The quantal nature of chemical synaptic transmission is BEST supported by observation of:
A. spontaneous mEPPs
B. discrete jumps in EPPs amplitude when Ca++ is normal
C. EPPs that vary smoothly in amplitude
D. a constant EPP amplitude
E. evoked EPPs smaller than mEPPs
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Question 2) Calcium entry into the presynaptic terminal will be greatest:
A. during the rising phase of the action potential
B. at the peak of the action potential
C. during the falling phase of the action potential
D. during the afterhyperpolarization following an action potential
E. when it is at its resting potential
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Question 3) Chemical synapses are characterized by:
A. unidirectional and instantaneous transmission of electrical signals
B. unidirectional transmission of electrical signals with a small delay
C. bidirectional and instantaneous transmission of electrical signals
D. bidirectional transmission of electrical signals with a small delay
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Question 4) Which of the following events is common to ALL types of sensory receptors?
A. the generation of a receptor potential
B. the generation of an action potential
C. the binding of a stimulus to a receptor
D. the binding of a stimulus to a membrane channel
E. membrane depolarization
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Question 5) Which of the following stimulus parameters is NOT encoded in the pattern of action potentials in a sensory axon?
A. threshold
B. frequency
C. modality
D. duration
E. intensity
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Question 6) At gap junctions, the intercellular space:
A. widens and is filled by electron-lucent material
B. widens and is filled by electron-dense material
C. narrows and is filled by electron-lucent material
D. narrows and is filled by electron-dense material
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Question 7) At electrical synapses:
A. there is a synaptic delay as the signal travels from the presynaptic to postsynaptic element
B. release of neurotransmitter is required
C. there is a low resistance pathway for current flow between cells
D. electrical potentials can be transmitted in only one direction
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Question 8) Which of the following is NOT a true statement about the conduction of action potentials in axons?
A. The inward Na+ current of an AP generates an AP in an adjacent portion of the axon.
B. All APs in a given axon are identical in magnitude and duration.
C. APs can be conducted in only one direction.
D. The velocity of AP conduction is positively correlated with axon diameter.
E. The frequency of APs is limited by the length of the refractory period.
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Question 9) The afterhyperpolarization that follows the action potential:
A. is due to the inactivation of voltage-gated Na+ channels
B. makes it easier to trigger another action potential
C. extends the relative refractory period
D. makes it impossible to fire another action potential
E. is the consequence of continuing K+ influx
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Question 10) At the threshold for generating an action potential:
A. the membrane is at the K+ equilibrium potential
B. the conductances for Na+ and K+ are equal
C. there is a rapid opening of voltage-gated Na+ channels
D. K+ conductance is maximal
E. the transmembrane voltage is zero
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