PNB 2264 EXAM 2 QUESTIONS AND
ANSWERS ALL CORRECT
The length of the sarcomeres in resting muscles affects:
the magnitude of the stimulus.
the tension developed during a twitch.
whether a muscle will fatigue.
the ability to maintain a prolonged contraction. - Answer- the tension developed during a
twitch.
During the depolarization phase of the action potential, _____________ .
Voltage-gated Na+ channels are open
A positive feedback cycle dramatically increases permeability to K+
K+ leak channels close
Membrane potential is moving toward threshold - Answer- Voltage-gated Na+ channels
are open
A closer look at the muscle fiber subtypes in skeletal muscles responsible for supporting
posture vs. those used for sprinting would likely reveal:
An increased number of type IIb fibers & more myoglobin
An increased number of type IIb fibers and less myoglobin
An increased number of IIa fibers & more myoglobin
An increased number of type I fibers & more myoglobin - Answer- An increased number
of type I fibers & more myoglobin
UNLIKE graded potentials, action potentials ____________ .
Occur in muscle cells
Are changes in membrane potential
Involve depolarization
Measure the same amplitude at the stimulus site as they do further away from the
stimulus site - Answer- Measure the same amplitude at the stimulus site as they do
further away from the stimulus site
Which of the following is TRUE of the power stroke?
It results in the depolarization of voltage gated sodium channels
, It places myosin in a high-energy conformation
It occurs only in smooth muscle
It occurs while ADP is bound to Myosin - Answer- It occurs while ADP is bound to
Myosin
__________ is made of multiple globular molecules polymerized to form long chains or
filaments.
Myosin
Titin
Actin
Troponin
Tropomyosin - Answer- Actin
The parallel conductance equation is used to predict _____________.
Membrane potential at rest
Equilibrium potential of just one ion at rest
Conductance for an ion during an action potential
Concentration of Na+ inside and outside the neuron - Answer- Membrane potential at
rest
Consider a living neuron (that is, a real cell and not an artificial membrane) and assume
equilibrium potential for Na+ is +55 mV. If we now open more and more Na+ channels,
then membrane potential will ________________ +55mV.
Become more negative (less than)
Get closer and closer to
Eventually reach
Get more and more positive (greater than) - Answer- Get closer and closer to
Which of the following are found in the dorsal root ganglia of the spinal cord?
Cell bodies of primary afferent (sensory) neurons
Cell bodies of alpha motor neurons
Synapses between primary afferent and motor neurons
All of the above - Answer- Cell bodies of primary afferent (sensory) neurons
Sensory transduction is the process of converting ___________ .
Stimulus energy from one modality (such as touch) into another modality (such as pain.)
Stimulus energy into a change in membrane potential
Graded potentials into action potentials
All of the above - Answer- Stimulus energy into a change in membrane potential
Increased intensity of a pressure stimulus (applied to the same spot on your finger) is
coded by ______ .
ANSWERS ALL CORRECT
The length of the sarcomeres in resting muscles affects:
the magnitude of the stimulus.
the tension developed during a twitch.
whether a muscle will fatigue.
the ability to maintain a prolonged contraction. - Answer- the tension developed during a
twitch.
During the depolarization phase of the action potential, _____________ .
Voltage-gated Na+ channels are open
A positive feedback cycle dramatically increases permeability to K+
K+ leak channels close
Membrane potential is moving toward threshold - Answer- Voltage-gated Na+ channels
are open
A closer look at the muscle fiber subtypes in skeletal muscles responsible for supporting
posture vs. those used for sprinting would likely reveal:
An increased number of type IIb fibers & more myoglobin
An increased number of type IIb fibers and less myoglobin
An increased number of IIa fibers & more myoglobin
An increased number of type I fibers & more myoglobin - Answer- An increased number
of type I fibers & more myoglobin
UNLIKE graded potentials, action potentials ____________ .
Occur in muscle cells
Are changes in membrane potential
Involve depolarization
Measure the same amplitude at the stimulus site as they do further away from the
stimulus site - Answer- Measure the same amplitude at the stimulus site as they do
further away from the stimulus site
Which of the following is TRUE of the power stroke?
It results in the depolarization of voltage gated sodium channels
, It places myosin in a high-energy conformation
It occurs only in smooth muscle
It occurs while ADP is bound to Myosin - Answer- It occurs while ADP is bound to
Myosin
__________ is made of multiple globular molecules polymerized to form long chains or
filaments.
Myosin
Titin
Actin
Troponin
Tropomyosin - Answer- Actin
The parallel conductance equation is used to predict _____________.
Membrane potential at rest
Equilibrium potential of just one ion at rest
Conductance for an ion during an action potential
Concentration of Na+ inside and outside the neuron - Answer- Membrane potential at
rest
Consider a living neuron (that is, a real cell and not an artificial membrane) and assume
equilibrium potential for Na+ is +55 mV. If we now open more and more Na+ channels,
then membrane potential will ________________ +55mV.
Become more negative (less than)
Get closer and closer to
Eventually reach
Get more and more positive (greater than) - Answer- Get closer and closer to
Which of the following are found in the dorsal root ganglia of the spinal cord?
Cell bodies of primary afferent (sensory) neurons
Cell bodies of alpha motor neurons
Synapses between primary afferent and motor neurons
All of the above - Answer- Cell bodies of primary afferent (sensory) neurons
Sensory transduction is the process of converting ___________ .
Stimulus energy from one modality (such as touch) into another modality (such as pain.)
Stimulus energy into a change in membrane potential
Graded potentials into action potentials
All of the above - Answer- Stimulus energy into a change in membrane potential
Increased intensity of a pressure stimulus (applied to the same spot on your finger) is
coded by ______ .
