PhysioEx Exercise 3 quiz Questions and Answers Already Passed Graded A+
What is the approximate concentration of K+ inside a typical cell? - Answers 150mM
What is the approximate concentration of Na+ inside a cell? - Answers 5mM
What is the approximate concentration of Na+ outside a cell? - Answers 150mM
What is the approximate concentration of K+ outside a typical cell? - Answers 5mM
A negative membrane potential was recorded when the tip of the microelectrode was - Answers both
inside the cell body and inside the axon
Which of the following caused a change in membrane potential from -70 to -40 in the cell body? -
Answers an increase in extracellular K+
Which of the following has the most negative voltage? - Answers between the inside of the axon and the
outside of the axon with control K+ ECF
Assuming the resting potential of a sensory neuron is -70mV, which of the following represents a
depolarization? - Answers change to -60mV
Which of the following is a sensory modality? - Answers all of the above (touch, smell, sight, & paint)
which of the following is a sensory stimulus? - Answers all of the above ( pressure, chemical odorants &
light)
Which of the following is true of the response of a sensory neuron to the appropriate sensory stimulus?
- Answers it can be a receptor potential & it is a graded potential AND it is a change in the resting
membrane potential
A very intense stimulus can sometimes stimulate sensory neurons that have evolved for a different
modality. Thus, with a blow to the eye, one "sees stars". In this example, the photoreceptors in the eye
are responding to - Answers intense pressure
Olfactory receptor neurons respond to low concentrations of chemical odorants because there are
membrane proteins in the receptor ending of this sensory neuron that - Answers can bind and respond
to the specific odorant
The sequence of events starting with a sensory stimulus and ending with a change in membrane
potential is called - Answers sensory transduction
Starting at a resting membrane potential of -70mV a change to which of the following represents the
largest receptor potential? - Answers a change to -50mV
Axons are - Answers long, thin structure that extend from a neuronal cell body
which of the following is easier? - Answers extracellular recordings of action potential
, An action potential is usually initiated in an axon at or near - Answers all of the above (the axon hillock,
the initial segment, or the trigger zone)
The initiation of an action potential in a sensory neuron in the body normally - Answers follows a
sufficiently large depolarizing receptor potential
The threshold voltage in an axon is usually - Answers less negative than the resting membrane potential
If a graded receptor potential made the resting potential of the axon more negative (for example, -70mV
changes to -75mV) you would expect - Answers it to be more difficult for this axon to reach the
threshold voltage
Failure to reach the threshold voltage in the axon of a sensory neuron could be caused by - Answers all
of the above (generation of a receptor potential that makes the axonal resting membrane potential
more negative, an insufficient depolarizing receptor potential, AND application of the wrong stimulus
modality)
Voltage-gated Na+ channels are membrane channels that open - Answers when the membrane
depolarizes
When open, Na+ channels allow - Answers Na+ ions to diffuse into the cell
Which of the following is true of an action potential? - Answers all of these answers are correct ( the
generation of an action potential uses voltage-gated Na+ channels, an action potential is generated
when the membrane potential reaches threshold, AND an action potential is a large, all or none change
in membrane potential)
Which of the following can reduce the likelihood of an action potential? - Answers All of these can
reduce the likelihood of an action potential (TTX, lidocaine, increasing the leak of K+ from a cell)
In the control, the amplitude of the action potentials at R1 and R2 are the same. Which of the following
explains this? - Answers All these are reasonable explanations ( there are voltage-gated Na+ channels all
along the axon, the action potential is an all-or-none event, Action potentials propagate or remake
themselves at each point along the axon)
Blocking the voltage-gated Na+ channels between R1 and R2 with TTX blocks - Answers The propagation
of the action potential from R1 and R2
When voltage-gated Na+ channels between R1 and R2 are blocked with TTX, an action potential is still
recorded at R1 because - Answers The voltage-gated Na+ channels between the stimulus and R1 are
unaffected by the TTX
Puffer fish must be prepared carefully and properly before they can be eaten. Eating puffer fish can
cause numbness of the lips, probably because - Answers action potentials from sensory neurons in the
lips are blocked
What is the approximate concentration of K+ inside a typical cell? - Answers 150mM
What is the approximate concentration of Na+ inside a cell? - Answers 5mM
What is the approximate concentration of Na+ outside a cell? - Answers 150mM
What is the approximate concentration of K+ outside a typical cell? - Answers 5mM
A negative membrane potential was recorded when the tip of the microelectrode was - Answers both
inside the cell body and inside the axon
Which of the following caused a change in membrane potential from -70 to -40 in the cell body? -
Answers an increase in extracellular K+
Which of the following has the most negative voltage? - Answers between the inside of the axon and the
outside of the axon with control K+ ECF
Assuming the resting potential of a sensory neuron is -70mV, which of the following represents a
depolarization? - Answers change to -60mV
Which of the following is a sensory modality? - Answers all of the above (touch, smell, sight, & paint)
which of the following is a sensory stimulus? - Answers all of the above ( pressure, chemical odorants &
light)
Which of the following is true of the response of a sensory neuron to the appropriate sensory stimulus?
- Answers it can be a receptor potential & it is a graded potential AND it is a change in the resting
membrane potential
A very intense stimulus can sometimes stimulate sensory neurons that have evolved for a different
modality. Thus, with a blow to the eye, one "sees stars". In this example, the photoreceptors in the eye
are responding to - Answers intense pressure
Olfactory receptor neurons respond to low concentrations of chemical odorants because there are
membrane proteins in the receptor ending of this sensory neuron that - Answers can bind and respond
to the specific odorant
The sequence of events starting with a sensory stimulus and ending with a change in membrane
potential is called - Answers sensory transduction
Starting at a resting membrane potential of -70mV a change to which of the following represents the
largest receptor potential? - Answers a change to -50mV
Axons are - Answers long, thin structure that extend from a neuronal cell body
which of the following is easier? - Answers extracellular recordings of action potential
, An action potential is usually initiated in an axon at or near - Answers all of the above (the axon hillock,
the initial segment, or the trigger zone)
The initiation of an action potential in a sensory neuron in the body normally - Answers follows a
sufficiently large depolarizing receptor potential
The threshold voltage in an axon is usually - Answers less negative than the resting membrane potential
If a graded receptor potential made the resting potential of the axon more negative (for example, -70mV
changes to -75mV) you would expect - Answers it to be more difficult for this axon to reach the
threshold voltage
Failure to reach the threshold voltage in the axon of a sensory neuron could be caused by - Answers all
of the above (generation of a receptor potential that makes the axonal resting membrane potential
more negative, an insufficient depolarizing receptor potential, AND application of the wrong stimulus
modality)
Voltage-gated Na+ channels are membrane channels that open - Answers when the membrane
depolarizes
When open, Na+ channels allow - Answers Na+ ions to diffuse into the cell
Which of the following is true of an action potential? - Answers all of these answers are correct ( the
generation of an action potential uses voltage-gated Na+ channels, an action potential is generated
when the membrane potential reaches threshold, AND an action potential is a large, all or none change
in membrane potential)
Which of the following can reduce the likelihood of an action potential? - Answers All of these can
reduce the likelihood of an action potential (TTX, lidocaine, increasing the leak of K+ from a cell)
In the control, the amplitude of the action potentials at R1 and R2 are the same. Which of the following
explains this? - Answers All these are reasonable explanations ( there are voltage-gated Na+ channels all
along the axon, the action potential is an all-or-none event, Action potentials propagate or remake
themselves at each point along the axon)
Blocking the voltage-gated Na+ channels between R1 and R2 with TTX blocks - Answers The propagation
of the action potential from R1 and R2
When voltage-gated Na+ channels between R1 and R2 are blocked with TTX, an action potential is still
recorded at R1 because - Answers The voltage-gated Na+ channels between the stimulus and R1 are
unaffected by the TTX
Puffer fish must be prepared carefully and properly before they can be eaten. Eating puffer fish can
cause numbness of the lips, probably because - Answers action potentials from sensory neurons in the
lips are blocked
