Chapter 9 A&P Flashcards

Muscle contraction will always promote movement of body parts regardless of how they are attached.

A. T
B. F

Muscle tissue has all of the following properties except ________.

A.extensibility
B.contractility
C.excitability
D.secretion

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

A.skeletal
B.smooth
C.visceral
D.cardiac

Which muscle characteristic describes the ability of muscle to respond to a stimulus?

extensibility
elasticity
contractility
excitability

Which of the following is CORRECTLY paired?

skeletal muscle: voluntary control
smooth muscle: striated
cardiac muscle: nonstriated
cardiac muscle: voluntary control

Muscle tissue does NOT ________.

produce blood cells
produce movement
generate heat
stabilize joints
maintain posture

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

True
False

Muscle cells store more creatine phosphate than ATP resulting in the muscle having a reserve source of energy.

True
False

Cells of unitary smooth muscle are found in the longitudinal and circular muscle layers of the intestine.

True
False

Cardiac muscle has a limited regenerative capacity.

True
False

What is the role of tropomyosin in skeletal muscles?
A. Tropomyosin is the receptor for the motor neuron neurotransmitter.
B. Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.
C. Tropomyosin is the chemical that activates the myosin heads.
D. Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules.

What does excess postexercise oxygen consumption represent?

A. the amount of oxygen taken into the body immediately after the exertion
B. amount of oxygen needed for aerobic activity to accomplish the same amount of work
C. the amount of oxygen equal to the oxygen already used
D. the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used

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.

refractory
contraction
relaxation
latent

What is the primary function of wave summation?

produce smooth, continuous muscle contraction
prevent muscle fatigue
increase muscle tension
prevent muscle relaxation

Rigor mortis occurs because ________.

A. no ATP is available to release attached actin and myosin molecules
B. sodium ions leak into the muscle causing continued contractions
C. the cells are dead
D. proteins are beginning to break down, thus preventing a flow of calcium ions

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

A. resynthesizes creatine phosphate and ATP in muscle fibers
B. converts lactic acid back into glycogen stores in the liver
C. increases the level of lactic acid in the muscle
D. replaces the oxygen removed from myoglobin

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

elevation of the limb
ice on the muscle
rest of the muscle
stretching of the muscle

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

aponeurosis
endomysium
perimysium
epimysium

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

triggers neurotransmitter secretion

binds with troponin

removes contraction inhibitor

activates epinephrine released from adrenal gland

The sliding filament model of contraction involves ________.

A.actin and myosin lengthening in order to slide past each other

B.actin and myosin sliding past each other and partially overlapping

C.the Z discs sliding over the myofilaments

D.the shortening of thick filaments so that thin filaments slide past

What is the most distinguishing characteristic of muscle tissue?

the design of the fibers

the ability to respond to nervous stimulation

the diversity of activity of muscle tissue

the ability to transform chemical energy into mechanical energy

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?

gym climbing
playing baseball or basketball
a sprint by an Olympic runner
a long, relaxing swim

In the muscles of the limbs, the origin usually lies proximal to the insertion.

True
False

What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated?

A. A skeletal muscle fiber is innervated by multiple motor neurons.
B. Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron.
C. Motor neurons always innervate thousands of skeletal muscle fibers.
D. A motor neuron typically innervates only one skeletal muscle fiber.

Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers?

Action potentials.
Acetylcholine.
Sodium ions.
Calcium ions.

What is name given to the regularly spaced infoldings of the sarcolemma?

motor endplates
sarcoplasmic reticulum
transverse or T tubules
terminal cisternae

A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected?

Voltage-gated sodium channels.

Potassium leak channels.

A series of proteins that control calcium release.

Myosin cross-bridge binding sites.

Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction?

Sodium release from the sarcoplasmic reticulum initiates the contraction.

Action potentials propagate into the interior of the skeletal muscle fiber.

Calcium release from the sarcoplasmic reticulum initiates the contraction.

Voltage-sensitive proteins change shape.

Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process?

Excitation refers to the propagation of action potentials along the axon of a motor neuron.

Excitation refers to the shape change that occurs in voltage-sensitive proteins in the sarcolemma.

Excitation, in this case, refers to the propagation of action potentials along the sarcolemma.

Excitation refers to the release of calcium ions from the sarcoplasmic reticulum.

In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter?

dopamine
serotonin
acetylcholine (ACh)
norepinephrine

When an action potential arrives at the axon terminal of a motor neuron, which ion channels open?

voltage-gated sodium channels
voltage-gated potassium channels
chemically gated calcium channels
voltage-gated calcium channels

What means of membrane transport is used to release the neurotransmitter into the synaptic cleft?

a channel
exocytosis
a protein carrier

The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur?

Binding causes potassium voltage-gated channels to open in the motor endplate.

Binding causes chemically gated potassium channels to open in the motor end plate.

Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate.

Binding causes voltage-gated sodium channels to open in the motor endplate.

How is acetylcholine (ACh) removed from the synaptic cleft?

diffusion away from the synaptic cleft
a reuptake pump on the axon terminal
acetylcholinesterase (AChE; an enzyme)

The action potential on the muscle cell leads to contraction due to the release of calcium ions. Where are calcium ions stored in the muscle cell?

cytosol
sarcolemma
terminal cisternae of the sarcoplasmic reticulum
T tubule

What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell?

arrival of an action potential
calcium ion pump
ATP
troponin

The binding of calcium to which molecule causes the myosin binding sites to be exposed?

actin
troponin
tropomyosin

A myosin head binds to which molecule to form a cross bridge?

troponin
tropomyosin
actin

What causes the myosin head to disconnect from actin?

binding of calcium
binding of ATP
binding of troponin
hydrolysis of ATP

What energizes the power stroke?

binding of ATP
calcium
hydrolysis of ATP

The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge?

Calcium bound to troponin
A myosin head bound to actin
Troponin bound to tropomyosin
ATP bound to a myosin head

What structure is the functional unit of contraction in a skeletal muscle fiber?

The sarcomere
The cross bridge
The triad
The junctional folds of the sarcolemma

Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?

Calcium ions are stored in the sarcoplasmic reticulum.

Calcium ions are stored in the mitochondria.

Calcium ions are stored in the nuclei.

Calcium ions are stored in the transverse tubules.

After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?

ATP binds to the myosin head.

Calcium ions bind to troponin.

ADP and inorganic phosphate are bound to the myosin head.

Acetylcholine binds to receptors in the junctional folds of the sarcolemma.

How does the myosin head obtain the energy required for activation?

The energy comes from the hydrolysis of GTP.

The energy comes from oxidative phophorylation.

The energy comes from the direct phosphorylation of ADP by creatine phosphate.

The energy comes from the hydrolysis of ATP.

What specific event triggers the uncovering of the myosin binding site on actin?

Calcium ions bind to tropomyosin and change its shape.

Sodium ions bind to troponin and change its shape.

Calcium ions bind to troponin and change its shape.

Calcium release channels open in the sarcoplasmic reticulum, and calcium levels rise in the sarcoplasm.

When does cross bridge cycling end?

Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.

Cross bridge cycling ends when calcium release channels in the sarcoplasmic reticulum open.

Cross bridge cycling ends when ATP binds to the myosin head.

Cross bridge cycling ends when calcium ions are passively transported back into the sarcoplasmic reticulum.

Action potential propagation in a skeletal muscle fiber ceases when acetylcholine is removed from the synaptic cleft. Which of the following mechanisms ensures a rapid and efficient removal of acetylcholine?

Acetylcholine is transported back into the axon terminal by a reuptake mechanism.

Acetylcholine is degraded by acetylcholinesterase.

Acetylcholine diffuses away from the cleft.

Acetylcholine is transported into the postsynaptic neuron by receptor-mediated endocytosis.

The neuromuscular junction is a well-studied example of a chemical synapse. Which of the following statements describes a critical event that occurs at the neuromuscular junction?

Acetylcholine binds to its receptor in the junctional folds of the sarcolemma. Its receptor is linked to a G protein.

Acetylcholine is released and moves across the synaptic cleft bound to a transport protein.

When the action potential reaches the end of the axon terminal, voltage-gated sodium channels open and sodium ions diffuse into the terminal.

Acetylcholine is released by axon terminals of the motor neuron.

Action potentials travel the length of the axons of motor neurons to the axon terminals. These motor neurons __________.

arise in the epimysium of a skeletal muscle and extend to individual skeletal muscle fibers

extend from the brain or spinal cord to the sarcolemma of a skeletal muscle fiber

extend from the spinal cord to the sarcolemma of a skeletal muscle fiber

extend from the brain to the sarcolemma of a skeletal muscle fiber

Calcium entry into the axon terminal triggers which of the following events?

Cation channels open and sodium ions enter the axon terminal while potassium ions exit the axon terminal.

Acetylcholine is released into the cleft by active transporters in the plasma membrane of the axon terminal.

Acetylcholine binds to its receptor.

Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine.

Acetylcholine binds to its receptor in the sarcolemma and triggers __________.

the opening of voltage-gated calcium channels
the opening of ligand-gated cation channels
the opening of calcium-release channels
the opening of ligand-gated anion channels

Sodium and potassium ions do not diffuse in equal numbers through ligand-gated cation channels. Why?

A. The outside surface of the sarcolemma is negatively charged compared to the inside surface. Sodium ions diffuse outward along favorable chemical and electrical gradients.
B. The inside surface of the sarcolemma is negatively charged compared to the outside surface. Potassium ions diffuse inward along favorable chemical and electrical gradients.
C. The outside surface of the sarcolemma is negatively charged compared to the inside surface. Potassium ions diffuse outward along favorable chemical and electrical gradients.
D. The inside surface of the sarcolemma is negatively charged compared to the outside surface. Sodium ions diffuse inward along favorable chemical and electrical gradients.

Myasthenia gravis is sometimes treated medically by a treatment that involves ________.

boosting the activity of the immune system

suppressing the release of acetylcholine from synaptic vesicles

suppressing the synthesis of acetylcholine

inhibiting the action of acetylcholinesterase

Cross bridge formation between myosin heads and actin molecules is caused by the elevation of calcium ion concentration in the cytosol. During rigor mortis, this elevation of calcium ion concentration in the cytosol is permanent because ________.

mitochondria stop producing ATP molecules required by the sarcoplasmic reticulum's calcium ion pumps

troponin molecules bind irreversibly to calcium ions to prevent them from being removed from the cytosol

tropomyosin molecules bind irreversibly to calcium ions to prevent them from being removed from the cytosol

acetylcholine continues to stimulate the release of calcium ions from the sarcoplasmic reticulum

In a bedridden patient recovering from a badly fractured femur, disuse atrophy in the thigh muscles is caused by _________.

decreased ability of muscle cells to produce ATP, resulting in decreased ability of the muscles to contract

decreased ability to synthesize acetylcholine in the neurons that innervate the thigh muscles

decreased synthesis of muscle proteins and/or increased breakdown of muscle proteins

none of the above

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

T
F

The thin filaments (actin) contain a polypeptide subunit G actin that bears active sites for myosin attachment.

T
F

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

T
F

Eccentric contractions are more forceful than concentric contractions.

T
F

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.

T
F

Peristalsis is characteristic of smooth muscle.

T
F

During isometric contraction, the energy used appears as movement.

T
F

One of the important functions of skeletal muscle contraction is production of heat.

T
F

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.

T
F

Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units.

T
F

A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.

T
F

The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.

T
F

When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length.

T
F

Most skeletal muscles contain ________.

a predominance of fast oxidative fibers
muscle fibers of the same type
a predominance of slow oxidative fibers
a mixture of fiber types

Fatigued muscle cells that recover rapidly are the products of ________.

intense exercise of short duration
intense exercise of long duration
slow exercise of short duration
slow exercise of long duration

The strongest muscle contractions are normally achieved by ________.

increasing stimulus above the threshold

recruiting small and medium muscle fibers

increasing the stimulation up to the maximal stimulus

increasing stimulus above the treppe stimulus

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

large motor units with small, highly excitable neurons

motor units with the longest muscle fibers

motor units with larger, less excitable neurons

many small motor units with the ability to stimulate other motor units

Excitation-contraction coupling directly requires which of the following substances?

Ca2+ and ATP
ATP only
Ca2+ only
ATP and glucose

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

load on the fiber
muscle length
size of the muscle fibers stimulated
number of muscle fibers stimulated

Myoglobin ________.

is a protein involved in the direct phosphorylation of ADP

produces the end plate potential

breaks down glycogen

stores oxygen in muscle cells

What structure in skeletal muscle cells functions in calcium storage?

mitochondria
myofibrillar network
intermediate filament network
sarcoplasmic reticulum

Creatine phosphate functions in the muscle cell by ________.

forming a temporary chemical compound with myosin

inducing a conformational change in the myofilaments

forming a chemical compound with actin

storing energy that will be transferred to ADP to resynthesize ATP

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

synthesize actin and myosin myofilaments

make and store phosphocreatine

provide a source of myosin for the contraction process

regulate intracellular calcium concentration

What produces the striations of a skeletal muscle cell?

the T tubules
a difference in the thickness of the sarcolemma
the sarcoplasmic reticulum
the arrangement of myofilaments

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

myosin filaments
Z discs
actin filaments
thick filaments

Which of the following surrounds the individual muscle cell?

epimysium
endomysium
perimysium
fascicle

The term aponeurosis refers to ________.

the tropomyosin-troponin complex

the bands of myofibrils

the rough endoplasmic reticulum

a sheetlike indirect attachment to a skeletal element

The oxygen-binding protein found in muscle cells is ________.

immunoglobin
hemoglobin
myoglobin
ATP

The contractile units of skeletal muscles are ________.

T tubules
myofibrils
microtubules
mitochondria

What is the functional unit of a skeletal muscle called?

a myofilament
a myofibril
a sarcomere
the sarcoplasmic reticulum

What is the functional role of the T tubules?

enhance cellular communication during muscle contraction

synthesize ATP to provide energy for muscle contraction

hold cross bridges in place in a resting muscle

stabilize the G and F actin

What is the role of calcium ions in muscle contraction?

reestablish glycogen stores

increase levels of myoglobin

form hydroxyapatite crystals

bind to regulatory sites on troponin to remove contraction inhibition

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 ________.

hydrochloric acid
lactic acid
stearic acid
a strong base

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

relaxation period
fatigue period
refractory period
latent period

In an isotonic contraction, the muscle ________.

changes in length and moves the "load"

never converts pyruvate to lactate

rapidly resynthesizes creatine phosphate and ATP

does not change in length but increases tension

The muscle cell membrane is called the ________.

sarcolemma
endomysium
epimysium
perimysium

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

A. muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments
B. neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke
C. motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments
D. neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke

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

A band
I band
M line
Z disc

Which of the following statements is true?

Cardiac muscle cells are found in the heart and large blood vessels.

Skeletal muscle cells are long and cylindrical with many nuclei.

Cardiac muscle cells have many nuclei.

Smooth muscle cells have T tubules.

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

glycolysis
hydrolysis
the citric acid cycle
the electron transport chain

Muscle tone is ________.

the condition of athletes after intensive training

the ability of a muscle to efficiently cause skeletal movements

a state of sustained partial contraction

the feeling of well-being following exercise

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

the action potential stops going down the overloaded T tubules

acetylcholinesterase destroying the ACh

the tropomyosin blocking the myosin once full contraction is achieved

calcium ions returning to the terminal cisternae

Which of the following statements is most accurate?

Muscle tension remains relatively constant during isotonic contraction.

The I band lengthens during isotonic contraction.

Myofilaments slide during isometric contractions.

T tubules may be sliding during isotonic contraction.

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

no muscle tension could be generated

cross bridge attachment would be optimum because of all the free binding sites on actin

maximum force production would result because the muscle has a maximum range of travel

ATP consumption would increase because the sarcomere is "trying" to contract

What part of the sarcolemma contains acetylcholine receptors?

motor end plate
part adjacent to another muscle cell
any part of the sarcolemma
end of the muscle fiber

Gary was injured in an automobile accident that severed the motor neurons innervating his quadriceps. Even though he has had extensive physical therapy, he is still suffering muscle atrophy. Why is the therapy not working?

A. In sarcopenia, there is a gradual loss of muscle mass as muscle proteins degrade faster than they can be replaced.
B. In denervation (disuse) atrophy, fibrous connective tissue replaces the muscle tissue that was lost. When atrophy is complete, fibrous tissue cannot be reversed to muscle tissue.
C. In Duchenne muscular dystrophy, the muscle enlarges due to fat and connective tissue, but the muscle fibers atrophy and degenerate irreversibly.
D. In myotonic dystrophy, there is a gradual loss of muscle mass as muscle proteins degrade faster than they can be replaced.
E. In myasthenia gravis, fibrous connective tissue replaces the muscle tissue that was lost. When atrophy is complete, fibrous tissue cannot be reversed to muscle tissue.

Aaron arrived at the hospital with the following symptoms: drooping eyelids; fatigue and weakness of his muscles; and difficulty talking, breathing, and swallowing. What was his diagnosis?

Sarcopenia
Myasthenia gravis
Myotonic dystrophy
Disuse atrophy
Duchenne muscular dystrophy

The nurse encourages the patient to do his own activities of daily living such as bathing, eating, dressing, and toileting activities. How do these activities promote physical conditioning?

The contraction of the muscles in these activities reverses sarcopenia and rebuilds muscle mass.

The contraction of the muscles in these activities helps maintain the shape, size, and strength of muscles, as well as joint mobility.

It does not. Only weight-bearing exercises maintain the shape, size and strength of muscles.

The contraction of the muscles in these activities reverses myotonic dystrophy and rebuilds muscle mass.

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

T
F

Muscle cells store more creatine phosphate than ATP resulting in the muscle having a reserve source of energy.

T
F

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

perimysium, endomysium, and epimysium
endomysium, epimysium, and perimysium
endomysium, perimysium, and epimysium
epimysium, endomysium, and perimysium
epimysium, perimysium, and endomysium

Choose the FALSE statement.

Skeletal muscle cells contain myoglobin.

Skeletal muscle cells have T tubules.

Skeletal muscle cells have glycosomes.

Skeletal muscle cells are multinucleated.

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

The smallest contractile unit of a muscle fiber is ________.

the elastic filament
the sarcomere
the myofilament
troponin

Thick myofilaments are made of ________.

tropomyosin
actin
troponin
myosin

The distance between Z discs ________ during muscle contraction.

stays the same
decreases
increases
decreases and then increases

The sliding filament model of contraction states that ________.

during contraction the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree

during contraction the thin myofilaments slide past T tubules so that the Z discs are overlapping

during contraction the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments no longer overlap

during contraction the thin myofilaments slide past the thick myofilaments so that calcium ions can be released from the sarcoplasmic reticulum

The first step toward generating a skeletal muscle contraction is ________.

binding of ATP to the myosin heads
stimulation of the muscle by a nerve ending
a rise in intracellular Ca2+ levels
binding of the myosin heads to actin

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

isometric
maximal
eccentric
concentric

When muscle cells break down glucose to generate ATP under oxygen deficient conditions, they will form ________.

lactic acid
glucose
fatty acids
glycogen

Slow oxidative muscle fibers are best suited for ________.

running a marathon
hitting a baseball
lifting heavy weights at the gym
running a 100-yard dash

Which of the following is TRUE?

Skeletal muscle lacks the coarse connective tissue sheaths that are found in smooth muscle.

Skeletal muscle fibers tend to be shorter than smooth muscle fibers.

Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not.

Skeletal muscle cells have one nucleus, but smooth muscle cells are multinucleated.

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

skeletal muscle
cardiac muscle
smooth muscle
cardiac and visceral smooth muscle

A stimulus traveling toward a synapse appears to open calcium ion channels at the presynaptic end, which in turn promotes fusion of synaptic vesicles to the axonal membrane.

T
F

Which of the following is false or incorrect?

A nerve impulse occurs if the excitatory and inhibitory effects are equal.

An inhibitory postsynaptic potential occurs if the inhibitory effect is greater than the excitatory, causing hyperpolarization of the membrane.

An excitatory postsynaptic potential occurs if the excitatory effect is greater than the inhibitory effect but less than threshold.

In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier.

T
F

Which of the following is NOT a type of circuit?

converging circuits
pre-discharge circuits
reverberating circuits
diverging circuits

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

T
F

Smooth muscles relax when intracellular Ca2+ levels drop but may not cease contractions.

T
F

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

the site of calcium regulation differs

actin and myosin interact by the sliding filament mechanism

the trigger for contraction is a rise in intracellular calcium

ATP energizes the sliding process

Which of the following is true about smooth muscle contraction?

Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements.

Certain smooth muscle cells can actually divide to increase their numbers.

Smooth muscle cannot stretch as much as skeletal muscle.

Smooth muscle has well-developed T tubules at the site of invagination.

Smooth muscle is characterized by all of the following except ________.

there are no sarcomeres

there are more thick filaments than thin filaments

there are noncontractile intermediate filaments that attach to dense bodies within the cell

it appears to lack troponin

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

cardiac muscle
multiunit smooth muscle
visceral smooth muscle
skeletal muscle

Which of the following statements is false or incorrect?

Under normal resting conditions, cardiac muscle tissue contracts and relaxes about 75 times per minute.

Cardiac muscle fibers can use lactic acid to make ATP.

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

Cardiac muscle contracts when stimulated by its own autorhythmic muscle cells.

Cells of unitary smooth muscle are found in the longitudinal and circular muscle layers of the intestine.

T
F

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

They are used for vision and hair raising.

They consist of muscle fibers that are structurally independent of each other.

They exhibit spontaneous action potentials.

They depend upon recruitment using the autonomic nervous system.

What special feature of smooth muscle allows it to stretch without immediately resulting in a strong contraction?

smooth muscle tone
low energy requirements
stress-relaxation response
slow, prolonged contractile activity

Isometric contraction leads to movement of a load.

T
F

Cardiac muscle makes most of its ATP via anaerobic pathways.

T
F

Duchenne muscular dystrophy could theoretically be cured if a technique was developed that would _________.

strengthen the dystrophin proteins that are present in the patient's muscle fibers

double the existing number of dystrophin molecules in the patient's muscle fibers

strengthen the thick and thin filaments in the patient's muscle fibers

none of the above

Which muscle cells have the greatest ability to regenerate?

skeletal
smooth
cardiac
no muscle can regenerate

Cardiac muscle has a limited regenerative capacity.

T
F

Smooth muscles are able to regenerate throughout life.

T
F

Which functional group has the major responsibility for producing a specific movement?

agonists
synergists
fixators
antagonists

What type of muscle assists an agonist by causing a like movement or by stabilizing a joint over which an agonist acts?

an antagonist
a synergist
an agonist
a prime mover

Muscles are only able to pull, they never push.

T
F

Muscles that help maintain upright posture are fixators.

T
F

Muscles that help to maintain posture are often called synergists.

T
F

Which of the following muscles is named for its origin and insertion?

trapezius
gluteus maximus
sternocleidomastoid
deltoid

When the term biceps, triceps, or quadriceps forms part of a muscle's name, what does it tell you about the muscle?

The muscle has two, three, or four functions, respectively.

The muscle has two, three, or four origins, respectively.

The muscle has two, three, or four insertions, respectively.

The muscle is able to change direction twice, three times, or four times faster than other muscles, respectively.

Axon diameter and degree of myelination determine nerve impulse conduction velocity.

T
F

The action potential is caused by permeability changes in the plasma membrane.

T
F

A pair of tweezers is a good example of a second-class lever.

T
F

Both first- and second-class levers operate at a mechanical disadvantage.

T
F

Although all skeletal muscles have different shapes, the fascicle arrangement of each muscle is exactly the same.

T
F

Regardless of type, all levers follow the same basic principle: effort farther than load from fulcrum = mechanical advantage; effort nearer than load to fulcrum = mechanical disadvantage.

T
F

The arrangement of a muscle's fascicles determines its range of motion and power.

T
F

Muscle power does not depend on the direction of the fascicles.

T
F

Diffusion movement always occurs from areas of greater to areas of lesser concentration.

T
F

In their resting state, all body cells exhibit a resting membrane potential ranging from -50 to about +50 millivolts.

T
F

Which cell organelle provides the majority of the ATP needed by the cell to carry out its metabolic reactions?

Golgi apparatus
ribosome
mitochondrion
lysosome

Microfilaments are thin strands of the contractile protein myosin.

T
F

The all-or-none phenomenon as applied to nerve conduction states that the whole nerve cell must be stimulated for conduction to take place.

T
F

During depolarization, the inside of the neuron's membrane becomes less negative.

T
F

Strong stimuli cause the amplitude of action potentials generated to increase.

T
F

A postsynaptic potential is a graded potential that is the result of a neurotransmitter released into the synapse between two neurons.

T
F

Large-diameter nerve fibers conduct impulses much faster than small-diameter fibers.

T
F

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

intracellular levels of Ca2+
extracellular levels of Na+
intracellular levels of Na+
extracellular levels of Ca2+

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

a muscle twitch
wave summation
recruitment
a tetanic contraction

The force of a muscle contraction is NOT affected by __________.

the degree of muscle stretch
the size of the muscle fibers stimulated
the frequency of the stimulation
the number of muscle fibers stimulated
the amount of ATP stored in the muscle cells

________ are the muscles primarily responsible for producing a particular movement.

Agonists
Synergists
Antagonists
Fixators

What is a muscle that provides the major force for producing a specific movement called?

a synergist
a fixator
an antagonist
an agonist

Which generalization concerning movement by skeletal muscles is not true?

During contraction the two articulating bones move equally.
Muscles produce movement by pulling on bones.
The bones serve as levers.
The movements produced may be of graded intensity.

Which of the following is NOT used as a criterion for naming muscles?

the shape of the muscle
the location of the muscle
the number of origins for the muscle
the locations of the muscle attachments
whether the muscle is controlled by the involuntary or voluntary nervous system

Which of the following muscles is named for its action?

gluteus minimus
levator labii superioris
biceps brachii
frontalis

The names of muscles often indicate the action of the muscle. What does the term levator mean?

The muscle functions as a synergist.
The muscle flexes and rotates a region.
The muscle is a fixator and stabilizes a bone or joint.
The muscle elevates and/or adducts a region.

A muscle that opposes, or reverses, a particular movement is a(n) ________.

fixator
synergist
antagonist
agonist

Which of these is not a way of classifying muscles?

the type of action they cause
muscle location
the type of muscle fibers
muscle shape

A patient is admitted to the hospital with exacerbation of multiple sclerosis (MS). She asks the nurse "Why did this have to happen to me again? I was doing so well." Why are some forms of MS characterized by periods of remission and exacerbation?

The axons are not damaged; growing numbers of potassium channels appear spontaneously in the demyelinated fibers, allowing conduction to resume.

The axons are damaged, and repair of the axons results in impulse propagation resuming.

The myelin sheaths are damaged, and repair of the myelin sheaths results in impulse propagation resuming.

The axons are not damaged; growing numbers of sodium channels appear spontaneously in the demyelinated fibers, allowing conduction to resume.

The axons are damaged, and repair of the myelin sheath results in impulse propagation resuming.

What does the central nervous system use to determine the strength of a stimulus?

frequency of action potentials
type of stimulus receptor
size of action potentials
origin of the stimulus

Immediately after an action potential has peaked, which cellular gates open?

potassium
chloride
calcium
sodium

Which of the following is true about the movement of ions across excitable living membranes?

Ions always move passively across membranes.

Sodium gates in the membrane can open in response to electrical potential changes.

Ions always move from an area of higher concentration to an area of lower concentration

Ions always move actively across membranes through leakage channels.

What type of stimulus is required for an action potential to be generated?

multiple stimuli
hyperpolarization
a threshold level depolarization
a suprathreshold stimulus

Which of the following is NOT true of an electrical synapse?

Communication through these synapses may be unidirectional or bidirectional.

They are specialized for release and reception of chemical neurotransmitters.

They are less common than chemical synapses.

Transmission across these synapses is very rapid.

Which of the following circuit types is involved in the control of rhythmic activities such as the sleep-wake cycle, breathing, and certain motor activities (such as arm swinging when walking)?

parallel after-discharge circuits
reverberating circuits
diverging circuits
converging circuits

An impulse from one nerve cell is communicated to another nerve cell via the ________.

synapse
receptor
cell body
effector

An inhibitory postsynaptic potential (IPSP) is associated with ________.

lowering the threshold for an action potential to occur

opening of voltage-regulated channels

hyperpolarization

a change in sodium ion permeability

Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane?

Specific potassium gates will open.

Sodium gates will open first, then close as potassium gates open.

A single type of channel will open, permitting simultaneous flow of sodium and potassium.

Specific sodium gates will open.

Caveolae are closely associated with all of the following except ________.

enzymes involved in cell regulation
enzymes involved in cell metabolism
receptors for hormones
lipid rafts

Which of the following statements is correct regarding net diffusion?

The greater the concentration gradient, the faster the rate.

Molecular weight of a substance does not affect the rate.

The lower the temperature, the faster the rate.

The rate is independent of temperature.

What is a membrane potential?

the ability of the cells to perform their specialized functions

the possibility of cell activity

cooperation between cells

a voltage or electrical charge across the plasma membrane

Which of the following is NOT a characteristic of peroxisomes?

They contain powerful enzymes called oxidases.

They aid in the neutralization of dangerous free radicals.

They contain powerful enzymes called catalases.

They contain powerful enzymes called acid hydrolases.

Which of the following is FALSE regarding the membrane potential?

The resting membrane potential occurs due to active transport of ions across the membrane due to the sodium-potassium pump.

The resting membrane potential is determined mainly by the concentration gradients and differential permeability of the plasma membrane to K+ and Na+ions.

In their resting state, all body cells exhibit a resting membrane potential.

The resting membrane potential is maintained by solely by passive transport processes.

Which of the following is NOT a function of the smooth endoplasmic reticulum?

steroid-based hormone synthesis

lipid metabolism and cholesterol synthesis

breakdown of stored glycogen to form free glucose

protein synthesis in conjunction with ribosomes

Most skeletal muscles of the body act in ________.

first-class lever systems
power lever systems
third-class lever systems
second-class lever systems

If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon ________.

the impulse would move to the axon terminal only

muscle contraction would occur

the impulse would spread bidirectionally

the impulse would move to the axon terminal only, and the muscle contraction would occur

In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment? The interior is ________.

negatively charged and contains more sodium
positively charged and contains more sodium
negatively charged and contains less sodium
positively charged and contains less sodium

A second nerve impulse cannot be generated until ________.

proteins have been resynthesized
the membrane potential has been reestablished
all sodium gates are closed
the Na ions have been pumped back into the cell

Which of the following is not true of graded potentials?

They can be called postsynaptic potentials.

They can form on receptor endings.

They are short-lived.

They increase amplitude as they move away from the stimulus point.

When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ________.

action potential
postsynaptic potential
excitatory potential
generator potential

Saltatory conduction is made possible by ________.

large nerve fibers
diphasic impulses
erratic transmission of nerve impulses
the myelin sheath

Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials?

mechanically gated channel
ligand-gated channel
leakage channel
voltage-gated channel

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________.

depolarization
absolute refractory period
resting period
repolarization

Local anesthetics block voltage-gated Na+ channels, but they do not block mechanically gated ion channels. Sensory receptors for touch (and pressure) respond to physical deformation of the receptors, resulting in the opening of specific mechanically gated ion channels. Why does injection of a local anesthetic into a finger still cause a loss of the sensation of touch from the finger?

The local anesthetic prevents Na+ from causing the initial depolarization of this sensory receptor.

The local anesthetic prevents any type of repolarization of this sensory receptor.

Touch stimulation of this sensory receptor requires that there be a simultaneous opening of voltage-gated Na+ channels and mechanically gated ion channels.

Touch stimulation of this sensory receptor will open the mechanically gated ion channels, but action potentials are still not initiated because propagation of an action potential requires the opening of voltage-gated Na+ channels.

In multiple sclerosis, the cells that are the target of an autoimmune attack are the _________.

neurons
muscle cells
Schwann cells
oligodendrocytes

Which of the following movements demonstrates a first-class lever?

lifting a rock with your right hand and arm

flexing your knee to raise your heel toward your buttocks

raising your head up off your chest

standing on your toes

Which type of lever is demonstrated by using scissors?

a first-class lever
a second-class lever
a third-class lever
a fourth-class lever

What is the major factor controlling how levers work?

the direction the load is being moved

the structural characteristics of the muscles of the person using the lever

the difference in the positioning of the effort, load, and fulcrum

the weight of the load

What is the main factor that determines the power of a muscle?

the shape

the total number of muscle cells available for contraction

the length

the number of neurons innervating it

What are the levers that operate at a mechanical advantage called?

speed levers
dysfunctional levers
functional levers
power levers

First-class levers ________.

have load at one end of the lever, fulcrum at the other, and effort applied somewhere in the middle

are typified by tweezers or forceps

in the body can operate at a mechanical advantage or mechanical disadvantage, depending on specific location

are the type using joints forming the ball of the foot as formed in raising the body on the toes

If a lever operates at a mechanical disadvantage, it means that the ________.

lever system is useless

load is far from the fulcrum and the effort is applied near the fulcrum

effort is farther than the load from the fulcrum

load is near the fulcrum and the effort is at the distal end

If L = load, F = fulcrum, and E = effort, what type of lever system is described as LEF?

fourth-class lever
second-class lever
first-class lever
third-class lever

Which of the following would NOT diffuse through the plasma membrane by means of simple diffusion?

glucose
a lipid soluble vitamin
oxygen
a steroid hormone

Which of the following describes the plasma membrane?

the phospholipid bilayer surrounding the cell

a single-layered membrane that surrounds the nucleus of the cell

a membrane composed of tiny shelves or cristae

a double layer of protein enclosing the plasma

Which of the following is a difference between primary and secondary active transport?

Primary active transport is driven by secondary active transport.

Primary active transport is used to transport sugars and amino acids across the plasma membrane, while secondary active transport includes the sodium-potassium pump.

In primary active transport, the transport protein gets phosphorylated; in secondary active transport, the transport protein is not phosphorylated.

Energy is required for primary active transport, but energy is not required for secondary active transport.