chapter 9 anatomy

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

Most skeletal muscles contain ________.

a mixture of fiber types

What is the functional unit of a skeletal muscle called?

a sarcomere

The term aponeurosis refers to

a sheetlike indirect attachment to a skeletal element

Connective tissue covering the exterior of a muscle organ.

A

Z disc

A

The giant protein titin maintains the organization of the ________ assisting in muscle stretching.

A band

Connective tissue sheath surrounding individual muscle fibers

B

H zone

B

Muscle tone is _____

a state of sustained partial contraction

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

acetylcholinesterase destroying the ACh

The sliding filament model of contraction involves _______

actin and myosin sliding past each other and partially overlapping

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

actin filaments

Which of the following is not a role of ionic calcium in muscle contraction?

activates epinephrine released from adrenal gland

Which of the following is not a connective tissue sheath that wraps individual muscle fibers?

aponeurosis

What is the role of calcium ions in muscle contraction?

bind to regulatory sites on troponin to remove contraction inhibition

In an isotonic contraction, the muscle _____

changes in length and moves the "load"

Which of the following is the correct sequence of events for muscle contractions?

motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

Which of the following would be recruited later in muscle stimulation when contractile strength increases?

motor units with larger, less excitable neurons

Of the following muscle types, which has only one nucleus, no sarcomeres, and rare gap junctions?

multiunit smooth muscle

The contractile units of skeletal muscles are ____

myofibrils

The oxygen-binding protein found in muscle cells is ____

myoglobin

Rigor mortis occurs because ________.

no ATP is available to release attached actin and myosin molecules

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped,

no muscle tension could be generated

What is the primary function of wave summation?

produce smooth, continuous muscle contraction

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

refractory period

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

regulate intracellular calcium concentration

The muscle cell membrane is called the ______

sarcolemma

What structure in skeletal muscle cells functions in calcium storage?

sarcoplasmic reticulum

Muscle tissue has all of the following properties except ________.

secretion

Which muscle cells have the greatest ability to regenerate?

smooth

Myoglobin ________.

stores oxygen in muscle cells

Creatine phosphate functions in the muscle cell by _______

storing energy that will be transferred to ADP to resynthesize ATP

Which of the following is not a component of the standard treatment for muscle strain?

stretching of the muscle

What is the most distinguishing characteristic of muscle tissue?

the ability to transform chemical energy into mechanical energy

What produces the striations of a skeletal muscle cell?

the arrangement of myofilaments

What does excess postexercise oxygen consumption represent?

the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used

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

the site of calcium regulation differs

Smooth muscle is characterized by all of the following except ____

there are more thick filaments than thin filaments

Which of the following statements is most accurate?

Muscle tension remains relatively constant during isotonic contraction.

A relatively high percentage are found in successful marathon runners

Slow (oxidative), fatigue-resistant fibers

Abundant in muscles used to maintain posture

Slow (oxidative), fatigue-resistant fibers

Depends on oxygen delivery and aerobic mechanisms

Slow (oxidative), fatigue-resistant fibers

Red fibers, the smallest of the fiber types

Slow (oxidative), fatigue-resistant fibers

Which of the following statements is true?

Striated muscle cells are long and cylindrical with many nuclei

What part of the sarcolemma contains acetylcholine receptors?

motor end plate

I band

C

Individual muscle fiber

C

Excitation-contraction coupling requires which of the following substances?

Ca2+ and ATP

Which of the following statements is false or incorrect?

Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP.

Which of the following is true about smooth muscle?

Certain smooth muscle cells can actually divide to increase their numbers

A band

D

Bundle of muscle cells surrounded by a perimysium

D

Connective tissue surrounding muscle fiber bundles

E

M line

E

Contain abundant amounts of glycogen

Fast (oxidative or glycolytic), fatigable fibers

Have very fast-acting myosin ATPases and depend upon anaerobic metabolism during contraction

Fast (oxidative or glycolytic), fatigable fibers

Which of the following describes the cells of unitary smooth muscle?

They exhibit spontaneous action potentials.

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

Which of the following surrounds the individual muscle cell?

endomysium

What is the functional role of the T tubules?

enhance cellular communication during muscle contraction

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is _______

glycolysis

Which of the choices below does not describe how excess postexercise oxygen consumption (oxygen deficit) restores metabolic conditions?

increases the level of lactic acid in the muscle

The strongest muscle contractions are normally achieved by _______

increasing the stimulation up to the maximal stimulus

Fatigued muscle cells that recover rapidly are the products of

intense exercise of short duration

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

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors.

latent

Which of the following is a factor that affects the velocity and duration of muscle contraction?

load on the fiber