Nerve MCQs Paper 1 2009 1. The resting potential of nerve cells is typically close to -70 mV. During an action potential this voltage can switch transiently to around +40 mV. Which of the following best describes the mechanism responsible for returning the potential back to -70 mV? A. The action of the Na+ / K+ pump in restoring the ionic gradients. B. The diffusion of Na+ down the nerve away from the active membrane. C. The efflux of K+ through channels. D. The degradation of acetylcholine. E. The development of a slow inward current. 2. Which of the following is released from the posterior pituitary? A. Antidiuretic hormone (ADH). B. Adrenocorticotrophic hormone (ACTH). C. Luteinizing hormone (LH). D. Thyroid stimulating hormone (TSH). E. Follicle stimulating hormone (FSH). 3. The equilibrium potential for calcium in a mammalian neurone is approximately +130 mV. For a typical nerve cell, if a monovalent cation had the same intracellular and extracellular concentrations as calcium, what would its equilibrium potential be? A. -6- mV. B. +66 mV. C. -130 mV. D. -260 mV E. +260 mV. 4. During a depolarising voltage clamp step an early inward current is followed by a late outward current. Which of the following accounts for the late outward current. A. Inward movement of Cl- ions. B. Outward movement of Na+ ions. C. Outward movement of K+ ions. D. Outward movement of calcium ions. E. Activity of the Na/K pump. Saltatory conduction gets its name from which of the following? A. Conduction of the potential through the ionic milieu of the axon. B. The description of the phenomenon by Johann Salta. C. The apparent jumping of the potential along the axon. D. The flow of Na+ and K+ between nodal regions. E. The high NaCl levels found between glial and nerve cells. 6. What is the typical conduction velocity of a mammalian motoneurone? A. 0.1 m s-1 B. 1 m s-1 C. - m s-1 D. -0 m s-1 E. -00 m s-1
7. The sodium pump maintains the normal low intracellular sodium ion concentration in animal cells. Which of the following descriptions of its properties is CORRECT? A. It pumps out 2 Na+ ions and pumps in 3 K+ ions for each ATP consumed. B. It is inhibited by curare. C. It generates a depolarizing current when hyperactive. D. Net Na+ extrusion is greatly reduced by the removal of extracellular K+. E. It pumps in 2 Cl- ions for every 3 Na+ ions pumped out. 8. Which of the following is a secondary active transporter? A. The sodium-potassium pump. B. The plasma membrane Ca2+ ATPase. C. The sodium-calcium exchanger . D. The sarcoplamic / endoplasmic reticulum calcium (SERCA) pump. E. Multidrug resistance transporters, or ABC transporters. 9. Which of the following processes causes the release of transmitter at a synapse? A. The increase in internal sodium concentration in the presynaptic terminal. B. The rapid repolarization of the presynaptic terminal. C. The post-synaptic release of potassium ions. D. Inhibition of the