8535024
Descripción
Test por Med Student , actualizado hace más de 1 año
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Creado por Med Student
hace más de 7 años
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Pregunta 1
Pregunta
Thick filaments in skeletal muscle are composed of
Respuesta
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actin
-
myosin
-
troponin
-
calmodulin
-
tropomyosin
Pregunta 2
Pregunta
During isotonic contraction of a skeletal muscle fibre:
Respuesta
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The sarcomere shortens
-
A-bands shorten
-
Tension increases
-
Fibres relax
-
None of the above
Pregunta 3
Pregunta
In skeletal muscle calcium facilitates contraction by binding to:
Respuesta
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tropomyosin
-
actin
-
troponin
-
myosin
-
the thick filament
Pregunta 4
Pregunta
Motor unit’ refers to:
Respuesta
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a single motor neuron plus all the muscle fibres it innervates
-
a single muscle fibre plus all the motor neurons that innervate it
-
all of the motor neurons supplying a single muscle
-
a pair of antagonistic muscles
-
all of the muscles that affect the movement of any given joint
Pregunta 5
Pregunta
During an isometric contraction of a skeletal muscle:
Respuesta
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the I-bands shorten and the A-bands stay the same length
-
the thick and thin filaments slide past each other
-
sarcomere length does not change
-
tension does not change
-
none of the above
Pregunta 6
Pregunta
The cross bridge in the sacromere of skeletal muscle are made of:
Respuesta
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actin
-
myosin
-
troponin
-
tropomyosin
-
myelin
Pregunta 7
Pregunta
With regard to knee jerk:
Respuesta
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it is a monosynaptic reflex
-
the impulse travels via type Ca afferent fibres
-
the Golgi body is an important component
-
the stimulus begins in the tendon
-
it is a visceral reflex
Pregunta 8
Pregunta
The most important contractile proteins are:
Respuesta
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myosin
-
troponin
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actin
-
tropomyosin
-
all of the above
Pregunta 9
Pregunta
Which role do Ca2+ ions play in the muscle contraction?
Respuesta
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excitation-contraction coupling
-
prevent the contraction
-
form cross bridges
-
release energy for the contraction
-
excite the myofiber
Pregunta 10
Pregunta
Smooth muscle is not cross striated because:
Respuesta
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of myosin and actin in the myofibril
-
myofibrils are in register with each other
-
myofibrils are not in register with each other
-
it has gap junctions
-
it is surrounded by a basal lamina
Pregunta 11
Pregunta
lntercalated discs are most likely to be observed in:
Respuesta
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longitudinal section of skeletal muscle
-
transverse section of skeletal muscle
-
transverse section of cardiac muscle
-
longitudinal section of cardiac muscle
-
transverse section of smooth muscle
Pregunta 12
Pregunta
During strong exercise, oxygen consumption is greatest in the:
Respuesta
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brain
-
heart
-
skeletal muscles
-
liver
-
kidneys
Pregunta 13
Pregunta
An increase in force of a skeletal muscle contraction is initially achieved by:
Respuesta
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recruitment of nerve fibers
-
recruitment of muscle fibers
-
recruitment of motor units
-
increased intracellular calcium
-
increased lactic acid
Pregunta 14
Pregunta
Which area of the sacromere consists only of myosin filaments?
Respuesta
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I-bands
-
H-zone
-
A-bands
-
M-line
-
Z-disc
Pregunta 15
Pregunta
Which muscle cell compound stores oxygen?
Respuesta
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creatine phosphate
-
glycogen
-
hemoglobin
-
myoglobin
-
lipid droplets
Pregunta 16
Pregunta
Smooth muscle is:
Respuesta
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voluntary and spindle shaped
-
voluntary and striated
-
involuntary and spindle shaped
-
involuntary and striated
-
innervated by the somatic nervous system
Pregunta 17
Pregunta
Skeletal muscle ls:
Respuesta
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voluntary and spindle shaped
-
voluntary and striated
-
involuntary and spindle shaped
-
involuntary and striated
-
innervated by ANS
Pregunta 18
Pregunta
Cardiac muscle is:
Respuesta
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voluntary and spindle shaped
-
voluntary and striated
-
involuntary and spindle shaped
-
involuntary and striated
-
innervated by the somatic nervous system
Pregunta 19
Pregunta
Which type of muscle cell is multinucleated?
Respuesta
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Cardiac
-
Smooth
-
Skeletal
-
Cardiac and smooth
-
None of the above
Pregunta 20
Pregunta
What is an example of a smooth muscle?
Respuesta
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masseter (face)
-
bladder
-
heart
-
pronator teres (forearm)
-
rectus abdominis (belly)
Pregunta 21
Pregunta
How many actin filaments surround each myosin filament?
Respuesta
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two
-
four
-
six
-
eight
-
seven
Pregunta 22
Pregunta
The muscular system is controlled by which system?
Respuesta
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the cardiovascular system
-
the endocrine system
-
the nervous system
-
the respiratory system
-
the urinary system
Pregunta 23
Pregunta
How many types of muscle are there?
Respuesta
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two
-
three
-
four
-
five
-
six
Pregunta 24
Pregunta
The sacroplasmic reticulum stores:
Respuesta
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calcium ions
-
chloride ions
-
sodium ions
-
potassium ions
-
hydrogen ions
Pregunta 25
Pregunta
Which of the following should affect the strength or force of skeletal muscle contraction?
Respuesta
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the number of muscle fibers at rest
-
the degree of muscle stretch
-
the series-elastic elememts
-
stronger stimuli
-
concentration of Na+
Pregunta 26
Pregunta
Which of these is true of skeletal muscle:
Respuesta
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spindle-shaped cells
-
under involuntary control
-
many peripherally located nuclei per muscle fiber
-
forms the walls of hollow internal organs
-
may be autorhythmic
Pregunta 27
Pregunta
Which of these is not a major property of muscle?
Respuesta
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contractility
-
elasticity
-
excitability
-
extensibility
-
secretability
Pregunta 28
Pregunta
What is each myofibril made of?
Respuesta
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many muscle fibers
-
contains sacroplasmic reticulum
-
many sacromeres
-
contains T-tubules
-
is the same thing as a muscle fiber
Pregunta 29
Pregunta
Myosin myofilaments are
Respuesta
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attached to the Z-disk
-
found primarily in the I band
-
thinner than actin myofilaments
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absent from the H zone
-
attached to filaments that form the M-line
Pregunta 30
Pregunta
The part of the sacrolemma that invaginates into the interior of skeletal muscle fibers is the
Respuesta
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T-tubule system
-
Sacroplasmic reticulum
-
Myofibrils
-
Terminal cisternae
-
Mitochondria
Pregunta 31
Pregunta
Which of these events occurs during the lag (latent) phase of muscle contraction?
Respuesta
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Cross-bridge movement
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Active transport of Ca2+ into the sacroplasmic reticulum
-
Ca2+ binding to troponin
-
Sacromere shortening
-
Breakdown of ATP to ADP
Pregunta 32
Pregunta
Muscle contraction which cannot move weight because it is too heavy is:
Respuesta
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isometric
-
isotonic
-
isokinetic
-
concentric
-
eccentric
Pregunta 33
Pregunta
Voluntary skeletal muscles in the leg are innervated
Respuesta
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Postganglionic neurons
-
Somatic motor neurons
-
Preganglionic neurons
-
CNS fibers
-
All the above
Pregunta 34
Pregunta
A small motor unit would control which type of movement?
Respuesta
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fast but brief
-
intense and strong
-
delicate and precise
-
sprinting
-
marathon running
Pregunta 35
Pregunta
Muscle fibers type 1 have only one of the following features:
Respuesta
-
slow onset of contraction
-
easily fatigued
-
many enzyme for glycolysis
-
a slow refractory period
-
low mitochondrial content
Pregunta 36
Pregunta
Muscle fibers type Ila are:
Respuesta
-
slow-twitch, glycolytic, fatigable resistant
-
fast-twitch, oxidative-glycolytic, relatively fatigue resistant
-
fast-twitch, glycolytic, fatigable
-
slow-twitch, oxidative, fatigue resistant
-
fast-twitch, oxidative, fatigable
Pregunta 37
Pregunta
Muscle fibers type IIb are:
Respuesta
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slow-twitch, glycolytic, fatigable resistant
-
fast-twitch, oxidative-glycolytic, relatively fatigue resistant
-
fast-twitch, glycolytic, fatigable
-
slow-twitch, oxidative, fatigue resistant
-
fast-twitch, oxidative, fatigable
Pregunta 38
Pregunta
Muscle fibers type 1 are
Respuesta
-
slow-twitch, glycolytic, fatigable resistant
-
fast-twitch, oxidative-glycolytic, relatively fatigue resistant
-
fast-twitch, glycolytic, fatigable
-
slow-twitch, oxidative, fatigue resistant
-
fast-twitch, oxidative, fatigable
Pregunta 39
Pregunta
These bands of the sacromere do not shorten during contraction
Respuesta
-
A bands
-
H, I and M bands
-
Z discs and A bands
-
I bands
-
a and d
Pregunta 40
Pregunta
The role of transverse tubules in skeletal muscle fibers is to:
Respuesta
-
connect the sacromeres to each other
-
bind the myofibrils
-
spread the action potential quickly
-
connect the sacrolemma to the sacroplasmic reticulum
-
bind to the receptors- dihydropyridine receptors
Pregunta 41
Pregunta
The cross bridges of the sarcomere in skeletal muscle are components of:
Respuesta
-
actin
-
myosin
-
troponin
-
tropomyosin
-
titin
Pregunta 42
Pregunta
The function of tropomyosin in skeletal muscle In
Respuesta
-
sliding on actin to produce shortening
-
releasing Ca2+ after initiation of contraction
-
binding to myosin during contraction
-
covering up the actin binding sites of myosin at rest
-
releasing Na+ after contraction
Pregunta 43
Pregunta
The cell membranes In skeletal muscle:
Respuesta
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are impermeable to fat-soluble substances
-
are more permeable to sodium than to potassium ions
-
become more permeable to glucose in the presence of insulin
-
become less permeable to potassium in the presence of insulin
-
are ligand dependent
Pregunta 44
Pregunta
A skeletal muscle fibre at rest:
Respuesta
-
presents with a membrane which is positively charged on the inside with respect to the outside
-
contains intracellular stores of calcium ions
-
is normally innervated by more than one motor neuron
-
becomes more excitable as its resting membrane potential increase in absolute value
-
becomes less excitable as the extracellular ionized calcium levels fall
Pregunta 45
Pregunta
In skeletal muscle:
Respuesta
-
contraction occurs when its pacemaker cells depolarize sufficiently to reach the threshold for firing
-
calcium is taken up by the sarcotubular system when it contracts
-
actin and myosin filaments shorten when it contracts
-
the sarcomeres shorten during contraction
-
contraction strength is related to the influx of K+ ions
Pregunta 46
Pregunta
Visceral smooth muscle differs from skeletal muscle in that
Respuesta
-
it contracts when stretched
-
it is not paralyzed when its motor nerve supply is cut
-
its cells have unstable resting membrane potentials
-
excitation depends more on influx of extracellular calcium than release of calcium from endoplasmic reticulum
-
all of the above
Pregunta 47
Pregunta
A property shared by:
Respuesta
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skeletal and cardiac muscles is their striated microscopical appearance
-
cardiac and visceral smooth muscles is their spontaneous activity when denervated
-
skeletal and cardiac ventricular muscles is their stable resting membrane potential
-
all types of muscles is that contraction strength is related to their initial length
-
all of the above
Pregunta 48
Pregunta
The action potential of skeletal muscle:
Respuesta
-
has a prolonged plateau phase
-
spreads inwards to all parts of the muscle via T tubules
-
is longer than the action potential of cardiac muscle
-
is not essential for muscle conduction
-
has different amplitudes
Pregunta 49
Pregunta
Smooth muscle need help of:
Respuesta
-
calmodulin for contraction
-
acetyl choline for contraction
-
K+ for contraction
-
monoamine oxidase for contraction
-
secondly molar for contraction
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