PRACTICE QUESTIONS DETAILED
SOLUTIONS
◉ What are the link between chemical actions and biological function?
Answer: Receptors
◉ Emax Answer: maximum effect of a drug
◉ What happens when Emax is reached? Answer: Emax occurs when all
receptors are bound
◉ What is in indication that spare receptors are present? Answer: When
Emax is reached before all receptors are bound
◉ Agonist Answer: has affinity for a receptor as well as intrinsic activity
at the receptor
◉ Antagonist Answer: has affinity for a receptor but no intrinsic activity
at the receptor
◉ partial agonist Answer: has affinity for a receptor but lacks the full
intrinsic activity of an agonist
◉ inverse agonist Answer: binds to a constitutively active receptor and
inactivates it
, ◉ affinity Answer: the propensity of a ligand to bind to a receptor
◉ high affinity = Answer: binds readily to a receptor
◉ low affinity = Answer: spends less time bound to a given receptor
◉ intrinsic activity Answer: the action carried out by the ligand while it
is bound to a receptor
◉ Kd Answer: dissociation constant (affinity of a drug for a receptor)
◉ What does the value of Kd signify? Answer: measures the propensity
of a drug to release (dissociate) from a receptor
◉ What does a high Kd mean? Answer: drug readily dissociates from its
receptor
◉ What does a low Kd mean? Answer: suggests high affinity for its
receptor
◉ If a patient were to overdose on a reversible antagonist, what could
you do? Answer: Add more agonist