Question 1
Question
Thick filaments in skeletal muscle are composed of
Answer
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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
Question 2
Question
During isotonic contraction of a skeletal muscle fibre:
Answer
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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
Question 3
Question
In skeletal muscle calcium facilitates contraction by binding to:
Answer
-
tropomyosin
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actin
-
troponin
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myosin
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the thick filament
Question 4
Question
Motor unit’ refers to:
Answer
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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
Question 5
Question
During an isometric contraction of a skeletal muscle:
Answer
-
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
Question 6
Question
The cross bridge in the sacromere of skeletal muscle are made of:
Answer
-
actin
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myosin
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troponin
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tropomyosin
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myelin
Question 7
Question
With regard to knee jerk:
Answer
-
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
Question 8
Question
The most important contractile proteins are:
Answer
-
myosin
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troponin
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actin
-
tropomyosin
-
all of the above
Question 9
Question
Which role do Ca2+ ions play in the muscle contraction?
Question 10
Question
Smooth muscle is not cross striated because:
Answer
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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
Question 11
Question
lntercalated discs are most likely to be observed in:
Answer
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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
Question 12
Question
During strong exercise, oxygen consumption is greatest in the:
Answer
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brain
-
heart
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skeletal muscles
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liver
-
kidneys
Question 13
Question
An increase in force of a skeletal muscle contraction is initially achieved by:
Answer
-
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
Question 14
Question
Which area of the sacromere consists only of myosin filaments?
Answer
-
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
Question 15
Question
Which muscle cell compound stores oxygen?
Answer
-
creatine phosphate
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glycogen
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hemoglobin
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myoglobin
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lipid droplets
Question 16
Question
Smooth muscle is:
Answer
-
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
Question 17
Question
Skeletal muscle ls:
Question 18
Question
Cardiac muscle is:
Answer
-
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
Question 19
Question
Which type of muscle cell is multinucleated?
Answer
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Cardiac
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Smooth
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Skeletal
-
Cardiac and smooth
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None of the above
Question 20
Question
What is an example of a smooth muscle?
Answer
-
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)
Question 21
Question
How many actin filaments surround each myosin filament?
Question 22
Question
The muscular system is controlled by which system?
Question 23
Question
How many types of muscle are there?
Question 24
Question
The sacroplasmic reticulum stores:
Answer
-
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
Question 25
Question
Which of the following should affect the strength or force of skeletal muscle contraction?
Answer
-
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
-
concentration of Na+
Question 26
Question
Which of these is true of skeletal muscle:
Answer
-
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
Question 27
Question
Which of these is not a major property of muscle?
Answer
-
contractility
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elasticity
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excitability
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extensibility
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secretability
Question 28
Question
What is each myofibril made of?
Question 29
Question
Myosin myofilaments are
Answer
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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
-
attached to filaments that form the M-line
Question 30
Question
The part of the sacrolemma that invaginates into the interior of skeletal muscle fibers is the
Answer
-
T-tubule system
-
Sacroplasmic reticulum
-
Myofibrils
-
Terminal cisternae
-
Mitochondria
Question 31
Question
Which of these events occurs during the lag (latent) phase of muscle contraction?
Question 32
Question
Muscle contraction which cannot move weight because it is too heavy is:
Answer
-
isometric
-
isotonic
-
isokinetic
-
concentric
-
eccentric
Question 33
Question
Voluntary skeletal muscles in the leg are innervated
Answer
-
Postganglionic neurons
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Somatic motor neurons
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Preganglionic neurons
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CNS fibers
-
All the above
Question 34
Question
A small motor unit would control which type of movement?
Answer
-
fast but brief
-
intense and strong
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delicate and precise
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sprinting
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marathon running
Question 35
Question
Muscle fibers type 1 have only one of the following features:
Answer
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slow onset of contraction
-
easily fatigued
-
many enzyme for glycolysis
-
a slow refractory period
-
low mitochondrial content
Question 36
Question
Muscle fibers type Ila are:
Answer
-
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
Question 37
Question
Muscle fibers type IIb are:
Answer
-
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
Question 38
Question
Muscle fibers type 1 are
Answer
-
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
Question 39
Question
These bands of the sacromere do not shorten during contraction
Answer
-
A bands
-
H, I and M bands
-
Z discs and A bands
-
I bands
-
a and d
Question 40
Question
The role of transverse tubules in skeletal muscle fibers is to:
Answer
-
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
Question 41
Question
The cross bridges of the sarcomere in skeletal muscle are components of:
Answer
-
actin
-
myosin
-
troponin
-
tropomyosin
-
titin
Question 42
Question
The function of tropomyosin in skeletal muscle In
Answer
-
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
Question 43
Question
The cell membranes In skeletal muscle:
Answer
-
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
Question 44
Question
A skeletal muscle fibre at rest:
Answer
-
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
Question 45
Question
In skeletal muscle:
Answer
-
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
Question 46
Question
Visceral smooth muscle differs from skeletal muscle in that
Answer
-
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
Question 47
Question
A property shared by:
Answer
-
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
Question 48
Question
The action potential of skeletal muscle:
Answer
-
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
Question 49
Question
Smooth muscle need help of:
Answer
-
calmodulin for contraction
-
acetyl choline for contraction
-
K+ for contraction
-
monoamine oxidase for contraction
-
secondly molar for contraction