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

All three depend on myofilaments for contraction.

Their plasma membrane is called a sarcolemma.

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


Endomysium, perimysium, and epimysium ______.

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

Why are skeletal muscle fibers (skeletal muscle cells) multinucleate?

Skeletal muscle fibers are formed by the fusion of embryonic myoblasts.

__________ contraction occurs when a muscle generates force as it lengthens.


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


The connective tissue just external to the sarcolemma of a skeletal muscle fiber is __________.


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

It remains the same length.

In a sarcomere, the I band is ______.

the region containing only thin filaments.

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

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

__________ molecules in a sarcomere extend from the Z disc to the thick filament and run within the thick filament to the M line.


__________ is a condition in which myoglobin pours from crushed muscle tissue into the blood stream, clogging the filtering mechanisms of the kidneys and eventually leading to heart failure.


__________ are specialized contractile organelles found in muscle cells, which occupy most of the cell volume


__________ is a loss of muscle mass and decrease in muscle strength that may occur with advancing age.


The sliding filament mechanism is initiated by the release of __________ ions from the sarcoplasmic reticulum and the binding of those ions to the thin filaments


I band

Region of thin filaments only; part of two adjacent sarcomeres.

A band

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

Z disc

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

H zone

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

M line

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


Springy molecule that resists overstretching.

Slow oxidative muscle fibers ______.

have abundant myoglobin and numerous mitochondria.

are prevalent in postural muscles of the back.

What is a motor unit?

One motor neuron and all the muscle fibers it innervates.

T tubules ______.

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

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

aiding in diffusion of acetylcholine across the synaptic cleft.

Myofilaments are ______.

specific types of microfilaments that are responsible for shortening muscle cells.

Use anaerobic pathways to make ATP; tire quickly and are very powerful.

Fast glycolytic fibers

Are intermediate in many respects; more powerful than slow oxidative fibers.

Fast oxidative fibers

Have thin fibers, numerous mitochondria, and abundant myoglobin.

Slow oxidative fibers

__________ breaks down acetylcholine after it signals a contraction.

Acetylcholinesterase (AchE)

The chronic-pain condition that includes musculoskeletal pain, fatigue, sleep abnormalities, and headaches is __________.


The attachment of a muscle on the more movable bone is called the muscle's __________


Greater muscle mass in males is mostly due to __________.


__________ cells proliferate after injury to a skeletal muscle and produce proteins to repair the injury.


During contraction, which of the following occur in a sarcomere? Choose the two correct answers.

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

__________ is a sex-linked recessive disease, expressed almost exclusively in males, and usually diagnosed when a child is between 2 and 10 years old

Duchenne Muscular Dystrophy

Muscles may change due to exercise in all the following ways, except ______.

by increasing in number through dividing mitotically

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