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Ch 10

Terms in this set (149)

The characteristic of muscle that allows it to be passively stretched is
A. conductivity. B. elasticity.
C. excitability. D. extensibility. E. contractility.
d
Which are possible functions of skeletal muscles?
a: Maintenance of posture
b: Both highly coordinated and localized simple movements
c: Temperature regulation
d: Support of certain body organs
e: Regulation of the movement of material through certain body tracts
A. a, b, e
B. a, b, c
C. a, b, c, e
D. a, b, c, d
E. a, b, c, d, e
e
t or f The floor of the pelvic cavity includes skeletal muscles that function to support organs in that cavity.
t
A circular muscle band that contracts at an orifice is also known as a _____________
sphincter
The property of muscle tissue that allows an impulse to travel down the entire length of the cell membrane is
A. elasticity.
B. conductivity. C. extensibility. D. contractility. E. responsibility.
b
The spring-like property that returns muscle to its original length after a contraction ends is
A. extensibility. B. elasticity.
C. contractility. D. treppe effect. E. conductivity.
b
In general, a skeletal muscle is composed of a: connective tissue sheaths
b: nerves
c: arteries
d: veins
e: muscle fibers
A. a, b, c, e
B. a, b, d, e
C. b, c, d, e
D. a, b, c, d
E. a, b, c, d, e
e
Which is the correct order of the connective tissue layers of a skeletal muscle, beginning with the most superficial? a: Endomysium
b: Epimysium
c: Perimysium
A. a, b, c
B. b, a, c
C. c, a, b
D. b, c, a
E. c, b, a
d
The structure responsible for attaching muscle to bone is a
A. sphincter. B. ligament. C. fascia.
D. tendon. E. myofibril.
d
A flat, thin structure made of dense connective tissue that serves to attach a muscle to a bone (or to another muscle) is a(n)
A. aponeurosis.
B. tendon.
C. perimysium.
D. myolemma.
E. superficial fascia.
a
The neurons that stimulate muscle contraction are called _____ neurons. A. sensory
B. contractile
C. inhibitory
D. motor
E. association
d
t or f Deep fascia is also known as muscular fascia; it is composed of dense irregular connective tissue.
t
The multiple nuclei in skeletal muscle cells are the result of the
A. fusion of myoblasts.
B. cytokinesis of embryonic satellite cells.
C. spontaneous development of nuclei in embryonic cells. D. stimulation of fibroblasts by hormones.
E. action of testosterone on mesenchyme cell.
a
t or f Because skeletal muscle cells are so close together, muscle contains very few blood vessels.
f
t or f The connections between the nervous system and skeletal muscle allow for voluntary control of movement.
t
t or f Satellite cells are multinucleate.
f
The membranous network that wraps around myofibrils and holds relatively high concentrations of calcium is known as the
A. sarcolemma.
B. T-tubule.
C. sarcoplasmic reticulum. D. sarcomere.
E. Golgi body.
c
Invaginations of the muscle cell membrane that extend deep into the cell are known as the

A. T-tubules.
B. terminal cisternae. C. titin complexes. D. Z-discs.
E. end plates.
a
. Which are the reservoirs that store the calcium required for muscle contraction? A. Synaptic vesicles
B. Synaptic clefts
C. Terminal cisternae
D. Peroxisomes E. Mitochondria
c
Which protein makes up the thick filaments? A. Myosin
B. Actin
C. Tropomyosin
D. Troponin E. Myopathy
a
Which is not a protein found in thin filaments? A. Actin
B. Troponin
C. Tropomyosin
D. Sarcomyosin
E. No exceptions; all are found in thin filaments
d
Each thick filament contains about ______ protein molecules (each molecule has two heads and two braided tails).
A. 2
B. 20
C. 200
D. 2000
c
A skeletal muscle cell contains hundreds to thousands of _________, which are complex organelles; they are cylindrical in shape—about 2 micrometers in diameter and as long as the cell.
A. myofibrils
B. microfilaments C. sarcomeres
D. T-tubules
E. sarcolemma
a
What is the letter associated with the dark bands in a sarcomere?
A. I
B. A
C. Z
D. M
E. H
b
Which letter is associated with the line that is a thin protein structure that serves as an attachment site for thin filament ends?
A. I
B. A
C. Z
D. M
E. H
c
Which letter is associated with a zone (in a relaxed muscle) that is a little more lightly shaded because only thick filaments are present?
A. I
B. A
C. M
D. Z
E. H
e
Which letter is associated with the light band and contains thin filaments only?
A. I
B. A
C. M
D. Z
E. H
a
Which of the following structures has the active sites to which the heads of the thick filaments will bind?
A. Actin
B. Troponin
C. Tropomyosin D. Myosin
E. Sarcoplasm
a
. A sarcomere is defined as the distance from one _____ to the next adjacent ____ . (The same answer fills in both spaces.)
A. Z disc
B. I band
C. H zone
D. A band
E. M line
a
__________ is a protein that anchors myofibrils that are adjacent to the sarcolemma to proteins in the sarcolemma.
dystrophin
Myoglobin is a molecule within muscle cells that can bind
A. creatine phosphate.
B. oxygen.
C. hemoglobin.
D. acetylcholine.
E. ATP.
b
A typical skeletal muscle cell contains approximately _____ mitochondria.
A. 3
B. 30
C. 300
D. 3000
c
The presence of mitochondria and myoglobin facilitate _________ respiration in muscle cells.
A. aerobic
B. anaerobic
a
One feature that helps provide fast energy to a muscle cell is the presence of granules containing the complex carbohydrate
A. creatine phosphate. B. myoglobin.
C. glycogen.
D. nebulin.
E. hemoglobin.
c
A motor unit consists of
A. multiple motor neurons and multiple muscle fibers.
B. a single motor neuron and the multiple muscle fibers it controls.
C. multiple motor neurons and the one muscle fiber they control.
D. one synaptic terminal button, a cleft, and an acetylcholine receptor.
E.
an end plate, a T-tubule, and sarcoplasmic reticulum.
b
t or f Muscles that are used for precisely controlled movements generally contain large motor units.
f
A motor unit within the powerful quadriceps muscle would
A. contain several motor neurons.
B. be much like those in the eye muscles. C. generally contain less than ten fibers.
D. generally contain several hundred fibers.
d
Fibers from one motor unit
A. are clustered together within one fascicle of the muscle.
B. are dispersed throughout most of the muscle.
b
The narrow space that separates the motor neuron and the skeletal muscle fiber in a neuromuscular junction is called the
A. motor end plate. B. synaptic vesicle. C. synaptic cleft. D. synaptic knob.
c
t or f The neuromuscular junction is usually located at one of the two ends of the muscle fiber.
f
Which structures are reservoirs that store acetylcholine?
A. Synaptic vesicles
B. Synaptic clefts
C. Terminal cisternae
D. Lysosomes E. Sarcomeres
a
When an impulse arrives at the knob of the motor neuron, calcium

A. enters through active transport pumps and triggers the release of transmitter.
B. enters through voltage-gated channels and triggers the release of transmitter. C. exits through active transport pumps and brings transmitter with it.
D. exits through voltage-gated channels and triggers transmitter release.
E. is released from synaptic vesicles.
b
Acetylcholine is released from a neuron
A. by a primary active transport pump.
B. by rapid diffusion when a voltage-gated ion channel opens for it. C. through exocytosis when a vesicle fuses with the membrane.
D. by conduction through a gap junction from nerve to muscle
c
Acetylcholine exerts its effect by
A. stimulating the motor neuron's synaptic knob. B. binding to receptors at the motor end plate. C. activating acetylcholinesterase.
D. allowing calcium to enter the cell.
b
Which is the neurotransmitter that causes the release of calcium ions from reservoirs within the muscle cell and thereby initiates the steps of contraction?
A. Acetylcholinesterase
B. Acetylcholine
C. Serotonin
D. Norepinephrine
b
. The calcium ions involved in skeletal muscle contraction bind to a(n)______ subunit. A. myosin
B. actin
C. elastin
D. tropomyosin E. troponin
e
An end plate potential is an event that involves a gain of
A.
positive charge along the inside of the cell membrane, as potassium rapidly enters.
B.
positive charge along the inside of the cell membrane, as sodium rapidly enters.
C.
negative charge along the inside of the cell membrane, as potassium rapidly enters.
D.
negative charge along the inside of the cell membrane, as sodium rapidly ente
b
The action potential of a muscle fiber occurs

A. at the end plate.
B. along the sarcolemma and down the T-tubules. C. within the sarcoplasmic reticulum.
D. in the mitochondria.
b
The repolarization of the action potential involves the opening of
A. chemically gated Na+ channels. B. voltage-gated Na+ channels.
C. chemically gated K+ channels. D. voltage-gated K+ channels
d
Which sequence correctly lists the changes that allow the thick and thin filaments to slide past one another in skeletal muscle contraction?
A. Attach - pivot - detach - return
B. Pivot - attach - return - detach
C. Attach - detach - pivot - return
D. Return - pivot - attach - detach
E. Pivot - attach - detach - return
a
During which phase of the crossbridge cycle is ATP split into ADP and Pi?
A. Immediately preceding the detachment of the myosin head
B. Immediately preceding the resetting of the myosin head
C. Immediately preceding the power stroke
b
A power stroke involves
A. an actin molecule pulling a myosin molecule toward the M-line.
B. a thin filament shortening in length and thereby shortening the sarcomere. C. a myosin head pulling a thin filament toward the center of the sarcomere. D. a thick filament pushing an actin filament towards the nearest Z-line.
c
A drug that inhibited acetylcholinesterase would result in
A.
a failure to stimulate the muscle due to decreased ACh release.
B.
enhanced stimulation of the muscle due to decreased ACh breakdown.
C.
enhanced stimulation of the muscle due to enhanced ACh release.
D.
poor muscle stimulation due to enhanced ACh breakdown.
b
For relaxation to occur,
A.
ACh receptors close and Ca++ channels on the sarcoplasmic reticulum close.
B.
ACh receptors close and Ca++ channels on the sarcoplasmic reticulum open.
C.
ACh receptors open and Ca++ channels on the sarcoplasmic reticulum close.
D.
ACh receptors open and Ca++ channels on the sarcoplasmic reticulum open.
a
For relaxation to occur,
A.
calcium leaves the sarcoplasmic reticulum, and troponin binds calcium and blocks the binding sites on actin.
B. calcium enters the myofibril, it detaches from myosin, and the binding sites on myosin become inactive.
C. sarcoplasm calcium levels fall, calcium is removed from troponin, and tropomyosin blocks binding sites on actin.
D. extracellular calcium levels fall, calcium is pumped into the myofibril, and tropomyosin slides away from actin.
c
When a muscle relaxes,

A. crossbridges form and muscle extensibility returns the muscle to rest length.
B. crossbridges form and muscle elasticity returns the muscle to rest length.
C. crossbridges stop forming and muscle elasticity returns the muscle to rest length.
D. crossbridges stop forming and muscle extensibility returns the muscle to rest length
c
Relaxation is facilitated by the release of passive tension that developed in cablelike __________ proteins that were compressed during contraction.
connectin
Phosphate transfer is used for
A. immediate ATP needs and is dependent on oxygen.
B. immediate ATP needs and is not dependent on oxygen.
C. long term ATP needs and is dependent on oxygen.
D. long term ATP needs and is not dependent on the presence of oxygen.
b
t or f . Myosin kinase catalyzes the transfer of Pi from creatine phosphate to ADP.
f
Glycolysis is an
A. aerobic process that occurs in the cytosol.
B. aerobic process that occurs in the mitochondria. C. anaerobic process that occurs in the cytosol.
D. anaerobic process that occurs in the mitochondria.
c
The net energy yield from one glucose molecule through the process of glycolysis is
A. 2 ATP.
B. 6 ATP.
C.
30 ATP.
D. 36 ATP.
A
t or f Aerobic respiration involves the oxidation of pyruvate
t
The electron transport system refers to oxidative phophorylation using the coenzymes FADH2 and _______.
NADH
For a sprint lasting 60 seconds, ATP is supplied primarily by
A.
aerobic respiration only.
B.
phosphate transfer and glycolysis.
C.
conversion of lactate to pyruvate.
D.
phosphate transfer only.
b
When someone engages in exercise that requires more oxygen than is available, they develop a(n) _____ _______ (2 words), which results in heavy breathing for several minutes after the exercise is complete
oxygen debt
t or f Heavy breathing to compensate for an oxygen debt helps the body convert lactate to glucose.
t
t or f in general, fast-twitch fibers generate less power than slow-twitch fibers.
f
t or f Compared to slow-twitch fibers, fast-twitch fibers respond to a stimulus with less delay and with a shorter contraction duration.
t
Oxidative fibers are
A. red and fatigue-resistant. B. red and fatigable.
C. white and fatigue-resistant. D. white and fatigable
a
t or f Glycolytic muscle fibers tend to be very rich in myoglobin and mitochondria.
f
. The type of fibers specialized to continue contracting for extended periods of time, as would be required in running a marathon, for example, are _____ fibers.
A.
fast-twitch
B.
slow-twitch
C. intermediate
b
The vascular supply to slow-twitch muscle fibers is ______ the network of capillaries around fast-twitch muscle fibers.
A. more extensive than
B. less extensive than
C. the same as that of
a
"Intermediate fiber" is another name for
A.
a fast-twitch, glycolytic fiber.

B.
a fast-twitch, oxidative fiber.
C.
a slow-twitch, glycolytic fiber.
D.
a slow-twitch, oxidative fiber.
b
76. Which fibers dominate many of the back and calf muscles that contract almost continually to maintain posture?
A.
Slow-twitch
B.Fast-twitch
C. Intermediate
A
Muscles of the eye and hand have a high percentage of _______ fibers.
A.
fast-twitch
B.
slow-twitch
a
t or f One's genes have a greater impact than exercise habits in determining the proportion of fast-twitch and slow-twitch fibers throughout the body.
t
t or f The contraction phase of a muscle twitch has a shorter duration than the relaxation phase.
t
Events of excitation contraction coupling, such as the release of calcium from intracellular stores, occur during the ________ period of a muscle twitch.
A. relaxation
B. contraction
C. latent
c
t or f A subthreshold stimulus evokes only a small muscle twitch instead of a full tetanic contraction
f
Release of crossbridges and a decline in muscle tension characterize the _______ period of a twitch. A. contraction
B. latent
C. relaxation
c
A graph of a muscle twitch contains three periods. The period during which there is no change in external muscle tension (and no change in muscle length) is the ________ period.
latent
The increase in muscle tension that occurs with an increase in the intensity (voltage) of a stimulus is called
A. recruitment.
B. treppe.
C. wave summation. D. incomplete tetany
a
Consider the difference between lifting a light pad of paper versus a heavy textbook. The primary way the level of force of muscle contraction is controlled is by
A. recruiting a different number of motor units.
B. activating different regions of the muscle.
C. activating the motor units at a different frequency.
D. altering the number of crossbridges each individual fiber uses.
a
"Staircase" and "warming-up effect" refer to ___________, an increased muscle response to a constant stimulus.
A. wave summation
B. treppe
C. multiple motor unit summation D. incomplete tetany
E. isotony
b
t or f In a graph of wave summation, the tension level returns to baseline between each peak of force.
f
A continuous, smooth contraction of muscle in which twitches are fully fused is referred to as _________.
tetany
. In a lab, wave summation is demonstrated by increasing the _________ of the stimulus.
A. intensity
B. frequency
C. capacitance
D. warm up time
b
t or f During REM sleep, muscle tone decreases significantly.
t
Muscle tone is a result of _________ nervous system activity, and it acts to _________ joint position.
A. involuntary, stabilize
B. involuntary, continuously vary
C. voluntary, stabilize
D. voluntary, continuously vary
a
Which contraction occurs when you try (unsuccessfully) to move a wall? A. Isometric
B. Isotonic
a
When a muscle is isometrically contracted, its length _______ change. A. does
B. does not
b
The top long-distance runners probably have _______ proportion of slow muscle fibers in their leg muscles.
A. a higher B. a lower C. the same
a
The most prevalent of skeletal muscle fibers in the body are _____ fibers.
A.
slow-twitch
B.
fast-twitch
C. intermediate
b
One of the reasons you might struggle to lift a heavy object with your arm fully extended is because
A. in extension, the proximity of Z discs to thick filaments restricts the sliding movement within sarcomeres.
B. full extension results in decreased overlap between thick and thin filaments in the muscle.
C. in that posture, some myosin heads overlap actin in the wrong orientation and tug actin in the wrong direction.
D.
motor neurons cannot release as much ACh in that posture.
b
t or f In general, a muscle's resting length is its optimal length for force generation.
t
A reduced ability to generate tension due to recent exertion of force is known as muscle ________.
fatigue
t or f One of the most crucial factors in the development of fatigue appears to be a depletion of ATP.
f
Increased phosphate ion concentration is believed to contribute to fatigue by interfering with
A. calcium release from the sarcoplasmic reticulum.
B. levels of available ATP to provide energy for contraction.
C. phosphate release by myosin heads during crossbridge cycling. D.
ACh release by synaptic knobs of motor neurons.
c
Which may occur as a result of muscle atrophy?
A. Reduction in muscle size
B. Fibers become weaker
C. Muscle loses tone
D. Fibers waste away and die
E.
All of the choices are correct.
e
With increased age, skeletal muscles show
A. a decrease in the number of myofibrils. B. an increase in muscle fiber diameter.
C. no change in oxygen storage capability. D. increased glycogen reserves.
E. a tendency to fatigue less rapidly.
a
During aging, muscle is often replaced by dense connective tissue, a process called ________
fibrosis
Lifting weights will cause muscles to enlarge. This is primarily due to
A.
an increase in the number of muscle cells.
B.
an increase in the size of muscle cells.
b
A term that describes the change in muscle following a lack of exercise is
A. proliferation. B. hypertrophy. C. convergence. D. atrophy.
E. myofascia.
d
The type of muscle fibers that have only a single nucleus, both thick and thin filaments, but no Z discs, are
A. skeletal.
B. cardiac.
C. smooth.
D. cardiac and smooth. E. cardiac and skeletal.
c
Growth of the uterus during pregnancy is accomplished by _________ of its smooth muscle. A. neither hypertrophy nor hyperplasia
B. both hypertrophy and hyperplasia
C. hypertrophy but not hyperplasia
D. hyperplasia but not hypertrophy
b
t or f Smooth muscle cells tend to be shorter but thicker than skeletal muscle cells.
f
Within smooth muscle cells, intermediate filaments are linked by dense _________ at points where they attach on the inner surface of the cell membrane.
plaques
The latchbridge mechanism of myosin heads is a property of ________ muscle. A. cardiac
B. skeletal
C. smooth
c
To initiate a smooth muscle cell contraction, calcium enters the cell and binds to
A.
troponin, which then activates myosin light-chain kinase.
B.
calmodulin, which then binds to and activates myosin light-chain kinase. C. a myosin head, which then activates calmodulin.
D.
myosin light-chain kinase, which then hydrolyzes ATP.
E. a phosphatase, which then removes the tropomyosin blockade.
b
t or f Myosin light-chain phosphatase is an enzyme that dephosphorylates the myosin heads in smooth muscle, which stops ATPase activity and fosters relaxation of smooth muscle
t
t or f Energy requirements for smooth muscle contractions are generally higher than those for skeletal muscle contractions.
f
The branch of the nervous system that helps govern smooth muscle contraction is the _______ nervous system.
A. autonomic
B. somatic
a
t or f Similar to skeletal muscle cells, all smooth muscle cells are excited by ACh.
f
When smooth muscle is stretched for a prolonged period of time, it responds by

A. contracting. B. relaxing.
b
Smooth muscle tissue in which cells are individually sent signals to contract (rather than contracting in unison) is referred to as
A. single-unit. B. multiunit.
b
The iris of the eye contains
A. skeletal muscle.
B. multiunit smooth muscle. C. single-unit smooth muscle. D. cardiac muscle.
b
The most abundant form of smooth muscle is
A. single-unit, which is also known as visceral smooth muscle.
B. cardiac muscle, which is also known as visceral smooth muscle.
C. multiunit, which is also known as visceral smooth muscle.
D. multiunit, which is also known as varicose muscle.
E. single-unit, which is also known as somatic nervous system muscle.
a
Rather than tightly coupled synapses between neurons and muscle cells, single-unit smooth muscle contains
A. gap junctions that connect neurons to smooth muscle cells.
B. varicosities of a subset of muscle fibers so that individual cells can be separately stimulated.
C. diffuse junctions where neuron varicosities are responsible for neurotransmitter release.
D. plaques and caveolae that contain multiple hormone receptors for discrete endocrine control.
c
This sarcomere depicts relaxed muscle. What does number 1 refer to?
A. A band B. H zone C. Z disc D. M line E. I band
a
This sarcomere depicts relaxed muscle. Which number identifies the M line?
A. 1
B. 3
C. 4
D. 5
c
t or f In the hierarchy of skeletal muscle fiber components, the myofibril is made up of myofilaments.
t
t or f The fat and connective tissue that encircle a beef steak form the endomysium.
f
t or f The T-tubules and sarcoplasmic reticulum are unique to muscle fibers
t
t or f The embryonic-like cells that remain in adult skeletal muscle tissue are known as satellite cells.
t
t or f . During skeletal muscle fiber contraction, the I bands and H zones narrow
t
t or f The return of a contracted muscle fiber to its resting length is an active (energy requiring) process.
f
t or f During skeletal muscle contraction, more force is created when more motor units are activated
t
t or f In an isotonic contraction, the tension produced exceeds the resistance and muscle fibers will shorten.
t
t or f Slow-twitch fibers are specialized to continue contracting for extended periods of time without experiencing fatigue
t
t or f The metabolic reactions within fast-twitch fibers derive much of their energy from aerobic respiration.
f
The type of muscle fibers that are striated, form Y-shaped branches, and are joined by intercalated discs are
A. skeletal.
B. cardiac.
C. smooth.
D. voluntary.
E. skeletal and voluntary.
b
t or f Cardiac muscle cells tend to be thicker and shorter than skeletal muscle cells.
t
t or f The number of satellite cells in skeletal muscle steadily decreases with age
t
t or f Smooth muscle tissue is found in the organs of the digestive tract, the walls of blood vessels, and the iris.
t
Each skeletal muscle is composed of _____________, which are bundles of muscle fibers.
fascicles
The _____________ is the connective tissue covering of a fascicle
perimysium
The _____________ is the innermost connective tissue layer that surrounds each muscle fiber.
endomysium
One of the names for the areolar connective tissue and adipose connective tissue that separates muscle from skin is ______________ fascia.
superficial
The junction between an axon and the muscle fiber itself is called a _____________ junction.
neuromuscular
. The plasma membrane of a skeletal muscle fiber is called the ______________.
sarcolemma
On a muscle fiber, the two terminal cisternae and the centrally placed T-tubule form a structure called a _____________
triad
During muscle contraction, myosin heads attach to actin and thereby form connections called ___
crossbridges
The functional contractile unit of a skeletal muscle fiber is called a _______________.
sarcomere
The enzyme _____________ resides in the synaptic cleft and breaks down molecules of ACh.
acetylcholinesterase
Skeletal muscle contraction requires large amounts of energy in the form of ___________ in order to complete the sequence of cyclic events that lead to sarcomere shortening.
ATP
When tension output exceeds resistance and the muscle exerts a constant force as it changes length, the contraction is described as _________.
isotonic
An increase in the size of a muscle fiber is called _________________.
hypertrophy
___________ muscle fibers have large myoglobin stores, slow contraction velocity, and the highest resistance to fatigue.
slow twitch
t or f When a skeletal muscle fiber is at rest, there is more sodium outside the cell as compared to the sarcoplasm.
t
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