Neurophysiology Practice 2

1. A second nerve impulse cannot be generated until ________. a. proteins have been resynthesized b. the Na ions have been pumped back into the cell c. the membrane potential has been reestablished d. all sodium gates are closed 2. The interior surface of a neuron's plasma membrane at resting membrane potential will have a ________. a. negative charge and contains less sodium than outside of the cell b. positive charge and contains more sodium than outside of the cell c. negative charge and contains more sodium than outside of the cell d. positive charge and contains less sodium than outside of the cell 3. Like all cells, the neurons' internal organization dictates its function. Neurons have relatively many mitochondria, an extensive network of rough endoplasmic reticulum and many clusters of ribosomes. These cellular features indicate all of the following EXCEPT ________. a. neurons have a relatively high consumption of oxygen b. neurons produce many proteins c. neurons must meet a high demand for ATP d. neurons have stable, relatively unchanging internal environments 4. The resting membrane potential results from a. activity of the sodium/potassium pump only. b. uneven distribution of ions across the cell membrane and differences in + + membrane permeability to Na and K . c. + + differences in membrane permeability to Na and K only. d. uneven distribution of ions across the cell membrane only. e. None of the answers are correct. 5. Which ion(s) is/are higher in concentration inside the cell compared to outside? a. sodium b. potassium c. calcium d. chloride e. More than one of the answers is correct. 6. The rising phase of the action potential is due to + a. Na flow out of the cell only. b. + K flow out of the cell only. c. + K flow into the cell only. d. + Na flow into the cell only. e. + + Na flow out of the cell and K flow into the cell. 7. The falling phase of the action potential is due primarily to + a. K flow out of the cell only. b. + K flow into the cell only. c. + Na flow in the cell only. d. + Na flow out of the cell only. e. + + Na flow out of the cell and K flow into the cell. 8. Choose all of the items that are incorrectly matched. a. activation gate — open at rest b. inactivation gate — closed at rest c. inactivation gate — closed during repolarization d. activation gate — opens during depolarization e. All of the answers are incorrectly matched. 9. The absolute refractory period of an action potential a. only prevents summation of action potentials. b. only ensures one-way travel down an axon. c. only allows a neuron to ignore a second signal sent that closely follows the first. d. ensures one-way travel down an axon, allows a neuron to ignore a second signal sent that closely follows the first, and prevents summation of action potentials. e. ensures one-way travel down an axon and allows a neuron to ignore a second signal sent that closely follows the first. 10. In order to signal a stronger stimulus, action potentials become a. longer-lasting only. b. higher in amplitude and longer-lasting. c. higher in amplitude only. d. higher in amplitude and more frequent. e. more frequent only. 11. All of the following must occur before a second action potential can begin, EXCEPT a. the absolute refractory period must occur. b. + + the Na and K ions that moved in/out of the cell must move back to + their original compartments; the Na inactivation gate must open; and the + Na activation gate must close. c. + + the Na and K ions that moved in/out of the cell must move back to their original compartments. + + d. the Na inactivation gate must open and the Na activation gate must close. e. None of the answers are correct. 12. Voltage-regulated channels are located a. within the cytosol only. b. in the membranes of axons only. c. on the neuron cell body only. d. in the membranes of dendrites only. e. in the membranes of dendrites, in the membranes of axons, and on the neuron cell body.