A&P - Test 3 Review

Which muscles are called muscle cells? Which are elongated

Skeletal and smooth muscle cells (not cardiac) are elongated and are called muscle fibers

What is the longest types of muscle cells?

skeletal

is skeletal muscle voluntary?

Yes - only subject to conscious control

Which type of muscle is striated and voluntary?

Skeletal

Which type of muscle is striated and involuntary?

Cardiac

Which type of muscle is visceral, nonstriated, and involuntary?

smooth

Movement, maintain posturem stabilize joints, and heat generation are all functions of what?

Muscle

Skeletal muscle cells are also referred to as?

a) Striations

b) Sarcolemmas

c) Muscle fibers

d) Involuntary muscle cells

c) Muscle fibers

Which of the following is NOT a normal function of muscle tissue?

maintaining posture

generating heat

secreting hormones       

stabilizing joints

producing movement

secreting hormones       

Which of the following are correctly paired?

skeletal muscle; voluntary control

cardiac muscle; voluntary control

cardiac muscle; nonstriated

smooth muscle; striated

skeletal muscle; voluntary control

The ability of muscle to shorten forcibly when adequately stimulated is known as ________, and sets muscle apart from other tissue types.

excitability

elasticity

contractility

extensibility

contractility

_________ The ability to receive and respond to stimuli (shared by neurons as well).

Excitability

______ The ability to recoil to resting length after stretching.

Elasticity

________ The ability to be stretched or extended.

Extensibility

Which of the following properties is most directly associated with changes to a muscle cell's membrane potential (the voltage across the plasma membrane)?

contractility

extensibility

elasticity

excitability

excitability

________, also termed responsiveness, is the ability of a cell to receive and respond to a stimulus by changing its membrane potential. For example, a neurotransmitter released by a nerve cell may cause the depolarization of the muscle cell's sarcolemma

Excitability

Which connective tissue surrounds the whole muscle?

1) Epimysium

2) Endomysium

3) Perimysium

1) Epimysium

the _______ is the outermost muscle sheath, which encloses the entire muscle

Epimysium

Which of the following is NOT found within a skeletal muscle?

a) Blood vessels

b) Connective tissue proper

c) nervous tissue

d) Osseous tissue

Osseous tissue

Which structure in the figure corresponds to a single skeletal muscle cell?

C

a skeletal muscle cell is commonly termed a ?

muscle fiber

Which of the following corresponds to a single fascicle?

B

A _______ is an organized group of muscle fibers (cells).

fascicle

Which term best identifies a skeletal muscle cell?

muscle fiber

myofibril

sarcomere

muscle fascicle

muscle fiber

_____ muscle cells fuse during development to form the mature, multinucleated muscle fibers.

Skeletal

Which of the following surrounds an individual muscle cell?

fascicle

perimysium

endomysium

epimysium

endomysium

Which of the following is the smallest structual unit?

a) Myofilament

b) Fascicle

c) Myofibril

d) Muscle fiber

e) Sarcomere

a) Myofilament

Which one of the following structures is incorrectly paired?

a) Sarcoplasmic reticulum - membranous organelle that stores and releases calcium ions

b) Sarcomere - bordered at the end of by a Z disc

c) T-tubule - extension of the sarcolemma

d) A band - composed mostly of protein actin

d) A band - composed mostly of protein actin

Which of the following does NOT change length during shortening results from muscle contraction?

a) The H zone

b) The distance between Z discs

c) Thin myofilaments

d) The I band

c) Thin myofilaments

Which muscle cell structure stores calcium ions that are used to trigger the contraction?

the sarcoplasmic reticulum

the myofibril

the sarcolemma

glycosome

the sarcoplasmic reticulum

The ____________ is an intracellular organelle that stores and releases calcium ions into the sarcoplasm (cytoplasm of a muscle cell).

sarcoplasmic reticulum

___________: Contains the contractile proteins (actin and myosin), but does not store calcium.

Myofibril

___________: The plasma membrane of a muscle cell — it conducts action potentials but doesn't store calcium.

Sarcolemma

_______: Organelles that store glycogen, not calcium.

Glycosome

The contractile, or functional, unit of a muscle fiber is __________.

troponin

the myofilament

the elastic filament

the sarcomere

the sarcomere

The sarcomere is the contractile unit of a muscle fiber and the _____ functional unit of muscle.

smallest

A sarcomere is the region of a myofibril between two successive ?

Z discs

The _____ primarily consists of thin and thick myofilaments.

sarcomere

The sliding filament model of contraction states that __________.

during contraction, the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments no longer overlap

during contraction, the thin myofilaments slide past T tubules so that the Z discs are overlapping

during contraction, the thin myofilaments slide past the thick myofilaments so that calcium ions can be released from the sarcoplasmic reticulum

during contraction, the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree

during contraction, the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree

In a relaxed muscle fiber, the thick and thin myofilaments overlap only at the ends of the?

A band.

Label the following

(Z Disc, M Line, A Band, H Zone, I Band

A) Z disc

B) H zone

C) I Band

D) A BAnd

E) M Line

What is the role of tropomyosin in skeletal muscles?

Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

Tropomyosin is the receptor for the motor neuron neurotransmitter.

Tropomyosin is the chemical that activates the myosin heads.

Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules.

Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

Label the following:

(T Tubule, Myofibrils, I Band, Triad, Sarcolemma, A band, terminal cisterns)

A) T tubule

B) A Band

C) I Band

D) Sarcolemma

E) Triad

F) Terminal cisterns

G) Myofibrils

Voltage gated Na⁺ and K₊ channels are associated directly with which of the following events during stimulation of a muscle fiber?

a) Release of ACh into the synaptic cleft

b) Propagating the AP along the sarcolemma

c) End plate potential at the junctional folds

d) Release of Ca²⁺ from the SR

b) Propagating the AP along the sarcolemma

Which of the following occurs last among the events that trigger cross bridge formation?

a) Arrival of an AP at the axon terminal of a motor neuron

b) binding of ACh to receptors

c) Depolarization of the sarcolemma

d) Binding of Ca²⁺ to troponin

d) Binding of Ca²⁺ to troponin

place in the correct order of occurrence from left to right the events that occur at the neuromuscular junction after the action potential reaches the axon terminal

Which of the following is/are mechanism(s) to end neural transmission at the neuromuscular junction?

ACh is taken up by the axon terminal via endocytosis.

ACh is broken down into acetic acid and choline by the enzyme acetylcholinesterase (AChE).

ACh diffuses away from the synaptic cleft.

ACh binds to ACh receptors.

ACh is broken down into acetic acid and choline by the enzyme acetylcholinesterase (AChE).

ACh diffuses away from the synaptic cleft.

What event directly triggers the release of neurotransmitter shown in A?

diffusion of Ca²⁺ into the axon terminal

diffusion of Na⁺ out of the axon terminal

diffusion of K⁺ into the axon terminal

diffusion of Na⁺ into the axon terminal

diffusion of Ca²⁺ into the axon terminal

A nerve impulse arrives at the axon terminal triggering the opening of Ca²⁺ channels, which allows for the diffusion of Ca²⁺ into the terminal. This in turn leads directly to the release of neurotransmitters by _______.

exocytosis

Which statement accurately describes the event indicated by B?

Diffusion of acetylcholine into the muscle fiber triggers the opening of an ion channel.

Binding of acetylcholine to a receptor triggers the opening of an ion channel.

The binding of acetylcholine directly causes the formation of a wave of depolarization.

Diffusion of Ca²⁺ into the muscle fiber triggers the diffusion of acetylcholine out of the muscle fiber.

Binding of acetylcholine to a receptor triggers the opening of an ion channel.

Binding of acetylcholine to its receptor opens chemically (ligand) gated ion channels that allow Na⁺ and K⁺ to diffuse across the ?

sarcolemma

Which step precedes all of the other listed steps?

The sarcoplasmic reticulum is activated.

Na⁺ rushes into the cell.

An action potential starts on the sarcolemma.

ACh is released by the motor neuron.

ACh is released by the motor neuron.

The first step toward generating a skeletal muscle contraction is nervous stimulation of the muscle fiber in order to ?

generate an action potential.

The site of muscle stimulation, where the nerve ending communicates with the muscle fiber, is called the ?

neuromuscular junction.

Place the events that occur during excitation-contraction coupling in the correct order from left to right.

Consider how the action potential that initiates contraction is delivered to the muscle cell.

Which of the choices below correctly describes how an action potential generated at the neuromuscular junction (NMJ) is converted to excitation in the muscle fiber?

An action potential in the motor neuron directly triggers an action potential at the sarcolemma.

An action potential in the motor neuron causes ACh to be released into the synaptic cleft. Binding of ACh to sarcolemma receptors initiates graded potentials.

ACh binds at a receptor in the motor neuron, which initiates graded potentials.

An action potential in the motor neuron causes ACh to be released into the synaptic cleft. Binding of ACh at the membrane receptor initiates a direct action potential.

An action potential in the motor neuron causes ACh to be released into the synaptic cleft. Binding of ACh to sarcolemma receptors initiates graded potentials.

The action potential propagates along the sarcolemma. As the action potential spreads down the T tubules of the triads, voltage-sensitive tubule proteins change shape.

How does the shape change of these proteins lead to contraction?

It allows calcium to exit the cytoplasm and enter the cisterns.

It facilitates ACh's binding to the sarcolemma.

It permits calcium to exit the cistern and enter the T tubule.

It allows calcium to exit the sarcoplasmic reticulum and enter the cytosol

It allows calcium to exit the sarcoplasmic reticulum and enter the cytosol.

As the action potential propagates, it changes the shape of _______ proteins.

These proteins are linked to calcium channels in the terminal cisterns of the sarcoplasmic reticulum. When these proteins' calcium channels open, a massive amount of _____ flows into the cytosol.

T tubule

calcium

Match the following of the muscle cell

(Sarcolemma, T-tubule, terminal cistern, Ca ions, Voltage sensitive tubule protein)

A) Ca ions

B) Voltage-sensitive tube protein

C) T tubule

D) Sarcolemma

E) Terminal cistern

Which selection correctly describes the role of calcium in coupling?

Calcium binds to troponin, which moves tropomyosin and exposes the myosin-binding sites on actin.

Calcium binds to actin, which triggers it to bind to myosin.

Calcium binds to actin, which triggers troponin to fall off and expose myosin-binding sites.

Calcium binds to tropomyosin, which moves tropomyosin and exposes the myosin-binding sites on actin.

Calcium binds to troponin, which moves tropomyosin and exposes the myosin-binding sites on actin.

Which selection best describes the initial event in contraction?

Calcium binds actin to myosin to begin the cross bridge cycle.

Tropomyosin binds to myosin heads and actin bridges with tropomyosin.

Myosin heads bind to the newly exposed myosin-binding sites on actin to form cross bridges.

The myofilaments slide closer together.

Myosin heads bind to the newly exposed myosin-binding sites on actin to form cross bridges.

Match the following

1) Cistern

2) Voltage-sensitive tubule protein

3) Myosin

4) T Tubule

5) Troponin

Put the following in order of the correct occurrence of the excitation-contraction coupling

Coupling begins with an action potential after the arrival of ACh and graded potentials, and it ends before ?

cross bridge cycling.

Which of the following choices best summarizes excitation-contraction coupling?

A series of events in which an action potential triggers the release of chemical messengers

A series of events in which an electrical stimulus is conveyed to a muscle fiber to enact contraction

A series of events in which actin binds myosin to enact contraction

A series of events in which calcium gradients are used to convey a signal to the muscle fiber to enact contraction

A series of events in which an electrical stimulus is conveyed to a muscle fiber to enact contraction

The cross bridge cycle starts when _________.

acetylcholine diffuses away from the synaptic cleft

Ca²⁺ from the sarcoplasmic reticulum binds to tropomyosin

Ca²⁺ is actively transported into the sarcoplasmic reticulum

Ca²⁺ from the sarcoplasmic reticulum binds to troponin

ATP binds to troponin and is hydrolyzed to ADP and P_i

Place the steps that occur during a single cross bridge cycle in the correct order from left to right.

Which protein is indicated by the letter A?

troponin

actin

myosin

keratin

actin

_____ is the chief component of the thin myofilaments. It is made of a set of globular proteins attached in a chain.

Actin

Which of the following occurs during the relation phase of a muscle twitch?

a) Release of ACh into the synaptic cleft

b) Binding of Ca²⁺ to thin filaments

c) active transport of Ca²⁺ into the SR

d) Depolarization of T tubules

Actin

Increased contractile force due to recruitment results from?

a) Stimulation of muscle by increasing numbers of activated somatic motor neurons

b) Increasing frequency of muscle fiber stimulation by somatic motor neurons

c) Electrical signals traveling from one muscle fiber to adjacent fibers

d) increasing the amplitude of action potentials arriving at the neuromuscular junction along somatic motor neurons

a) Stimulation of muscle by increasing numbers of activated somatic motor neurons

Each neuron shown in this figure innervates a group of muscle fibers. What is the term for a group of muscle fibers and the single neuron that innervates them?

neuromuscular junction

sarcomere

motor unit

fascicle

motor unit

If both of the neurons in the figure were activated, more muscle fibers would contract than if either neuron alone were active. This mechanism for control of the force of muscle contraction is known as __________.

wave summation

recruitment

tetanus

excitation-contraction coupling

recruitment

Recruitment refers to the increased force generated by the activation of increasing numbers of _____ units.

motor

In which phase in the figure would the net movement of

Ca²⁺ INTO the sarcoplasmic reticulum (SR) be greatest?

C

What result would be expected if an additional stimulus, equal in intensity to the first, were to be applied to the muscle at the 60 millisecond (ms) time point?

The muscle would quickly return to the fully relaxed state of minimum tension.

The muscle would increase in tension to a level greater than that measured at the beginning of phase C.

Tension would increase to the same maximum force measured at the beginning of phase C.

The tension exerted by the muscle would continue to decrease, but at a significantly slower rate than observed without the second stimulus.

The muscle would increase in tension to a level greater than that measured at the beginning of phase C.

A muscle that is lengthening while it produces tension is performing a(n) __________ contraction.

concentric

eccentric

isometric

maximal

eccentric

We use _______ contractions to lower objects (such as lowering a book from the shelf or lowering the barbell during a bench press).

eccentric

Muscle tone is ________.

the ability of a muscle to efficiently cause skeletal movements

a state of sustained partial contraction

the condition of athletes after intensive training

the feeling of well-being following exercise

a state of sustained partial contraction

which of the following is expected to occur during the recovery period following exercise?

a) ATP is synthesized anaerobically

b) Pyruvate is converted to lactate

c) Oxygen levels in muscle tissue decrease

d) Glycogen is formed from glucose

d) Glycogen is formed from glucose

What ATP regeneration pathway is used first during skeletal muscle contraction?

aerobic respiration

anaerobic glycolysis

breakdown of stored glycogen

direct phosphorylation of ADP by creatine phosphate

direct phosphorylation of ADP by creatine phosphate

Which of the following statements is NOT true regarding ATP production in muscles during periods of prolonged energy use, such as exercise?

Prolonged activity requires the use of aerobic pathways for ATP regeneration.

As your blood sugar drops at any time during prolonged activity, glycogen stores in your muscles can be broken down to supply a glucose source.

In the absence of oxygen, creatine phosphate can drive aerobic respiration pathways for a few minutes.

In the absence of oxygen, anaerobic pathways provide minimal ATP regeneration for less than a minute.

In the absence of oxygen, creatine phosphate can drive aerobic respiration pathways for a few minutes.

During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________.

lactic acid

a strong base

stearic acid

hydrochloric acid

lactic acid

Which of the following explains the decreased contractile force generated by the stretched muscle?

a) The stretched muscle fibers are less sensitive to stimulation by ACh

b) Stretching of myofibrils within the muscle fibers decreases the overlap between thin and thick myofilaments

c) AP’s weaken as they travel increasing distances along stretched muscle fibers

d) Muscle fibers begin to separate from each other within the stretched muscle

b) Stretching of myofibrils within the muscle fibers decreases the overlap between thin and thick myofilaments

which of the following is NOT a characteristic of fast glycolytic fibers?

a) White appearance

b) Relatively large fiber diameter

c) Depend on blood-delivered nutrients

d) Powerful contraction but quick fatigue

c) Depend on blood-delivered nutrients

Which of the following factors influence the velocity and duration of muscle contraction?

length of muscle fibers activated

muscle fiber size

frequency of stimulation

load placed on the muscle

load placed on the muscle

Speed (velocity) of shortening is a function of load and muscle-fiber type. Contraction is fastest when the load on the muscle is zero; a ______ load results in a slower contraction and a shorter duration of contraction.

greater

Which muscle fiber type is best suited for endurance activities, such as long-distance jogging?

fast oxidative fibers

slow oxidative fibers

slow glycolytic fibers

fast glycolytic fibers

slow oxidative fibers

____ _______ fibers are best suited for endurance activities because they produce ATP aerobically and are fatigue-resistant.

Slow oxidative

The force of a muscle contraction is NOT affected by __________.

the number of muscle fibers stimulated

the frequency of the stimulation

the amount of ATP stored in the muscle cells

the size of the muscle fibers stimulated

the degree of muscle stretch

the amount of ATP stored in the muscle cells

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

True

False

False

In a bedridden patient recovering from a badly fractured femur, disuse atrophy in the thigh muscles is caused by _________.

decreased ability of muscle cells to produce ATP, resulting in decreased ability of the muscles to contract

decreased ability to synthesize acetylcholine in the neurons that innervate the thigh muscles

decreased synthesis of muscle proteins and/or increased breakdown of muscle proteins

none of the above

decreased synthesis of muscle proteins and/or increased breakdown of muscle proteins

Muscle tissue grows and heals in response to stress. Without the stress of exercise and normal daily activities, muscle tissue _______?

degenerates

Which of the following statements accurately describes a similarity between smooth and skeletal muscles?

a) Initiation of contraction in both smooth and skeletal muscle contraction depends on invalid expression binding to troponin

b) Both smooth muscle and skeletal muscle are striated

c) Both smooth muscle and skeletal muscle are arranged in longitudinal and circular layers

d) Both smooth muscle and skeletal muscle contain thin and thick myofilaments

d) Both smooth muscle and skeletal muscle contain thin and thick myofilaments

What feature of smooth muscle allows it to stretch without immediately resulting in a strong contraction?

smooth muscle tone

low energy requirements

stress-relaxation response

slow, prolonged contractile activity

stress-relaxation response

Which of the following is true?

Smooth muscle lacks the thin and thick filaments characteristic of skeletal muscle.

Skeletal muscle lacks the coarse connective tissue sheaths that are found in smooth muscle.

Skeletal muscle fibers tend to be shorter than smooth muscle fibers.

Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not.

Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not.

Which type of muscle is found in the body wall of hollow organs?

unitary smooth muscle

skeletal muscle

multi unit smooth muscle

cardiac muscle

unitary smooth muscle

Smooth muscle is generally classified as either unitary smooth muscle or multi unit smooth muscle. The type of muscle found in the walls of most hollow organs is?

unitary smooth muscle.

The mechanism of contraction in smooth muscle is different from skeletal muscle in that ________.

actin and myosin interact by the sliding filament mechanism

the site of calcium binding site differs

ATP energizes the sliding process

the trigger for contraction is a rise in intracellular calcium

the site of calcium binding site differs

An entire skeletal muscle is surrounded by __________.

perimysium

epimysium

endomysium

tendon sheath

sarcolemma

epimysium