What effect did increasing the extracellular potassium have on the resting membrane potential?
answer
The resting membrane potential became less negative.
question
What effect did decreasing the extracellular sodium have on the resting membrane potential?
answer
Only a small change occurred, because the resting neuron is not very permeable to sodium.
question
The channels that provide for the movement of potassium in the resting neuron are _______.
answer
leakage
question
Establishing the resting membrane potential requires energy through the use of the _______.
answer
sodium-potassium pump
question
Which of the following was able to detect pressure?
answer
the Pacinian corpuscle and the free nerve ending
question
Which of the following does NOT describe graded potentials?
answer
They are always depolarizing.
question
Which of the following responded to a chemical stimulus?
answer
olfactory receptor
question
When the intensity of the appropriate stimulus was increased, the amplitude of the response _______.
answer
increased
question
The minimum voltage that is required to generate an action potential is called the _______.
answer
threshold voltage
question
Increasing the voltage resulted in which of the following?
answer
no change to the action potential
question
An axon that is more negative than the resting membrane potential is said to be _______.
answer
hyperpolarized
question
If an increase in extracellular potassium hyperpolarizes a neuron, which of the following would be correct?
answer
It would change the membrane potential to a more negative value.
question
Which of the following occurred in the presence of tetrodotoxin?
answer
The number of action potentials decreased.
question
Which of the following occurred in the presence of tetrodotoxin?
answer
An action potential was always seen at R1.
question
In the presence of lidocaine, the action potential was NOT affected at R1 because _______.
answer
lidocaine was applied downstream of R1
question
The effects of lidocaine and tetrodotoxin were _______.
answer
similar, but tetrodotoxin had a greater effect
question
Why does the threshold increase when the interval between the stimuli decreases?
answer
Some sodium channels have been inactivated and cannot be reopened immediately.
question
During the relative refractory period, _______.
answer
another action potential can be generated provided the stimulus is large enough.
question
When the interval between the stimuli decreases, _______.
answer
a second action potential is generated until the interval reaches the absolute refractory period
question
When the stimulus voltage is increased, _______.
answer
a greater-than-threshold depolarization results and sodium permeability into the cell increases to overcome the potassium exiting.
question
The time interval between action potentials is called the _______.
answer
interspike interval
question
Increase in stimulus intensity _______.
answer
increases the frequency of action potentials
question
The frequency of action potentials is _______.
answer
the reciprocal of the interspike interval, and measured in hertz
question
During the relative refractory period, _______.
answer
the stimulus must be above threshold to generate an action potential
question
Which fibers generate the smallest value for conduction velocity?
answer
C fibers
question
The time interval for conduction would be shortest with
answer
the largest and most heavily myelinated axons
question
Increasing the amount of myelination _______.
answer
decreases the time between action potentials
question
In this activity, the stimulus voltage used was _______.
answer
the same for all of the axons and suprathreshold for all of the axons
question
At a chemical synapse, the intensity of the stimulus is coded by _______.
answer
the amount of neurotransmitter released and the amount of calcium that enters the axon terminal
question
When the calcium was removed from the extracellular solution, _______.
answer
no neurotransmitter was released
question
When magnesium was added to the extracellular solution, _______.
answer
the amount of neurotransmitter released decreased
question
Calcium and magnesium are both _______.
answer
divalent cations
question
A weak, subthreshold stimulus will result in _______.
answer
a small depolarization at the receiving end of the neuron
question
Which stimulus was at or above threshold?
answer
the moderate and strong stimuli
question
Increasing the strength of the stimulus applied to the sensory receptor increased _______.
answer
the frequency of action potentials in the sensory neuron, the amount of neurotransmitter released at the axon terminal of the sensory neuron and the frequency of action potentials in the interneuron
question
An excitatory postsynaptic potential occurs _______.
answer
at the receiving end of the interneuron
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