Pregunta 1
Pregunta
Which of the following actions is caused by contraction of a skeletal muscle?
Pregunta 2
Pregunta
The capacity of a muscle cell to shorten forcefully is known as
Respuesta
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contractility
-
excitability
-
extensibility
-
elasticity
Pregunta 3
Pregunta
Muscles exhibit the property of excitability. This means that the muscle
Respuesta
-
shortens in legnth
-
recoils to its original resting length
-
stretches beyond its normal length
-
responds to stimulation by the nervous system
Pregunta 4
Pregunta
Identify the statement concerning general functional characteristics of muscle that is true.
Respuesta
-
muscle tissue shortens forcefully but lengthens passively
-
muscle tissue shortens passively but lengthens forcefully
-
muscle tissue can get shorter, but cannot get longer
-
muscle tissue can get longer, but cannot get shorter
Pregunta 5
Pregunta
Identify the statement concerning the skeletal muscle that is true.
Respuesta
-
It comprises about 20% of the body's weight
-
It propels urine through the urinary tract
-
Its function is largely under involuntary control
-
It is powered by ATP
Pregunta 6
Pregunta
Which type of muscle tissue would cause flexion and extension of the arm?
Respuesta
-
skeletal muscle
-
smooth muscle
-
cardiac muscle
Pregunta 7
Pregunta
Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the
Respuesta
-
number of muscle fibers
-
size of muscle fibers
-
number of striations
-
number of muscle cells
Pregunta 8
Pregunta
Skeletal muscle develops from multinucleated cells called
Respuesta
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fascicles
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myoblasts
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myofibrils
-
myotomes
Pregunta 9
Pregunta
Endomysium is a delicate network of loose connective tissue that
Respuesta
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surrounds each muscle fiber
-
forms a sheath around a fasciculus
-
is composed of elastic fibers
-
separates individual muscles
-
penetrates muscle fibers
Pregunta 10
Respuesta
-
surrounds individual muscles
-
separates muscle fibers
-
connects muscles to bone
-
is a type of muscle tissue
-
is a type of nerve tissue
Pregunta 11
Pregunta
Which of the following connective tissue layers is outside all the others?
Respuesta
-
perimysium
-
endomysium
-
epimysium
-
paramysium
-
sarcolemma
Pregunta 12
Pregunta
List the following structures in order from smallest to largest. 1. muscle fiber 2. myofilament 3. myofibril 4. muscle fasciculus
Respuesta
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4,3,2,1
-
2,1,4,3
-
2,3,1,4
-
1,2,3,4
Pregunta 13
Pregunta
Muscle myofibrils
Respuesta
-
are found in the sacrolemma
-
extend from the sarcolemma to the T-tubule
-
contain myosin and actin myofilaments
-
hold muscle cells together
-
do not apper striated
Pregunta 14
Pregunta
The region of the sarcomere that contains both actin and myosin myofilaments is called the
Respuesta
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I band
-
A band
-
Z disk
-
H zone
Pregunta 15
Pregunta
A sarcomere extends from
Respuesta
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one Z disk to an adjacent Z disk
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one T tubule to the next T tubule
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the middle of the I band to the middle of the A band
-
the H zone to the I band
-
the M line to the next M line
Pregunta 16
Pregunta
Which of the following would contribute to muscular fatigue in the muscle fiber?
Respuesta
-
the emotional state of an individual
-
depletion of ATP reserves
-
inability of the motor neuron to produce sufficient quantities of acetylcholine
-
depletion of neurotransmitter
-
blocked receptors in the postsynaptic membrane
Pregunta 17
Pregunta
Lack of acetylcholinesterase in the synaptic cleft would result in
Respuesta
-
a decrease in acetylcholine production by the motor neuron
-
continuous stimulation of the motor end plate
-
rapid degradation of acetylcholine
-
relaxation of the muscle
-
continuous stimulation of the presynaptic membrane
Pregunta 18
Pregunta
A bi-product of anaerobic respiration in muscle cells is
Respuesta
-
uric acid
-
hydrochloric acid
-
lactic acid
-
carbonic acid
Pregunta 19
Pregunta
Which of the following is composed of myosin molecules?
Respuesta
-
thick myofilaments
-
I bands
-
Z disks
-
sarcolemma
-
tropomyosin
Pregunta 20
Respuesta
-
is a time during which the tissue cannot respond
-
results in complete and incomplete tetanus
-
is a condition in which the muscle fiber only partially relaxes between contractions
-
is a condition in which stimuli occur so rapidly that there are no intervening relaxations
-
is a constant tension produce produced by muscles for long periods of time
Pregunta 21
Pregunta
A myofibril is the
Respuesta
-
cell membrane of a muscle fiber
-
cytoplasm of muscle cells
-
structural and functional unit of the skeletal muscle fiber
-
protein strand composed of actin
-
contractile thread that extends the length of the muscle fiber
Pregunta 22
Pregunta
The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called
Respuesta
-
neuromuscular junctions
-
sarcomeres
-
myofilaments
-
Z disks
-
cell body of neuron
Pregunta 23
Pregunta
Acetylcholine is released from the synaptic terminal by the process of
Respuesta
-
exocytosis
-
diffusion
-
phagocytosis
-
active transport
-
endocytosis
Pregunta 24
Pregunta
You are hired to work in a lab to measure the rate of human muscle contraction. Which of the following might decrease in quantity in muscle cells undergoing contractions?
Respuesta
-
ATP
-
carbon dioxide
-
water
-
lactic acid
-
sodium
Pregunta 25
Pregunta
Which of the following is true about skeletal muscle?
Respuesta
-
Sensory neurons stimulate muscle to contract
-
There are very few blood vessels in skeletal muscle
-
Every muscle fiber receives a branch of an axon from the nerve
-
There are very few nerve fibers in a muscle
-
All of these are true
Pregunta 26
Pregunta
Which of the following statements regarding the sliding filament model is false?
Respuesta
-
actin and myosin do not shorten during contraction
-
both actin and myosin myofilaments shorten during contraction
-
the sarcomere shortens
-
the I band and H zones become narrower during contraction
-
the A band remains constant in length
Pregunta 27
Pregunta
Rigor mortis occurs after death because
Respuesta
-
cross-bridges form but can't release
-
calcium is actively transported back to the sarcoplasmic reticulum
-
anaerobic respiration is ocurring
-
myosin levels decline at death
-
cross-bridges never form
Pregunta 28
Pregunta
Which of the following events occurs on the postsynaptic membrane?
Respuesta
-
acetylcholine production
-
rapid degradation of acetylcholine
-
release of neurotransmitter
-
neurotransmitter combines with a receptor molecule
-
release of calcium ions
Pregunta 29
Pregunta
The model that describes the contraction of the muscle is called the
Pregunta 30
Pregunta
The sarcolemma is the
Respuesta
-
cell membrane of a muscle fiber
-
cytoplasm of muscle cells
-
structural and functional unit of the skeletal muscle cell
-
contractile thread that extends the length of the muscle fiber
-
protein strand composed of actin
Pregunta 31
Pregunta
A sarcomere is the
Respuesta
-
cell membrane of a muscle fiber
-
cytoplasm of muscle cells
-
structural and functional unit of the skeletal muscle cell
-
contractile thread that extends the length of the muscle fiber
-
protein strand composed of actin or myosin
Pregunta 32
Pregunta
If sodium ions cannot enter a muscle fiber in response to a stimulus,
Respuesta
-
contraction cannot occur
-
relaxation cannot occur
-
sodium ions will be released from the sarcoplasmic reticulum instead
-
the active sites are left exposed
-
the action potential travels into the muscle anyway
Pregunta 33
Pregunta
The active sites to which cross-bridges attach are found on the
Respuesta
-
sarcoplasmic reticulum
-
actin myofilaments
-
Z disks
-
T tubules
-
myosin myofilaments
Pregunta 34
Pregunta
During short periods of intense exercise, energy in muscles is primarily derived from
Pregunta 35
Pregunta
A drug that interferes with the active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum would result in
Respuesta
-
relaxation of the muscle fiber
-
contraction with no relaxation
-
muscle hypertrophy
-
fibrosis of the muscle
-
an imbalance of blood calcium
Pregunta 36
Pregunta
A stimulus either causes an action potential or it doesn't. This is called
Pregunta 37
Pregunta
T tubules are invaginations of the
Respuesta
-
sarcoplasmic reticulum
-
sarcomere
-
myofibril
-
sarcoplasm
-
sarcolemma
Pregunta 38
Pregunta
The sarcoplasmic reticulum
Respuesta
-
stores calcium ions
-
shortens during muscle contraction
-
transmits nerve impulses to the myofibrils
-
connects adjacent sarcomeres
-
covers the muscle fiber
Pregunta 39
Pregunta
Whole muscles can respond in a graded fashion to stimuli by varying
Respuesta
-
the force of contraction of individual muscle fibers
-
the number of motor units recruited
-
the amplitude of the action potential
-
the frequency of stimulus
-
thresholds
Pregunta 40
Pregunta
In order for muscle relaxation to occur,
Respuesta
-
calcium ions must be transported to troponin
-
power strokes slow down
-
the active sites on actin must be blocked
-
sodium ions must be actively transported to troponin
-
the active sites on myosin must be uncovered
Pregunta 41
Pregunta
Which of the following will respond to a threshold stimulus with an all-or-none contraction?
Respuesta
-
a single muscle fiber
-
a single motor unit
-
a whole muscle
-
a single muscle fiber and a single motor unit
-
a single muscle fiber, a single motor unit, and a whole muscle
Pregunta 42
Pregunta
Which of the following is true?
Respuesta
-
the greater the overlap of actin and myosin, the stronger the contraction
-
overstretching a muscle will increase its tension
-
optimal actin and myosin overlap will produce maximal contraction
-
the greatest amount of tension is achieved when actin and myosin do not overlap
-
tension is great when actin and myosin overlap as much as they can
Pregunta 43
Pregunta
Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called:
Pregunta 44
Respuesta
-
provide nutrients to the muscle fiber
-
generate new muscle fibers
-
conduct action potentials deep into the muscle cell
-
release acetylcholine
-
store calcium ions
Pregunta 45
Pregunta
A myofilament is the
Respuesta
-
cell membrane of a muscle fiber
-
cytoplasm of muscle cells
-
structural and functional unit of the skeletal muscle cell
-
contractile threat that extends the length of the muscle fiber
-
protein strand composed of actin or myosin
Pregunta 46
Pregunta
Tendons that form thick flattened sheets are
Respuesta
-
ligaments
-
endoymysium
-
collagen fibers
-
aponeuroses
Pregunta 47
Pregunta
The expanded ends of sarcoplasmic reticulum are called
Respuesta
-
transverse tubules
-
triads
-
terminal cisternae
-
myoterminals
Pregunta 48
Pregunta
In a typical simple muscle, the