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FNA Module 1
Terms in this set (25)
Which cell type forms the myelin sheath?
Oligodendrocytes in the CNS
Ion channels that are involved in generation of action potentials open or close in response to
The resting membrane potential typically ranges from _____ to _____.
-40 mV; -90 mV
In a two-compartment model of a cell with K+-permeable membrane and a 10-fold excess of K+ in the inside compartment, how would K+ ions flow across the membrane?
They would flow from inside the compartment to outside the compartment.
The resting potential of a cell is negative because
at rest there is an excess of K+ inside the cell, and the membrane is chiefly permeable to K+.
What's the major deteminant of the permeability of a membrane to a specific ion?
Number of open ion channels specific for that ion.
Your friends has been told to calculate the equilibrium potential of K+. Which equation will he use, and what other info will he need?
Nernst equation; concentration of K+ inside and outside the cell
Squid axons - during one of the trials, the resting membrane potential is measured -15 mV instead of -60 mV. Which statement best describes what might have occurred during the experiment?
The student added too much K+ to the extracellular solution.
How does the resting membrane potential of a typical membrane compare to the equilibrium potential (Nernst equation) for K+?
The resting membrane potential is not exactly equal to the equilibrium potential for K+ because the membrane has some resting permeability to other ions than just K+.
Which statement about Na+ permeability during an action potential is most accurate?
It's responsible for the rising phase of the action potential.
An action potential only travels in one direction along the axon because of its _____ property.
A neuron has received enough stimulation to fire an action potential; it also has been treated with TEA, a K+ channel blocker. Which outcome is possible?
The cell will initially depolarize, but repolarization will take much longer because it relies only on ion pumps.
Where will voltage-gated Ca++ channels be most abundant?
Which property is characteristic of Na+ channels but not K+ channels?
ability to inactivate
The [not here] figure shows an electron micrograph of a chemical synapse in the cerebral cortex. Which statement about the synapse is correct?
Inside the presynaptic neuron are synaptic vesicles, which fuse with the membrane in the active zone.
Which treatment would prevent the release of NT from the presynaptic terminal?
A toxin that cleaves synaptobrevin
Minature End-Plate Potentials (MEPP) are produced
by spontaneous release of NT.
Which molecule binds NMDA receptors and prevents the flow of ions at resting and hyperpolarized membrane potentials?
In the falling phase of an action potential, _____ ions are moving _____ the cells.
potassium; out of
What would occur if the ATPase pumps in a neuron stopped functioning?
concentration gradients wouldn't be maintained across the membrane
The most important factor for determining whether a receptor-operated ion channel is inhibitory or excitatory is
whether the permeant ion's reversal potential is positive or negative to threshold.
What's the greatest advantage of the chemical signal transduction scheme?
Which second messenger originates from both extracellular and intracellular compartments?
Which of the following does not contribute to maintaining low levels of calcium in resting nerve cells?
voltage-gated ion calcium channels
Stimulation of metabotropic receptors cannot
open ion pores in the G-protein structure.
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