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