Binding of calcium to calmodulin is a step in excitation-contraction coupling of ________ cells.

smooth muscle

Which type of muscle CANNOT contract without being stimulated by the nervous system?

skeletal

Muscle tissue has all of the following properties except ________.

secretion

Once a motor neuron has fired, all the muscle fibers in a muscle contract.

False

What structure in skeletal muscle cells functions in calcium storage?

sarcoplasmic reticulum

Myoglobin ________.

stores oxygen in muscle cells

In which phase of the muscle twitch shown in the above figure would the maximum amount of ATP be consumed by myosin head groups?

B

The connective tissue that covers structure A is continuous with which of the following?

tendon

Which of the following surrounds the individual muscle cell?

endomysium

The major role of the sarcoplasmic reticulum is to regulate ________.

intracellular levels of Ca²⁺

When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods?

refractory period

What produces the striations of a skeletal muscle cell?

the arrangement of myofilaments

In an isotonic contraction, the muscle ________.

changes in length and moves the "load"

The contractile units of skeletal muscles are ________.

myofibrils

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 ______.

recruitment

What is the functional unit of a skeletal muscle called?

a sarcomere

Which lettered protein functions as a motor protein?

C

During muscle contraction, myosin cross bridges attach to which active sites?

actin filaments

Most skeletal muscles contain ________.

a mixture of fiber types

The smallest contractile unit of a muscle fiber is ________.

the sarcomere

The protein troponin is shown in this figure to be bound to which substance?

calcium ion

Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments.

True

Which of the following describes the neurons shown in this figure?

somatic motor neurons

What is the functional role of the T tubules?

enhance cellular communication during muscle contraction

A muscle that is lengthening while it produces tension is performing a(an) ________ contraction.

eccentric

A contraction in which the muscle does not shorten but its tension increases is called isometric contraction.

True

Choose the FALSE statement.

Skeletal muscle cells use creatine phosphate instead of ATP to do work.

The major function of the sarcoplasmic reticulum in muscle contraction is to ________.

regulate intracellular calcium concentration

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers?

a long, relaxing swim

What cellular event is indicated by A?

exocytosis

During isometric contraction, the energy used appears as movement.

False

Isometric contraction leads to movement of a load.

False

Which of the following is CORRECTLY paired?

skeletal muscle: voluntary control

The distance between Z discs ________ during muscle contraction.

decreases

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

diffusion of Ca²⁺ into the axonal terminus

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction

acetylcholinesterase destroying the ACh

Which statement accurately describes the event indicated by B?

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

Which of the following is the smallest structural unit in which the distinctive striated bands characteristic of skeletal muscle are observed?

D

The response of a motor unit to a single action potential of its motor neuron is called ________.

a muscle twitch

The force of muscle contraction is controlled by multiple motor unit summation or recruitment.

True

How many motor units are illustrated in the figure?

2

Which muscle cells have the greatest ability to regenerate?

Smooth

An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops.

True

The connective tissue sheaths of skeletal muscle, in order from internal to external, are the ________.

endomysium, perimysium, and epimysium

Smooth muscles are able to regenerate throughout life.

True

What is a cross bridge cycle?

It is the cycle in which an energized myosin head binds to actin and performs a power stroke, then binds to ATP in order to detach and re-energize.