Exam (elaborations) Neuroscience - Membrane Permiability

1. Which statement about Na+ permeability during an action potential is most accurate? a. It is long lasting. b. It is responsible for the rising phase of the action potential. c. It is responsible for the falling phase of the action potential. d. It restores the membrane potential to its usual level following the action potential. e. All of the above Answer: b Textbook Reference: Overview 2. Work done by _______ elucidated changes in membrane permeability that underlie an action potential. a. Alan Hodgkin and Bernard Katz b. Alan Hodgkin and Andrew Huxley c. Walther Nernst d. Kenneth Cole e. David Goldman Answer: b Textbook Reference: Ion Currents across Nerve Cell Membranes 3. The voltage clamp method controls the _______ at any desired level. a. amplitude of an action potential b. frequency of an action potential c. membrane potential d. K+ current e. Na+ current Answer: c Textbook Reference: Ion Currents across Nerve Cell Membranes 4. The classic voltage clamp technique would be suitable for which application? a. Indirect measurement of unidirectional current flowing through cell membrane b. Direct measurement of current flowing through the cell membrane c. Measurement of current flowing through a single ion channel d. Study of the ionic composition of the intracellular environment e. Evaluation of effects of large intracellular molecules on the function of ion channels Answer: b Textbook Reference: Ion Currents across Nerve Cell Membranes 5. Which current is produced in response to a hyperpolarizing stimulus in a giant axon of a squid? a. Inward capacitive current b. Outward capacitive current c. Transient inward current d. Delayed outward current e. Prolonged outward current Answer: a Textbook Reference: Ion Currents across Nerve Cell Membranes 6. Which current corresponds to a flow of Na+ in response to a depolarizing stimulus in a giant axon of a squid? a. Inward capacitive current b. Outward capacitive current c. Transient inward current d. Delayed outward current e. Prolonged outward current Answer: c Textbook Reference: Ion Currents across Nerve Cell Membranes 7. The voltage clamp apparatus has _______ electrodes, and the _______ compares the actual membrane potential with the command potential. a. two; amplifier b. two; reference electrode c. two; recording electrode d. three; amplifier e. three; reference electrode Answer: d Textbook Reference: Ion Currents across Nerve Cell Membranes 8. In voltage clamp experiments, the early current will disappear if the membrane is clamped at _______ mV. a. –26 b. 0 c. + 26 d. +52 e. +65 Answer: d Textbook Reference: Two Types of Voltage-Dependent Ion Currents 9. In the experiments conducted by Hodgkin and Huxley, the early current disappeared if the membrane was clamped at _______ mV. a. –26 b. 0 c. + 26 d. +52 e. +65 Answer: d Textbook Reference: Two Types of Voltage-Dependent Ion Currents