Human Anatomy: Chapter 10 - Skeletal Muscle Tissue

Which of the following describes the functional characteristic of muscle called elasticity? (IMPORTANT)

After being stretched, muscle tissue can passively recoil and resume its resting length.

Muscle tissue has which of the following functions? Movement Joint stabilization Heat generation All of these

All of these

Skeletal muscle cells have which of the following characteristics? (IMPORTANT) They are long and cylindrical. Their diameter is 10-100µm. They are multinucleate. They are long and cylindrical and multinucleate. All of these.

All of these.

Which of the following are important similarities among skeletal, cardiac, and smooth muscle? (IMPORTANT)

All three depend on myofilaments for contraction. Their plasma membrane is called a sarcolemma.

Sarcoplasmic reticulum tubules called "terminal cisterns" form large, perpendicular cross-channels over which junction? (IMPORTANT)

Between each A band in a myofibril and its adjacent I bands

Axon terminals __________.

are clusters of enlarged endings of an axon that may contain neurotransmitters

Which of the following describes the Z disc of the sarcomere? (IMPORTANT)

Boundary of an individual sarcomere; connected to thin filaments and titin

The sarcoplasmic reticulum stores large quantities of which ion? (IMPORTANT)

Ca2+. Calcium ions.

__________ contraction occurs when a muscle generates force as it shortens. (IMPORTANT)

Concentric

The "sliding filament mechanism" explains which type of muscle contraction?

Concentric contraction

a single motor neuron and all muscle fibers it innervates (IMPORTANT)

Define a motor unit.

Regarding muscle attachments, which term(s) indicate(s) that the strands of connective tissue are so short that the muscle fascicles appear to attach directly to the bone? (IMPORTANT)

Direct attachments and fleshy attachments

Which of the following describes a fascicle? (IMPORTANT)

Discrete bundles of muscle cells, segregated from the rest of the muscle by a connective tissue sheath

T tubules ____________. (IMPORTANT)

are deep invaginations of the sarcolemma, and conduct impulses into the deepest region of muscle fibers

Which of the following describes a skeletal muscle fiber? (IMPORTANT)

Elongated, multinucleate cell that has a striated appearance

Why are there fewer muscle fibers per motor unit in the fingers than in the muscles of the thighs?

Fewer muscle fibers per motor unit allows for fine control of muscle action.

Which one of the following describes A band sarcomere? (IMPORTANT)

Full length of thick filaments, including overlapping inner ends of thin filaments

The central part of the "A band" of a sarcomere is known as the __________. (IMPORTANT)

H zone

The region of thin filaments only that is part of two adjacent sarcomeres is the __________. (IMPORTANT)

I band

Which portion of the sarcomere creates the light portions of the light-dark pattern of striations seen along the length of a muscle fiber? (IMPORTANT)

I band

b. T tubule (IMPORTANT)

Identify the structure within the muscle fiber that carries an electrical impulse from the surface membrane deep into the muscle fiber. a. sarcoplasmic reticulum b. T tubule c. Z disc d. terminal cisterna

Which of the following describes functional characteristic of muscle called excitability? (IMPORTANT)

Nerve signals or other factors cause electrical impulses to travel along the cell's sarcolemma, stimulating the cells to contract.

During contraction of a sarcomere, what happens to the A band? (IMPORTANT)

It remains the same length.

During a muscle contraction, which of the following structures actually shorten?

Muscle fiber Muscle fascicle Sarcomere Myofibril

Which of the following describes the functional characteristic of muscle called extensibility? (IMPORTANT)

Muscle tissue can be stretched by the contraction of an opposing muscle.

How does the sliding filament mechanism result in concentric contraction of skeletal muscle? (IMPORTANT)

Myosin heads of thick filaments attach to thin filaments at both ends of a sarcomere and pull the thin filaments toward the center of the sarcomere.

Which of the following is not a type of muscle tissue? (IMPORTANT) Nonstriated Cardiac Skeletal Smooth

Nonstriated

What is a motor unit? (IMPORTANT)

One motor neuron and all the muscle fibers it innervates

Which of the following describes an I band sarcomere? (IMPORTANT)

Region of thin filaments only; part of two adjacent sarcomeres

Which skeletal muscle fibers are extremely resistant to fatigue, as long as enough oxygen is present, and deliver prolonged contractions?

Slow oxidative fibers (SO)

Which skeletal muscle fibers are relatively thin, and are red due to their abundant myoglobin content?

Slow oxidative fibers (SO)

Which of the following describes titin sarcomere?

Springy molecule that resists overstretching

Nerve-generated impulses in the sarcolemma are conducted by deep invaginations of the sarcolemma that run between each pair of terminal cisternae. These deep invaginations are called __________. (IMPORTANT)

T tubules

Which one of the following describes the H zone sarcomere? (IMPORTANT)

The central portion of an A band, where no thin filaments reach

Which of the following describes an M line sarcomere? (IMPORTANT)

The central portion of the H zone that contains tiny rods that hold the thick filaments together

Which of the following describes a sarcomere? (IMPORTANT)

The contractile unit, composed of myofilaments

Which of the following describes the functional characteristic of muscle called contractility?

When muscle cells shorten, they generate a strong pulling force.

insertion (IMPORTANT)

The point of attachment on the more movable bone in the illustration is called the _________ of the muscle.

Which of the following describes myofilament? (IMPORTANT)

There are two types of this structure, thick and thin, which slide against each other to cause muscle shortening.

Which of the following describes the events that occur during a muscle contraction of H zones? (IMPORTANT)

These structures disappear completely.

Which of the following describes the events that occur during a muscle contraction of Z discs? (IMPORTANT)

These structures move closer together, causing the sarcomere to shorten.

Which of the following describes the events that occur during a muscle contraction of I bands? (IMPORTANT)

These structures shorten as the muscle contracts.

Which of the following describes the events that occur during a muscle contraction of A bands? (IMPORTANT)

These structures stay the same length.

Which protein is a springlike molecule in sarcomeres that prevents overstretching, extending in a sarcomere from the Z disc to a filament and running within the filament to attach to the M line? (IMPORTANT)

Titin

C (IMPORTANT)

Which labeled structure in the given image is a fascicle?

d. storage of fat for a ready energy source for active muscles (IMPORTANT)

Which of the following statements is NOT an important function of the connective tissue sheaths contained within skeletal muscle? a. transmit contractile forces from the muscle fibers to the skeletal system b. provide a passageway for blood vessels and nerves c. bind muscle fibers together and contribute to elasticity of muscle d. storage of fat for a ready energy source for active muscles

During contraction, which of the following occur(s) in a sarcomere? (IMPORTANT)

Z discs move closer together and the lengths of the I bands and the H zone decrease.

One motor neuron and all the muscle fibers it innervates is __________. (IMPORTANT)

a motor unit

How does the sliding filament mechanism result in concentric contraction of skeletal muscle? (IMPORTANT) a. Myosin heads of thick filaments attach to thin filaments at both ends of a sarcomere and pull the thin filaments toward the center of the sarcomere. b. Acetylcholine diffuses out of vesicles at axon terminals and causes the concentric contraction to occur. c. Thin filaments attach to the myosin heads of thick filaments at the middle of a sarcomere and pull the thick filaments toward the center of the sarcomere. d. Titin, a spring-like molecule that extends the length of the thick filaments, pulls the myofibrils toward the center of a sarcomere. e. Norepinephrine diffuses out of vesicles at axon terminals and causes the concentric contraction to occur.

a. Myosin heads of thick filaments attach to thin filaments at both ends of a sarcomere and pull the thin filaments toward the center of the sarcomere.

What is the primary reason that men have greater muscle mass than women? a. The effects of androgen hormones give men greater muscle mass than women. b. Men are less affected by aging than women. c. Men take more anabolic steroids than women. d. Men are larger than women, so their percent muscle mass is greater.

a. The effects of androgen hormones give men greater muscle mass than women.

Titin is a protein that does all of the following except ____________.

aid in diffusion of acetylcholine across the synaptic cleft

Excitability is the special functional feature of muscle tissue that __________. (IMPORTANT)

allows electrical impulses to travel along the cells' sarcolemma, leading to contraction

Endomysium, perimysium, and epimysium __________. (IMPORTANT)

are each continuous with tendons and are the connective tissue sheaths around skeletal muscle fibers, muscle fascicles, and whole muscles, respectively

Slow oxidative muscle fibers ____________.

are prevalent in postural muscles of the back, and have abundant myoglobin and numerous mitochondria

Muscles may change due to exercise in all the following ways, except ____________. by increasing in diameter through satellite cells fusing with muscle fibers, contributing additional nuclei by increasing the production of contractile proteins by the conversion of fast glycolytic fibers to fast oxidative fibers, particularly through resistance training by increasing in number through dividing mitotically

by increasing in number through dividing mitotically

As Abe continued his fitness regimen, he started to think more about his muscle anatomy. He wondered how he was able to adjust the force generated by his muscles when he lifted different weights. His anatomy instructor explained motor units to him. Which of the following best explains how motor units are involved in controlling force exerted by a muscle? a. Each skeletal muscle fiber is innervated by a single motor neuron, so there are as many motor neurons as fibers within a single muscle. When more force is needed, additional motor neurons will be activated, and their individual fibers will contract. b. A motor unit is composed of all the muscle fibers within a single fascicle. Additional fascicles will be activated when more force is needed. c. A single motor neuron innervates a specific set of muscle fibers within each muscle. When more force is needed, more motor units are activated, which stimulates more muscle fibers to contract. d. Each muscle has one motor neuron that can selectively activate as many fibers as are needed. When trying to lift heavier objects, a single motor neuron will just stimulate more fibers to contract.

c. A single motor neuron innervates a specific set of muscle fibers within each muscle. When more force is needed, more motor units are activated, which stimulates more muscle fibers to contract.

During contraction, which of the following occurs in a sarcomere? (IMPORTANT) a. Z discs move farther apart. b. Thick filaments slide across each other to make titin more "springy." c. The lengths of the I bands and the H zone decrease. d. The thick and thin filaments get shorter. e. The A band gets longer.

c. The lengths of the I bands and the H zone decrease.

If you could not see the H zone in a photomicrograph of a sarcomere in skeletal muscle, ______. (IMPORTANT) a. the person from whom the sample was taken has muscular dystrophy b. you are looking at slow oxidative fibers c. the sarcomere is fully contracted d. titin, the springlike molecule has become paralyzed due to lack of ATP

c. the sarcomere is fully contracted

Myofilaments __________. (IMPORTANT) a. are responsible for shortening muscle cells b. are specific types of microfilaments c. include actin and myosin d. All are correct.

d. All are correct.

Which of the following is a similarity among skeletal, cardiac, and smooth muscles? (IMPORTANT) a. The cells of all three are striated. b. Their tissues are not under voluntary control. c. Their tissues contract as a sheet. d. All three depend on myofilaments for contraction. e. Their plasma membranes are called endomysium.

d. All three depend on myofilaments for contraction.

In __________ attachments, the strands of connective tissue are so short that the muscle fascicles appear to attach to the bone. (IMPORTANT)

direct

During contraction of a sarcomere, what happens to the A band? (IMPORTANT) a. The pull of actin filaments causes it to lengthen. b. It disappears. c. The A bands overlap, due to the pull of the thin filaments on the thick filaments. d. It shortens, because the myosin myofibrils (thick filaments) shorten. e. None is correct.

e. None is correct.

After being stretched, muscle tissue can recoil passively and resume its resting length. This is known as __________. (IMPORTANT)

elasticity

The property of skeletal muscle function that allows recoil after being stretched is ______. (IMPORTANT)

elasticity

An "overcoat" of dense, irregular connective tissue surrounding the whole skeletal muscle, and sometimes blending with the deep fascia, is known as __________. (IMPORTANT)

epimysium

The functional characteristic of muscles that allows electrical impulses to travel along the cells' sarcolemma, leading to contraction, is __________. (IMPORTANT)

excitability

In muscle tissue, the characteristic that is defined as "the ability to be stretched by contraction of an antagonist (opposing muscle)" is known as __________. (IMPORTANT)

extensibility

Slow oxidative fibers __________.

have thin fibers, numerous mitochondria, and abundant myoglobin

During an exercise where muscles do not shorten, ____ contractions have occurred.

isometric

Another name for muscle cells is __________. (IMPORTANT)

muscle fibers

The two proteins directly involved in muscle contraction are broadly called _____. (IMPORTANT)

myofilaments

The point at which a nerve ending and skeletal fiber meet is called a(n) ______. (IMPORTANT)

neuromuscular junction

In general, each skeletal muscle is supplied by __________.

one nerve, one artery, and one or more veins

The attachment of a muscle on the less movable bone is called the muscle's __________ (IMPORTANT)

origin

In muscle fibers, fascicles are surrounded by a layer of fibrous connective tissue called. (IMPORTANT)

perimysium

Myofilaments are ____________. (IMPORTANT)

protein filaments that are responsible for shortening muscle cells

The cell membrane of a muscle fiber is the ______. (IMPORTANT)

sarcolemma

The plasma membrane of a muscle cell is called the __________. (IMPORTANT)

sarcolemma

Z discs (Z lines) are ______. (IMPORTANT)

the boundaries of two adjacent sarcomeres

In a sarcomere, the I band is ____________. (IMPORTANT)

the region containing only thin filaments

The complex of a T tubule flanked by two terminal cisternae at each A-I junction is called a __________. (IMPORTANT)

triad

What is the term that collectively refers to both smooth and cardiac muscle? (IMPORTANT)

visceral