In the normal axon, reverse propagation of the action potential is not possible because the membrane is
A) Refractory because of sodium channel inactivation B) Refractory owing to potassium channel inactivation C) Refractory as a result of sodium ion influx D) Refractory because of potassium ion influx E) At its resting potential
A 31-year-old woman is diagnosed with depression and prescribed a selective serotonin reuptake inhibitor. Which of the following is a precursor of serotonin?
A) Lysine B) Glutamine C) Tryptophan D) Histidine E) Threonine