physiology & anatomy chapter 9 practice exam
tetanus of muscles is described as
action potential frequency is high enough that no relaxation of muscle fibers occurs
a lack of mitochondria within skeletal muscle fibers would impair which ATP-yielding chemical process
aerobic respiration
when skeletal muscle is producing CO, and water while making ATP, which chemical processes could be active at this time
aerobic respiration
smooth muscle and cardiac muscle are similar in that they both
are under involuntary control
how many ATP (i.e., the net gain) are generated in the reactions converting glucose to lactic acid?
2
at the neuromuscular junction, chemical transmitters diffuse across a microscopic gap called the:
synapse
these invaginations of the plasma membrane in smooth muscle are thought to function similar to both the SR and T tubule of skeletal muscle:
terminal cisternae
a sustained muscle contraction is known as
tetanus
which of the following events occurs during the lag phase of a muscle twitch
the action potential is propagated from presynaptic to postsynaptic membrane
this component of the actin myofilament consists of two strands that spiral about the actin core and help to stiffen the molecule. In addition it serves to block the myosin binding sites on the actin molecule:
tropomyosin
which of these terms might best indicate the size of a muscle:
vastus
during resting conditions,_ is synthesized to store energy
creatine phosphate
during resting conditions,___is synthesized to store energy.
creatine phosphate
sarcoplasm is the
cytoplasm of a muscle fiber
which of the following conditions in muscle fibers would contribute to muscle fatigue
depletion of ATP reserves
the specialized junctions/contacts that are responsible for electrical synapses are called
gap junctions
which of the following is part of a thin myofilament
globular (G) actin
troponin
has a calcium-binding site.
the role of ionic calcium in cross bridge attachment is:
none of the above
a sarcomere extends from
one Z disk to an adjacent Z disk
the end of the muscle attached to the less moveable bone is the
origin
when repolarization of the plasma membrane is complete, the
original polarity of the cell is restored
a skeletal muscle generates the greatest tension when it is
partially stretched before being stimulated
muscles exhibit the property of excitability. this means that the muscle
responds to stimulation by the nervous system
the signal for release of calcium from the terminal cisternae
results from depolaization of the T tubule
in the structure called a triad, the T tubule is sandwiched between:
sacs of sarcoplasmic reticulum
T tubules are invaginations of the
sarcolemma
in order for excitation-contraction coupling to occur, the production of an action potential must occur within the__of a muscle fiber.
sarcolemma
the plasma membrane of a muscle fiber is called
sarcolemma
these muscle fibers have slow acting myosin ATPases and are best suited for endurance activities
slow oxidative fibers
in the case of the sodium-potassium pump:
- ATP is required - both ions are moved against their respective concentration gradient
during a muscle fiber contraction, which of the following decreases in size? check all that apply.
- H zone - I band - entire sarcomere
which of the following describes titin's roles in muscle contraction? (Check all that apply.)
- accounts for muscle's excitability - accounts for muscle's extensibility and elasticity
which type of muscle is autorhythmic
- cardiac - smooth
electrical synapses may be found in
- cardiac muscle - smooth muscle
spontaneous depolarization would most likely be seen in:
- cardiac muscle - visceral smooth muscle
ionic calcium
- promokes neurotransmitter release from the axonal terminal - binds with TC of the troponin complexto trigger the sliding of myofilaments and ATPase activity
in order to stop the stimulation of the post-synaptic membrane, neurotransmitter must be removed from the synapse. this is accomplished by:
- reuptake of the neurotransmitter by the presynaptic terminal - degradation by enzymes such as acetylcholinesterase
during muscle contraction
- the I band shorten - the thick and thin filaments actually slide over each other - the distance between the Z discs (lines) decreases
arrange the following list of biochemical events in the correct sequence: (1) an action potential is conducted deep into the muscle fiber by the T tubule. (2) calcium ions bind to troponin. (3) the membranes of the sarcoplasmic reticulum become more permeable to calcium ions. (4) calcium ions diffuse into the sarcoplasm around the myofibril. (5) the troponin-tropomyosin complex moves exposing active sites.
1, 3, 4, 2, 5
the region of the sarcomere that contains both actin and myosin myofilaments is called the
A band
as demonstrated by rigor mortis, this molecule is essential for the myosin cross bridge tc detach:
ATP
during the contraction phase of a muscle twitch,
actin-myosin cross-bridges form
what is a triad
a T tubule and two adjacent terminal cisternae
a isometric contraction is described as
a muscle produces an increasing tension as the length remains constant
an eccentric contraction is described as
a muscle produces tension, but the length of the muscle is increasing
what is tropomyosin
a protein found along the groove of the F-actin double helix
in the presence of oxygen, the pyruvic acid is generated in glycolysis:
accepts hydrogen from NADH and is thereby reduced to lactic acid
synaptic vesicles in the neuromuscular junction contain
acetylcholine
the active sites to which cross-bridges attach are found on the
actin myofilaments
visceral smooth muscle
all of the choices are correct
treppe
all of these choices are correct
neostigmine
an acetylcholinesterase inhibitor
a stimulus either causes an action potential or it doesn't. this is called
an all-or-none response
which metabolic pathway do skeletal muscles rely on when someone is lifting weights
anaerobic respiration
which type of respiration rapidly produces ATP for short time periods
anaerobic respiration
a fascicle
is surrounded by perimysium
which of the following statements regarding the sliding filament model is false
both actin and myosin myofilaments shorten during contraction
which type of muscle tissue is autorhythmic
both cardiac and smooth muscle
acetylcholinesterase (AChE)
breaks down acetylcholine in the synaptic space
when an action potential reaches the presynaptic terminal
calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels
which type of muscle tissue has cells that branch
cardiac muscle
diffusion of acetylcholine across the neuromuscular junction
causes depolarization of the sarcolemma
the chief extracellular anion in the cell's environment is:
chloride
muscle myofibrils
contain myosin and actin myofilaments
actin myofilaments
contain strands of fibrous actin
lack of acetylcholinesterase in the synaptic cleft would result in
continuous stimulation of the postsynaptic membrane
the capacity of a muscle cell to shorten forcefully is known as
contractility
in this portion of the myogram associated with the twitch response, excitation-contraction coupling is occurring
contraction
if Na+ cannot enter a muscle fiber in response to a stimulus,
contraction cannot occur
in terms of the layers of smooth muscle lining the digestive tract, contraction of the longitudinal layer:
dilates the organ and shortens it
individual skeletal muscle fibers are covered by delicate connective tissue membrane called the
endomysium
which of the following connective tissue layers is outside all the others
epimysium
which of the following is true about skeletal muscle
every muscle fiber receives a branch of an axon from the nerve
acetylcholine is released from the presynaptic terminal by the process of
exocytosis
muscle fibers are grouped into bundles which are called
fascicles
assume an individual has hyperkalemia. what does this do the resting membrane potential
hyperpolarizes the cell making it less irritable
curare blocks acetylcholine receptors at the motor end plate. this would result in
inability of the muscle fiber to respond to nervous stimulation
in muscle, the so-called "H zone"
is visible only in relaxed fibers
a sarcomere will generate a more forceful contraction if:
it is slightly stretched
a by-product of anaerobic respiration in muscle fibers is
lactate
the time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase
latent or lag
skeletal muscle develops from cells called
myoblasts
bundles fine fibers that extend lengthwise along muscle fibers are called
myofibrils
muscle cells have the ability to store their own oxygen by combining this gas with
myoglobin
this molecule is most likely to exhibit ATP binding sites and ATPase
myosin
ATPhase is found in
myosin heads
at rest, the inside of the sarcolemma is relative to the outside
negatively charged
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
neuromuscular junctions
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
neuromuscular junctions
which of the following is true during the resting membrane potential
potassium is concentrated primarily inside the cell
when the myosin head flexes into a bend, pulling the actin filament along with it, this is called the
power stroke
in terms of the two layers of muscle lining the digestive tract, contraction of the longitudinal layer:
shortens and dilates the organs
which type of muscle tissue is multinucleated
skeletal muscle
which type of muscle tissue is multinucleated?
skeletal muscle
which type of muscle tissue would cause flexion and extension of the arm
skeletal muscle
the model that describes the contraction of the muscle is called the
sliding filament model
force of contraction produced by a muscle can be increased by
summation
muscles involved in precise movements would be more likely to have
small motor units
which type of muscle tissue causes vasoconstriction
smooth muscle
which type of muscle tissue has spindle-shaped cells
smooth muscle
which of the following would be characterized as multiunit smooth muscle:
smooth muscle of the iris and the arrector pili muscles
the chief extracellular cation in a typical cell's environment is
sodium
depolarization of the plasma membrane occurs when there is a rapid influx (inflow) of rev:
sodium ions
the sarcoplasmic reticulum
stores calcium
a sarcomere is the
structural and functional unit of the skeletal muscle fiber
oxygen deficit represents
the amount of O2 that cells need to replenish ATP supplies after exercise
the type of muscle fatigue known as "psychological fatigue" is the result of
the emotional state of an individual
skeletal muscles contract with varying degrees of strength at different times. this is referred to as:
the graded strength principle
concentric contractions occur when
the muscle produces increasing tension as it shortens
when comparing smooth and skeletal muscle cells, which of the following statements is true
the myofilaments in smooth muscle do not form sarcomeres
whole muscles can respond in a graded fashion to stimuli by varying
the number of motor units recruited
the "external oblique" muscle is most likely named on the basis of
the orientation of the muscle's fibers
the active transport mechanism is responsible for maintaining resting membrane potential in cells:
the sodium potassium pump
this active transport mechanism is responsible for maintaining resting membrane potential in cells
the sodium potassium pump
the refractory period
the time during which the tissue cannot respond again
the plasma membrane of an excitable cell is more permeable to K+ because
there are more leak ion channels for K+ than Na+.
what is the role of pacemaker cells
they rapidly develop action potentials
which of the following statements concerning fast-twitch muscle fibers is true
they split ATP rapidly
which of the following is composed of myosin molecules
thick myofilaments
channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called
voltage-gated ion channels
aerobic respiration
yields as many as 36 ATP per glucose molecule metabolized
