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The ability of a muscle to be stimulated is called


Action potential frequency is best described as:

The number of action potentials produced per unit of time.

Active tension in a muscle is defined as

the tension applied to a load when the muscle contracts.

All of the following are true of muscle tone except

depends on multiple motor units contracting in phase with each other

The "all-or-none" concept of skeletal muscle contraction means that

Muscle fibers contract completely.

Binding of acetylcholine with its receptor on muscle cells causes

opening of a ligand-gated sodium channel

A buildup of acetylcholine in the synaptic cleft without breakdown may cause . . .

spastic paralysis

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


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


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


The cytoplasm within the muscle fiber is known as the


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?

The calcium removes the tropomyosin block

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


Eccentric muscle contractions occur when

a person slowly lowers a heavy weight

An effect of aging on skeletal muscle is increased time for muscle to respond to stimuli, increased recovery time, loss of muscle fibers. What is not an effect of aging on skeletal muscle?

increased myoglobin

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


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


Explain why treppe takes place in muscle contractions?

increased calcium levels around the myofibrils

The functional connection between a nerve fiber and a muscle fiber is called a(an)


In a muscle twitch, what represents the time between application of a stimulus and the beginning of contraction?


Intercalated discs are capable of doing what?

pass electrical stimulation to other cardiac cells

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

It deactivates acetylcholine.

In the myofibril, ATP is used for . . .

Muscle tone, muscle contraction, muscle relaxation

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


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


Muscle fibers and neurons are called electrically excitable cells because

their plasma membranes exhibit voltage changes in response to stimulation

Muscle fibers are bundled into groups known as


Muscle soreness can be produced by . . .

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

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


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

skeletal muscle

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?


One of the characteristics of muscle tissue is that is has conductivity. Which of the following best describes this characteristic?

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

One of the characteristics of muscle tissue is that is has excitability. Which of the following best describes this characteristic?

Muscles contract when stimulated.

One of the characteristics of muscle tissue is that is has extensibility. Which of the following best describes this characteristic?

Muscles can stretch when needed

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 outer membrane of the muscle fiber is known as the


A person with an arm immobilized in a cast for 6 weeks will

develop muscular atrophy.

The properties of cardiac muscle cells are intercalated discs, involuntary, branching fibers. What is not a property?

shorter in duration of contraction than skeletal muscles.

Rapid contraction, break down ATP rapidly, fewer mitochondria than slow-twitch fibers are all true about fast-twitch fibers, which in not true?

high amount of myoglobin

The recovery stroke in muscle contraction involves what?

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

Slow contraction, good blood supply, and many mitochondria are characteristics of slow-twitch fibers, what is not a characteristic?

large diameter.

Smooth body movements result from

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

The striations in striated muscle correspond with actual molecular structures. Which of the following is the H band?

a band where only myosin molecules are found

The striations in striated muscle correspond with actual molecular structures. Which of the following is the I band?

a band where only actin molecules are found

The striations in striated muscle correspond with actual molecular structures. Which of the following is the Z line?

an attachment point for actin molecules

The sum of active and passive tension is called

total tension.

Thick filaments within the myofibril are composed of


Thin filaments within the myofibril are composed primarily of


The tissues of cardiac muscle have unique structures known as

intercalated discs

The tissue surrounding an entire muscle is known as


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


Triads in skeletal muscle consist of what

two terminal cisternae and a T-tubule.

Unitary smooth muscle is found in what location of the body?

Digestive tract, reproductive tract, urinary tract.

What are the most common neurotransmitters in smooth muscle?

acetylcholine and norepinephrine

What assures quick removal of neurotransmitter at the junction between a nerve and a muscle?


What best describes a muscle motor unit?

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

What best describes the use of muscle tone in the body?

It keeps our backs straight and our heads up

What determines the height of the peaks in multiple motor unit summation?

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

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


What is a molecule that binds to a receptor?


What is considered to be parts of the series-elastic components of muscle?

Endomysium, perimysium, epimysium, fascia, and tendons.

What is one of the primary functions of muscle tissue?

heat production

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

-70 mv

What is true about distribution of fast and slow-twitch fibers in the body?

Slow-twitch fibers are usually more resistant to fatigue

What is true about skeletal muscle fibers in aging people?

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.

What is unique about cardiac muscle tissue?

The cells have large mitochondria

What kind of molecule is ACh?


What part of a muscle is the muscle fiber?

muscle cell itself

What represents extreme muscular fatigue when the muscle is incapable of either contracting or relaxing?

physiological contracture

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


What type of molecule is acetylcholine?

It is a neurotransmitter.

What would represent incomplete tetanus?

multiple contractions with slight relaxation

When acetylcholine is broken down by acetylcholinesterase in the synaptic cleft, what happens to the choline?

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

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

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


When the thick and the thin filaments pull together, which of the following is TRUE?

The sarcomere gets shorter.

Which effects of exercise elevate the body temperature?

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

Which energy storage source is most commonly used during the first 10 seconds of exercise?

creatine phosphate

Which is true about smooth muscle?

The resting membrane potential is less negative than in skeletal muscle

Which is true of an isometric muscle contraction?

The amount of tension increases during the contraction

Which muscle type does NOT have striations?


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


Which muscle type is usually voluntary?


Which muscle types has only one nucleus?


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

Myosin, actin, and elastic (titin) filament.

Which of the following best describes the function of the series-elastic component of muscle?

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

Which of the following is the A band within a myofibril?

myosin myofilaments in profile

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


Which of the following is TRUE of cardiac tissue?

It has abundant glycogen and myoglobin and is aerobic

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


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


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


Which protein attaches Z discs to myosin myofilaments?


Which represents the amount of oxygen that is necessary for the body to recover from anaerobic respiration?

oxygen debt

Which tissues have the greatest ability to repair itself?

Smooth muscle

Which type of muscle fatigue represents depletion of ATP?


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