CH 7-10 Test Bank

Muscle cells

can only contract

Which of the following is characteristic of cardiac muscle?

cardiac muscle cells are striated

The term used to describe muscular growth in response to usage is

hypertrophy

A muscle producing almost peak tension during rapid cycles of contraction and relaxation is said to be in

incomplete tetanus

Most neurons in the brain are

multipolar

Exhaustion of energy reserves or decline in pH due to production and dissociation of lacticc acid causes

muscle fatigue

Which statement regarding the relaxation phase of a muscle twitch is true?

muscle tension falls to resting levels

The additional oxygen required during the recovery period to restore the normal pre-exertion levels is called the

oxygen debt

A traid is a

pair of terminal cisternae of the SR with a T tubule between them

All of the nervous tissue outside of the CNS comprises the

peripheral nervous system

Which property of the sarcolemma is affected by the neurotransmitter ACh?

permeability

The terminal cisternae are structural features of the

sarcoplasmic reticula

The skeletal muscles store calcium ions in the terminal cisternae of the

sarcoplasmic reticulum

Which of the following is a function of the efferent division of the nervous system?

sending signals to muscles

Which of the following statements describes how muscles help maintain homeostasis?

skeletal muscle contractions help maintain body temperature

Which statement regarding skeletal muscle is true?

skeletal muscles contain blood vessels

Nonstriated, involuntary muscle is

smooth

The suddent rush of which ion into the sarcoplasm produces an action potential in the sarcolemma?

sodium

As a skeletal muscle contraction is initiated, ACh binding alters the motor end plate membrane's permeability to

sodium ions

Creatine phosphate serves to

supply energy to synthesize ATP

The heart has to be able to regulate its contractions. Heart muscle, unlike skeletal muscle, cannot go into a tetanus. This is because

the heart muscle has to be able to consistently contract and pump blood in a controlled fashion

During a skeletal muscle contraction, calcium binds to which molecule?

troponin

Smooth muscle

uses primarily aerobic metabolism

The enzyme acetylcholinesterase causes ACh to

break down

During activities requiring anaerobic endurance

most of the muscle's energy is produced in mitochondria

The specialzied sarcolemma that contains ACh receptors is the ___

motor end plate

Neurotransmitters that cause skeletal muscle contraction are normally stored in:

motor neuron axon terminals

Which of the following helps maintain body position by tensing and firming a muscle even when the entire muscle is not contracting?

muscle tone

A sheath of connective tissue surrounding a bundle of striated muscle fibers is called

perimysium

The area between Z lines is the ___

sarcomere

The repeating functional unit of a myofibril is the

sarcomere

Acetylcholinesterase is found within the

synaptic cleft

Which of the following is one of the steps that ends a contraction?

ACh is broken down by acetylcholinesterase

Upon the nerve impulse arriving at the axon terminal

ACh is released

The stiffness that occurs at death, when actin and myosin molecules stay linked to each other in a contracted state, is due to a lack of

ATP

Which of the following statements describes the cause for the cessation of an action potential?

Acetylcholinesterase breaks down ACh

The brain and spinal cord comprise the

CNS

Which of the following structures is composed of proteins that connect the central portions of each thick filament to its neighbors?

M line

Which statement regarding "heat loss" is true?

Muscle contractions play an important role in the maintenance of normal body temperature

A resting muscle generates most of its ATP by

aerobic respiration

The ___ division of the nervous system brings sensory information to the central nervous

afferent

The part of the peripheral nervous system that brings information to the CNS is the

afferent division

A broad sheet formed by the collagen fibers of the connective tissues of skeletal muscle is called

an aponeurosis

Smooth muscle cells

are spindle-shaped

The glial cells responsible for maintaining blood-brain barrier are the

astrocytes

The largest and most numerous of the glial cells in the CNS are the

astrocytes

Which of the following phrases best describes the cyclical actions of a myosin cross-bridge during a muscle contraction?

attach, pivot, detach, and reactivate

The ___ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity.

autonomic

Which of the following structures controls individual muscle fibers?

axon (nerve fiber)

The _____ contains vesicles filled with ACh

axon terminal

The active sites on actin molecules are usually covered up by other molecules. What is the critical material required to uncover the active sites on the actin molecules that will then bind to myosin heads?

calcium

In response to action potentials arriving from the transverse tubules, the sarcoplasmic reticulum releases

calcium ions

During moderate activity, which of the following is true regarding muscle metabolism?

glucose and fatty acids are catabolized

Regarding muscle fiber elongation:

gravity may help lengthen a muscle fiber after elongation

Fast fibers

have high glycogen reserves

Skeletal muscle fibers differ from "typical cells" in that these muscle fibers

have many nuclei

Which of the following occurs when tension production rises to a peak and very brief periods of relaxation occur?

incomplete tetanus

"Anaerobic endurance"

is exemplified by contractions of fast muscle fibers

In general, the nervous system

is fast acting

Which of the following statements correctly defines tension?

it is a force to an object that tneds to pull the object toward the source of the force

Which of the following occurs when glycolysis produces pyruvate faster than it can be used by the mitochondria?

lactic acid is produced

Calcium ions are released from the sarcoplasmic reticulum during the ____ phase of contraction

latent

In which of the following phases of a twitch is no tension produced by the muscle fiber?

latent period

Regarding lactic acid regulation, which cells in the body consume extra oxygen and produce ATP for the conversion of excess lactate absorbed from the blood back to glucose?

liver cells

Small phagocytic glial cells, which are derived from white blood cells are called

microglia

Muscle fasicles are separated by

perimysium

Which of the following is true about red muscles?

red muscles are slower than white muscles

Which of the following is an accurate characterisitc of slow fibers?

resting slow muscle fibers contain oxygen reserves, bound to myoglobin

The amount of tension produced by an individual muscle fiber depends solely upon which of the following factors?

the number of pivoting cross-bridges

Regarding a skeletal muscle fiber, wherever a T-tubule encircles a myofibril, the tuble is tightly bound to:

the sarcoplasmic reticulum

Which statement regarding isometric contractions is true?

the tension produced never exceeds the load

How do skeletal muscle contractions cause movement of the bones?

they pull on tendons

Myosin molecules are found in which of the following structures?

thick filaments

What is the function of the transverse tubules?

to transmit electrical impulses to the cell's interior

Tropomyosin strands are held in position by which of the following?

troponin molecules

A single stimulus-contraction-relaxation sequence in a muscle fiber is known as a

twitch

Muscular System Functions

1. move the skeleton 2. maintain posture and body position 3. support soft tissues 4. guard entrances and exits 5. maintain body temperature

Each myofibril consists of approximately ____ sarcomeres

10,000

Place these steps of muscle contraction in the correct order: 1. action potential is generated along the sarcolemma 2. nerve impulse arrives at synapse 3. calcium is released into muscle cell cytoplasm 4. ACh is produced 5. actin and myosin molecules continuously cross-link, with actin molecules being pulled inward

2, 4, 1, 3, 5

Choose the correct statement regarding motor units

a motor neuron may control only two or three muscle fibers of the eye muscles

Myofibrils are made primarily of

actin and myosin

Glycolysis

is an anaerobic process

The region of a sarcomere containing myosin, going from one end of the mysoin molecules to the other end of the myosin molecules, is the

A band

The thick filaments of sarcomeres are contained in which band?

A band

Which of the following structures is composed of a layer of collagen fibers that separates a muscle from surrounding tissues and organs?

Epimysium

The area of the sarcomere that is the light region between two successive A-bands is the

I band

The striated appearance of skeletal muscle results from

actin and myosin arrangement

During which phase is the stimulus frequency so high that the relaxation phase is eliminated?

complete tetanus

Which of the following terms defines a force that tends to push an object away from the source of the applied force?

compression

The branching structures that, together with the cell body, are sensitive to chemical, mechanical, or electrical stimulation are called

dendrites

Which of the following structures surrounds each skeletal muscle fiber and ties adjacent muscle fibers together?

endomysium

A layer of collagen fibers that surround an entire muscle is called:

epimysium

A bundle of muscle fibers is a

fascicle

A muscle ____ contains a sarcolemma, sarcoplasm, myofilaments, and myofibrils.

fiber

Which of the following parts of a neuromuscular junction is a specialized portion of the sarcolemma that contains receptors for ACh?

motor end plate

Why do individual muscle twitches have to be added together, as in summation or tetanus?

multiple twitches add up to an increase in muscle fiber tension, which increases the strength of the muscle

Which of the following occurs as a result of motor units in a particular muscle being always active, even though their contractions do not produce enough movement to cause contraction?

muscle tone

The myelin sheaths that surround the axon of some of the neurons in the CNS are formed by

oligodendrocytes

Which of the following structures is a specialized form of smooth endoplasmic reticulum that forms a tubular network around each myofibril?

sarcoplasmic reticulum

A person whose genetic makeup makes him or her a better marathon runner than a sprinter probably has more _____ in his or her leg muscles

slow fibers