Quiz questions Flashcards
Is equilibrium potential affected by only ions inside the cell, both inside and outside or just inside?
Only inside
Is membrane potential affected by only ions inside the cell, both inside and outside or just inside?
Both inside and outside
What is the major determinant of the permeability of a membrane to a specific ion?
Number of open ion channels for that specific ion
When does an action potential occur?
When the cellls membrane potential reaches threshold
Are nerve cells capable of conducting electricity?
No
Hodgkin and Katz proposed that sodium was the predominant ion associated with the firing of an action potential because…?
The membrane potential approaches the Na+ potential during the rising phase
Studies of the ionic basis of the action potential in squid giant axon found that …?
Decreasing sodium outside the cell decreases the size of the action potential
The squid giant Axon is useful in neuronal studies because…?
The cytoplasm in the axon can be extruded, thus allowing studies of its composition
How does the resting membrane potential of a typical neuronal compare to the equilibrium potential (calculated by the Nernst equation) for potassium>
The resting membrane potential is not exactly equal to the equilibrium potential for potassium because the membrane has some resting permeability to species other than potasium
A student new to neuroscience research is practicing recording resting membrane potentials from giant squid axons. During one of the trials, the resting membrane potential, which is normally around -60 mV, measured -15 mV. Which statement best describes what might have occurred during the experiment?
The student added too much potassium to the extracellular solution.
Is sodium concentration higher outside or inside of nerve cells?
Sodium is higher outside cells than inside cells
When current is injected into an axon…
The current will decay exponentially with increased distance from the injection sire (if no action potential is present)
what phenomenon explains the unidirectional propagation of action potentials
the presence of the refractory period at a location where an action potential has just passed
when does the refractory period end?
when the sodium channels are no longer inactivated
For which reason was the development of the voltage clamp critical to investigations of the ionic basis of the action potential?
Voltage clamping allows simultaneous control of membrane potential and measurement of permeability changes
