ready state. C) It prevents fatigue. D) It keeps our backs straight and our heads up.

It keeps our backs straight and our heads up

The "all-or-none" concept of skeletal muscle contraction means that A) all muscles contract completely and not partially. B) muscle fascicles contract completely. C) muscle fibers contract completely. D) all of the actin and myosin molecules contract.

Muscle fibers contract completely.

In the myofibril, ATP is used for which of the following? A) muscle tone B) muscle contraction C) muscle relaxation D) All of the above.

Muscle tone, muscle contraction, muscle relaxation all of the above

One of the characteristics of muscle tissue is that is has extensibility. Which of the following best describes this characteristic? A) Muscles contract when stimulated. B) Muscles have local electrical charges that move along the muscle fiber. C) Muscles only pull; they cannot push. D) Muscles can stretch when needed.

Muscles can stretch when needed

One of the characteristics of muscle tissue is that is has excitability. Which of the following best describes this characteristic? A) Muscles contract when stimulated. B) Muscles have local electrical charges that move along the muscle fiber. C) Muscles only pull; they cannot push. D) Muscles can stretch when needed.

Muscles contract when stimulated.

One of the characteristics of muscle tissue is that is has conductivity. Which of the following best describes this characteristic? A) Muscles contract when stimulated. B) Muscles have local electrical charges that are capable of moving along the muscle fiber. C) Muscles only pull; they cannot push. D) Muscles can stretch when needed.

Muscles have local electrical charges that are capable of moving along the muscle fiber.

Objects that move through organs that are surrounded by smooth muscle are often moved by means of

Peristalsis

Which of the following is true about distribution of fast and slow-twitch fibers in the body? A) Fast-twitch fibers are primarily found in long distance runners. B) Slow-twitch fibers are usually more resistant to fatigue. C) There is a clear separation of slow- and fast-twitch fibers in individual muscles. D) Training does not influence the balance of fast- and slow-twitch fibers.

Slow-twitch fibers are usually more resistant to fatigue

Which of the following tissues has the greatest ability to repair itself? A) skeletal muscle B) cardiac muscle C) smooth muscle D) all have about the same ability

Smooth muscle

What exercises slows the loss of muscle fibers in oler people?

Swimming

Which of the following is true of an isometric muscle contraction? A) The length of the muscle increases during the contraction. B) responsible for rapid movements of the extremities C) divided into concentric and eccentric D) The amount of tension increases during the contraction.

The amount of tension increases during the contraction

During an action potential, calcium is released into the sarcoplasm, near the actin and myosin molecules. Which of the following is the best explanation of what the calcium does? A) The calcium binds to the actin and myosin and makes them work together. B) The calcium breaks apart ATP to ADP and P. C) The calcium removes the tropomyosin block. D) The calcium causes the release of acetylcholine.

The calcium removes the tropomyosin block

Which of the following is unique about cardiac muscle tissue? A) The cells have large mitochondria. B) The cells are large and wide. C) There are very few nuclei within the cells. D) There is no neuron innervation.

The cells have large mitochondria

Which of the following is true about skeletal muscle fibers in aging people? A) The number of fibers decreases. B) There is a decreased density of capillaries that supply muscle cells. C) The number of motor neurons that innervate skeletal muscle decreases. D) All of the above.

The number of fibers decreases, there is a decreased density of capillaries that supply muscle cells, the number of motor neurons that innervate skeletal muscle decreases.

Which of the following is true about smooth muscle? A) The resting membrane potential is less negative than in skeletal muscle. B) It responds in an "all or none" fashion. C) It does not respond to hormones. D) It has a faster speed of contraction than skeletal muscle.

The resting membrane potential is less negative than in skeletal muscle

Which of the following best describes the function of the series-elastic component of muscle? A) These components help the muscle contract. B) The components help maintain muscle tone. C) These are not excitable or contractile, but are extensible and elastic. D) These assist the thick and thin filaments to contract.

These are not excitable or contractile, but are extensible and elastic.

The elastic filaments within a myofibril are composed of molecules known as

Titin

Eccentric muscle contractions occur when A) a person slowly lowers a heavy weight B) the length of the muscle does not change C) a person rapidly raises a lighter weight D) the length of the muscle decreases

a person slowly lowers a heavy weight

When the neuron stimulates a muscle fiber, what molecule diffuses across the gap between them?

acetylcholine

Which of the following is a molecule that binds to a receptor? A) acetylcholine B) tropomyosin C) acetylcholinesterase D) all of the above

acetylcholine

What are the most common neurotransmitters in smooth muscle?

acetylcholine and norepinephrine

Which of the following assures quick removal of neurotransmitter at the junction between a nerve and a muscle? A) acetylcholine B) dopamine C) acetylcholinesterase D) PABA

acetylcholinesterase

On the surface of the sarcolemma, the voltage may shift up and down rapidly. This change in electrical potential caused by shifts in ions across the membrane is known as a(n)

action potential

The striations in striated muscle correspond with actual molecular structures. Which of the following is the Z line? A) a band where only actin molecules are found B) a band where only myosin molecules are found C) an attachment point for actin molecules D) an attachment point for myosin molecules

an attachment point for actin molecules

Smooth body movements result from A) large numbers of motor units in complete tetanus throughout the contraction. B) small numbers of motor units firing in a "single twitch" fashion simultaneously. C) isometric contractions only. D) both incomplete and complete titanic contractions of motor units contracting out of phase with each other.

both incomplete and complete titanic contractions of motor units contracting out of phase with each other.

Once a signal molecule has left the neuron and binds to a receptor molecule on the surface of the muscle fiber, a sodium channel opens, allowing entry of sodium into the muscle fiber. Which substance is then released from the sarcoplasmic reticulum?

calcium

Which of the following energy storages source is most commonly used during the first 10 seconds of exercise? A) ATP B) creatine phosphate C) lactic acid D) none of the above

creatine phosphate

All of the following are true of muscle tone except A) exists for long periods of time B) depends on multiple motor units contracting in phase with each other C) helps maintain the head upright D) Tension in the whole muscle remains constant.

depends on multiple motor units contracting in phase with each other

A person with an arm immobilized in a cast for 6 weeks will A) develop muscular hypertrophy. B) decrease the number of muscle fibers. C) develop muscular atrophy. D) Both B and C.

develop muscular atrophy.

Which of the following effects of exercise elevate the body temperature? A) elevated metabolism from the oxygen debt B) vasodilation of blood vessels in the skin C) skeletal muscle contractions D) all of the above

elevated metabolism from the oxygen debt, vasodilation of blood vessels in the skin, skeletal muscle contractions.

The ability of a muscle to be stimulated is called

excitability

The molecule within the cytoplasm of a muscle fiber that supplies quick energy for contraction is

glycogen

Which of the following is one of the primary functions of muscle tissue? A) regeneration of mass B) heat production C) growth D) the ability to last forever

heat production

All of the following are true about fast-twitch fibers except A) high amount of myoglobin B) rapid contraction C) break down ATP rapidly D) fewer mitochondria than slow-twitch fibers

high amount of myoglobin

Which of the following explains why treppe takes place in muscle contractions? A) decreased calcium levels around the myofibrils B) increased sodium around the myofibrils C) increased calcium levels around the myofibrils D) decreased potassium around the myofibrils

increased calcium levels around the myofibrils

Which of the following is not an effect of aging on skeletal muscle? A) increased time for muscle to respond to stimuli B) increased myoglobin C) increased recovery time D) loss of muscle fibers

increased myoglobin

The tissues of cardiac muscle have unique structures known as A) circular muscle fibers B) abundant elastic fibers C) intercalated discs D) pacemaker cells

intercalated discs

In a muscle twitch, which of the following represents the time between application of a stimulus and the beginning of contraction? A) treppe B) tetany C) lag D) relaxation

lag

All of the following are characteristics of slow-twitch fibers except A) slow contraction. B) large diameter. C) good blood supply. D) many mitochondria.

large diameter.

Which of the following would represent incomplete tetanus? A) multiple contractions with no relaxation B) multiple contractions with slight relaxation C) multiple contractions followed by a long rest period D) a long rest period before contractions start

multiple contractions with slight relaxation

What part of a muscle is the muscle fiber? A) actin and myosin component B) series-elastic component C) muscle cell itself D) nuclei and the mitochondria

muscle cell itself

Which type of muscle fatigue represents depletion of ATP?

muscular

Muscle soreness can be produced by which of the following? A) muscular fatigue B) enzymes in the extracellular fluid commonly found within muscle C) collagen in the extracellular fluid D) all of the above

muscular fatigue, enzymes in the extracellular fluid commonly found within muscle, collagen in the extracellular fluid

Which of the following is the A band within a myofibril? A) actin myofilaments in profile B) myosin myofilaments in profile C) Z disks in profile D) gaps between the actin and myosin myofilaments

myosin myofilaments in profile

Which of the following best describes a muscle motor unit? A) a section of myofibrils from Z lines to Z lines B) one nerve fiber and all the muscle fibers innervated by that nerve C) all of the nerves that unite to make a whole muscle contract D) all of the fascicles innervated by several neurons

one nerve fiber and all the muscle fibers innervated by that nerve

Binding of acetylcholine with its receptor on muscle cells causes A) opening of a ligand-gated sodium channel B) a gap in the cell membrane for calcium diffusion C) vesicle release of sodium ions D) opening of a ligand-gated calcium channel

opening of a ligand-gated sodium channel

Which of the following represents the amount of oxygen that is necessary for the body to recover from anaerobic respiration? A) creatine phosphate utilization period B) oxygen overload C) oxygen debt D) aerobic respiration

oxygen debt

Intercalated discs are capable of doing which of the following? A) allow for re-growth of damaged muscle cells B) pass the resting potential to other cardiac cells C) pass electrical stimulation to other cardiac cells D) allow for cardiac tissue to expand and contract properly

pass electrical stimulation to other cardiac cells

Which of the following represents extreme muscular fatigue when the muscle is incapable of either contracting or relaxing? A) physiological contracture B) physiological contraction C) psychological fatigue D) synaptic fatigue

physiological contracture

The recovery stroke in muscle contraction involves which of the following? A) movement of the myosin molecule while the cross-bridge is attached B) return of the myosin head to its original position after the cross bridge releases C) actin slides on myosin D) myosin slides on actin

return of the myosin head to its original position after the cross bridge releases

The outer membrane of the muscle fiber is known as the

sarcolemma

Which of the following is the unit in a myofibril from Z line to Z line?

sarcomere

Which of the following muscle types contains peripherally located, multiple nuclei in its cells?

skeletal

Of the following muscles types, which one has long, cylindrical-shaped cells?

skeletal muscle

Which of the following muscles is involuntary and is the most widely found throughout the body?

smooth

What type of fatigue is caused by the release of more acetylcholine than can be produced to replace it?

synaptic

Which of the following determines the height of the peaks in multiple motor unit summation? A) the speed of stimuli B) the amount of tension produced by the number of motor units responding C) the strength of each stimulus D) none of the above

the amount of tension produced by the number of motor units responding

Active tension in a muscle is defined as A) the tension applied to load when the muscle is stretched but not stimulated. B) the tension applied to a load when myofilaments within sarcomeres minimally overlap. C) the tension applied to a load when the muscle contracts. D) muscle contraction produced wholly from complete tetanus.

the tension applied to a load when the muscle contracts.

Muscle fibers and neurons are called electrically excitable cells because A) their membranes respond to electricity B) their plasma membranes exhibit voltage changes in response to stimulation C) their surfaces respond to the release of acetylcholine D) they have junctional folds in the membranes that can trap electrical charges

their plasma membranes exhibit voltage changes in response to stimulation

The sum of active and passive tension is called

total tension.

Movement of what protein causes exposure of the active sites on the actin molecule?

tropomyosin

Triads in skeletal muscle consist of which of the following? A) sarcoplasm, sarcoplasmic reticulum, calcium ions B) sarcoplasmic reticulum, terminal cisterna, sarcoplasm C) two terminal cisternae and a T-tubule. D) two T-tubules and one terminal cisterna

two terminal cisternae and a T-tubule.

Which of the following groups are considered to be parts of the series-elastic components of muscle? A) actin and myosin B) ligaments and tendons C) thick and thin filaments D) endomysium, perimysium, epimysium, fascia, and tendons

Endomysium, perimysium, epimysium, fascia, and tendons.

A connective tissue on the surface of muscles (that extends onto the tendon and bone) is known as

Fascia

Muscle fibers are bundled into groups known as

Fascicles

What is the voltage of the resting potential of the sarcolemma?

-70 mv

During anaerobic respiration, what is the net amount of ATP produced?

2 ATP

Unitary smooth muscle is found in which of the following locations in the body? A) digestive tract B) reproductive tract C) urinary tract D) all of the above

Digestive tract, reproductive tract, urinary tract.

The tissue surrounding an entire muscle is known as

Epimysium

In the muscle fiber, what is the function of acetylcholinesterase?

It deactivates acetylcholine.

Which of the following is TRUE of cardiac tissue? A) It contains only small amounts of myoglobin and glycogen. B) It has few nerve endings within the tissue. C) The fibers are not arranged in bundles. D) It has abundant glycogen and myoglobin and is aerobic

It has abundant glycogen and myoglobin and is aerobic

What type of molecule is acetylcholine?

It is a neurotransmitter.

Thick filaments within the myofibril are composed of

Myosin

The myofilaments within the muscle fiber are composed of three integral items.

Myosin, actin, and elastic (titin) filament.

Which muscle type is usually voluntary?

Skeletal

Which muscle type does NOT have striations?

Smooth

Which muscle type is found in the middle layer of the aorta?

Smooth

Which muscle types has only one nucleus?

Smooth

Action potential frequency is best described as: A) The strength of the muscle contractions. B) The size of the muscle contracting. C) The speed of muscle contractions D) The number of action potentials produced per unit of time.

The number of action potentials produced per unit of time.

When the thick and the thin filaments pull together, which of the following is TRUE? A) The Z to Z line unit moves apart. B) The myofibril doubles in size. C) The muscle loses tone. D) The sarcomere gets shorter.

The sarcomere gets shorter.

The striations in striated muscle correspond with actual molecular structures. Which of the following is the I band? A) a band where only actin molecules are found B) a band where only myosin molecules are found C) an attachment point for actin molecules D) an attachment point for myosin molecules

a band where only actin molecules are found

The striations in striated muscle correspond with actual molecular structures. Which of the following is the H band? A) a band where only actin molecules are found B) a band where only myosin molecules are found C) an attachment point for actin molecules D) an attachment point for myosin molecules

a band where only myosin molecules are found

Which of the following types of muscles contain intercalated discs and branching fibers?

cardiac

What kind of molecule is ACh? A) nucleic acid B) protein C) carbohydrate D) lipid

protein

All of the following are properties of cardiac muscle cells except A) intercalated discs B) involuntary C) branching fibers D) shorter in duration of contraction than skeletal muscles.

shorter in duration of contraction than skeletal muscles.