Which of the following structures does not conduct an action potential?
sarcolemma
T-tubule
Axolemma
Axon
Dendrite
Dendrite
Which structure contains ATPase?
thin filament
thick filament
triad
M-line
Thick Filament
When a nerve impulse arrives at the axon terminal of a nerve:
the axon terminal become more permeable to calcium
the axon terminal becomes more permeable to sodium
the axon terminal become more permeable to potassium
all of the above would occur
the axon terminal become more permeable to calcium
If voltage gated potassium channels open on the sarcolemma, the skeletal muscle is undergoing:
depolarization
hyperpolarization
repolarization
repolarization
Which event allows the thick filament to pull the thin filament toward the M-line of the sarcomere?
cross bridge detachment
cross bridge formation
power stroke
cocking of myosin head
Power Stroke
During which phase of a muscle twitch would an action potential be propagated down the T-tubules of a skeletal muscle?
latent period
period of contraction
period of relaxation
latent period
As the frequency of action potentials down the a motor nerve increases the amount of neurotransmitter released into the synaptic cleft would:
increase
decrease
be unaffected
Increase
During an event such as incomplete tenanus:
there are brief periods in which calcium is being pumped back into the SR
there are no periods in which calcium is being pumped back into the SR
the motor nerve must be releasing ACh in periodic bursts
the motor nerve must be releasing ACh constantly over a brief period of time
answers A and C are correct
answers A and C are correct
Which pathway generates the most energy for muscle contractions?
aerobic pathway
anaerobic pathway
direct phosphorylation
aerobic pathway
Which substrate results from the immediate decomposition of glucose in the presence of oxygen?
lactic acid
water
pyruvic acid
ATP
pyruvic acid
Which type of muscle has the ability to contract when it is subject to a stretch that is twice its resting length?
skeletal muscle
smooth muscle
cardiac muscle
smooth muscle
When the postsynaptic neuron becomes more negative this event is called:
an IPSP
an EPSP
a resting potential
an action potential
an IPSP
An action potential is an all-or-none event
true
false
True
Action potentials that result from very strong stimuli are_____those which result from weaker stimuli.
greater in strength than
smaller in strength that
of the same strength as
of the same strength as
A somatic efferent neuron is one which?
conducts motor impulses to skeletal muscle
conducts sensory impulses from skeletal muscle
conducts motor impulses to smooth or cardiac muscle or glands
conducts sensory impulses from smooth or cardiac muscle or glands
either B or D is correct
conducts motor impulses to skeletal muscle
How does an increase in the concentration of Na+ in the intracellular fluid affect a resting membrane potential?
the membrane will depolarization, so AP is more likely
the membrane will hyperpolarization, so AP is less likely
the membrane will depolarization, so AP is more likely
In an EPSP, the membrane potential of the post-synaptic neuron is_____ the resting potential.
more negative than
less negative than
the same as
less negative than
With one exception, each of these is accurate regarding graded potentials.
Identify the exception.
short-lived
increase in amplitude as they move away from the point of stimulation
can occur on receptor endings
involve a change in potential difference from resting level
results from the opening and closing of chemically gated channels
increase in amplitude as they move away from the point of stimulation
With one exception, all of the following occur during depolarization. Which does not?
membrane permeability to Na+ increases
Na+ moves into the cell along a steep concentration gradient
the outside of the cell membrane becomes increasingly positive
the rate of sodium movement into the cell increases
the outside of the cell membrane becomes increasingly positive
Schwann cells are found in the?
CNS only
PNS only
CNS and PNS
PNS only
The most abundant source of stored energy in a muscle is
cellular ADP
creatine phosphate
cellular ATP
creatine
glycogen
glycogen
Which one of these muscles would possess the fewest muscle fibers per motor unit?
Muscles of facial expression
Trapezius
Pectoralis major
Muscles of facial expression
With one exception, each of the following is a usual result of exercise. Which is not?
Increase in number of mitochondria
Increase in the number of capillaries surrounding the muscle fibers
Increase in the amount of stored glycogen
All of the above typically occur as a result of exercise
All of the above typically occur as a result of exercise
Which of the following is correct?
Tension increases during isometric contraction and the muscle shortens
Muscle length and tension remain constant during isotonic contraction
Myofilaments are sliding during isotonic contraction
Myofilaments are sliding during isotonic contraction
Which intracellular molecule is used to quickly generate ATP when skeletal muscle suddenly becomes very active?
Oxygen
Creatine phosphate
Myosin
Troponin
Creatine phosphate
Based only on an electrical gradient, sodium ions should:
enter the resting cell
leave the resting cell
not cross the resting cell membrane
enter the resting cell
A change in membrane potential from resting to a more negative voltage
is a depolarization
is often due to sodium entry into the cell
leaves the membrane less responsive to stimulation
all of the above are correct
leaves the membrane less responsive to stimulation
If a stimulus that is significantly stronger than threshold is applied to the membrane of an excitable cell during its relative refractory period, what will likely occur?
the membrane will not respond
the membrane will hyperpolarize
the membrane will depolarize
the membrane will depolarize
If the ECF concentration of sodium increased, the rate of sodium diffusion across the membrane would:
increase
decrease
not change
increase
Synaptic transmission at the neuromuscular junction involves the neurotransmitter _____ and results in _________.
dopamine…excitation
norepinephrine…hyperpolarization
acetylcholine…hyperpolarization
norepinephrine…depolarization
acetylcholine…depolarization
acetylcholine…depolarization
Which of the following membrane potentials represents hyperpolarization in a typical nerve cell?
-70 mV
0 mV
-90 mV
+40 mV
both A and C
-90mV
In an EPSP, the membrane potential of the post-synaptic neuron is_____ the resting potential.
more negative than
less negative than
the same as
less negative than
Which of the following will increase the speed of nerve impulse transmission?
salutatory conduction
larger axon diameter
less myelination
all of the above
answers A and B are correct
answers A and B are correct
Which of the following comprise the thin myofilament?
Myosin molecules
Actin and myosin
Actin, tropomyosin and troponin
Tropomyosin and troponin
Actin, tropomyosin and troponin
Which of the following affect(s) the strength or force of skeletal muscle contraction?
The number of muscle fibers contracting
The degree of muscle stretch
The relative size of the muscle
All of the above
