A drug completely inhibits the sodium-potassium pumps in a neuron. The neuron may still generate action potentials briefly, but signaling eventually fails. Why is failure not necessarily immediate?

A patient takes a medication that mimics cortisol for several weeks. Assuming normal negative feedback, what should happen?

Match the drug to its drug class.

The same presynaptic neuron produces two identical excitatory postsynaptic potentials. When they occur far apart in time, the postsynaptic neuron does not reach threshold. When they occur in rapid succession, it does. Why?

Only a small number of hormone molecules bind to receptors on a target cell, yet the response inside the cell is large. How can a cAMP signaling pathway produce this amplification?

Short Answer Questions For the short-answer section, choose four of the five questions to answer. If you answer all five, I will grade the first four. Each response is worth 20 points. Answer all parts of each question you choose and show your reasoning clearly.   

Sympathetic postganglionic neurons normally release norepinephrine onto the heart, while parasympathetic postganglionic neurons release acetylcholine. A drug prevents norepinephrine from acting on cardiac cells but does not interfere with acetylcholine. What would you predict?

An enzyme removes most of the carbohydrate chains attached to proteins and lipids on the outside of a cell membrane, while leaving the phospholipid bilayer and transport proteins intact. Which function would be most directly disrupted?

After prolonged sweating, a person has lost a substantial amount of body water. The body responds by conserving water and increasing thirst. As fluid balance is restored, these responses decrease. What makes this an example of negative feedback?

The type of drug that would be most helpful for a patient with a productive cough is a/an: