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Chapter 48. Neurons, Synapses, and Signaling. Questions prepared by Christopher Gregg Louisiana State University John Lepri University of North Carolina, Greensboro.
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Chapter 48 Neurons, Synapses, and Signaling Questions prepared by Christopher GreggLouisiana State University John LepriUniversity of North Carolina, Greensboro
Choose the correct pathway of information flow through neurons while taking a test, starting with reading a question and ending with marking an answer. • interneurons motor neurons sensory neurons effectors • effectors sensory neurons interneurons motor neurons • sensory neurons interneurons motor neurons effectors • interneurons sensory neurons motor neurons effectors
Adding a poison that specifically disables the Na+/K+ pumps to a culture of neurons will cause • the resting membrane potential to drop to 0 mV. • the inside of the neuron to become more negative relative to the outside. • the inside of the neuron to become positively charged relative to the outside. • sodium to diffuse out of the cell and potassium to diffuse into the cell.
For a nerve cell at its resting potential, the forces acting on potassium ions (K+) are a) none: K+ ions do not move at the resting potential. b) an electrical gradient, pulling K+ inward, and a chemical gradient, pushing K+ outward. c) an electrical gradient, pushing K+ outward, and a chemical gradient, pulling K+ inward. d) an electrical gradient, pulling K+ inward, and a chemical gradient, pushing K+ outward. e) an electrical gradient, pushing K+ outward, and a chemical gradient, pushing K+ outward.
A(n) ___ in Na+ permeability and/or a(n) ___ in K+ permeability across a neuron’s plasma membrane could shift membrane potential from −70 mV to −80 mV. • increase; increase • increase; decrease • decrease; increase • decrease; decrease
At time ZERO msec on the graph, it is likely that there was • a localized opening of K+ channels. • a localized opening of some Na+ channels. • a rapid opening of most K+ channels. • a rapid opening of most Na+ channels.
At step four in the graph, it is likely that • most Cl− channels closed. • most Na+ channels opened. • most K+ channels closed. • most K+ channels opened. • Na/K pumps were inactivated.
Of the following choices, the slowestconduction velocity for moving action potentials is likely seen in • a large-diameter, nonmyelinated axon. • a small-diameter, nonmyelinated axon. • A myelinated axon. • any of the above, as all neurons conduct action potentials at the same speed.
Injecting ethylene glycol tetraacetic acid (EGTA), a chelating agent that prevents calcium ions from moving across membranes, to a synaptic region would likely • increase the release of neurotransmitters by the presynaptic neuron. • decrease the release of neurotransmitters by the presynaptic neuron. • result in neurotransmitters being released, but could not bind to its receptors on the post synaptic neuron. • result in the lack of calcium ions keeping the ligand-gated ion channels open on the post synaptic neurons.
The use of organophosphate pesticides that inhibit acetylcholinesterase, an enzyme that breaks down acetylcholine, could cause skeletal muscle cells to • undergo more graded depolarizations, because acetylcholine would remain in the synaptic cleft longer. • undergo more graded hyperpolarizations, because acetylcholine would remain in the synaptic cleft longer. • undergo more graded depolarizations, because acetylcholine would prevent ligand-gated ion channels from opening. • undergo more graded hyperpolarizations, because excess acetylcholine opens Cl− channels.
Adderall, an amphetamine stimulant, works on the CNS by • increasing the release of GABA and decreasing its catabolism/reuptake. • increasing the release of serotonin and decreasing its catabolism/reuptake. • increasing the release of endorphins and decreasing their catabolism/reuptake. • increasing the release of dopamine and norepinephrine and decreasing their catabolism/reuptake.