Twenty-year-old Kevin groaned and clutched his abdomen as he lay onthe emergency room gurney. He had just been diagnosed with acuteappendicitis and was waiting to be taken to the operating room(OR). Although he desperately wanted the pain to stop, Kevin wasterrified of having general anesthesia. He hoped his fear wasn’tobvious to his older brother Cole, who was finishing medical schooland thought he knew everything. "Hang in there," Cole said, for whatseemed like the eighteenth time. "I’m sure they’ll get you upstairsas soon as they can. They don’t want that thing to burst."Kevin grunted. "I know…but does that anesthesia stuff work all the time? How can I notwake up when someone’s slicing my gut open?" Cole assumed a professorial air, andKevin wished he’d kept his mouth shut. However, Cole didn’t get achance to say anything before an aide arrived to take Kevin to theOR. In the OR,someone placed a mask over Kevin’s face and when he blinked, hesuddenly found himself in a hospital room with Cole waiting in achair by the bed. "Welcome back to consciousness, little brother.How’s your abdomen feel?"
Kevinfrowned. "Not as bad as it did. So it’s over? How did I get herealready?". "You’ve been outfor a few hours," Cole chuckled, and then launched into the wondersof general anesthesia. "Certain neurons have to depolarize andcreate an action potential to maintain consciousness, but someanesthetics can hyperpolarize them and produce unconsciousness. Theanesthetic opens leaky potassium channels, which increases theleaky potassium current. However, it doesn’t affect voltage-gatedpotassium channels. This inhibits the neurons, and therefore youaren’t conscious of the surgeons performing the procedure. Amazingright?!". Kevingroaned again, but not from pain this time. Cole may be right buthe sounded like a textbook. "I’m just glad the stuff worked. Nowwhen can I go home?
Required:
a. How do depolarization and hyperpolarization relate tothreshold?
b. What does Cole mean when he says that anesthesia "inhibits theneurons?"
c. Is Cole correct that leaky potassium channels are differentfrom voltage-gated potassium channels? If they are differentexplain the differences.
d. Why are Kevin’s neurons less likely to produce actionpotentials when the anesthesia opens more potassium leakychannels?
