Receptors Flashcards
(25 cards)
_________ drugs facilitate receptor functions, while __________ drugs block receptor functions.
Agonist; antagonist
T/F: An antagonist will block the agonist from causing a physiological effect.
True
Pilocarpine and atropine produce their effects by acting on _________________ of salivary glands.
Muscarinic acetylcholine receptor proteins
Muscarinic antagonists can produce __________.
Xerostomia
Who came up with the receptor theory?
Langley studied curares antagonist activity on nicotine to muscle cells
What is described by the equilibrium or dissociation constant ?
Drug concentration required for 1/2 maximal binding to the receptor (Kd)
What is the general idea of uptake kinetics by a receptor?
Receptors will quickly become saturated to a point and will then slowly take up substrate (rectangular hyperbola)
How would drugs with different Kd act differently in how they are bound by receptors?
A drug with a higher Kd would require higher concentrations to create the same effect as one with a lower Kd
Higher Kd = drug will come off of receptor more easily
T/F: If X amount of drug produces a certain effect, 2X amount of drug will produce roughly twice as much of an effect.
FALSE
Depends on where you are on binding curve
If original amount is low - doubling may induce double the effect
If original amount is high - doubling may have very little additional effect
Drugs exert their effects by __________.
Binding to a receptor
The _________________ describing drug binding to its receptor is defined as the concentration of drug providing 1/2 maximal binding.
Dissociation constant
Which type of curve allows for a more complete range of data to be shown?
Sigmoidal curve
The law of mass action is a fine way to describe drug ___________, but does not accurately describe quantitiative aspects of drug _________.
Binding; action
What is EC50?
This is the dose of drug that produces 1/2 the maximal effect
Maximum drug effect is seen when drug concentrations greatly exceed the ________.
EC50
T/F: There is a maximal pharmacological effect where once a drug reaches a certain level, more drug will not produce an additional effect.
True
Is EC50 (1/2 maximal effect) the same as Keq (1/2 maximal binding)?
No because often EC50 is less than Keq (1/2 maximal effect is seen at less than 1/2 maximal binding)
Why are partial agonists not as effective as full agonists?
Partial agonists activate a lower fraction of receptors, independent of their relative binding affinities
What is the difference between binding affinity and efficacy?
Binding affinity: determines concentration dependence of drug action
Efficacy: the ability to confer the physiologic response
Together, efficacy and binding affinity determine a drugs __________.
Potency
Drugs with insufficient efficacy will be _____________ regardless of how well they bind to their receptor.
Partial agonists
Drugs with no efficacy that bind to the receptor will be ____________.
Antagonists
T/F: Receptors are characterized by their physiologic response, not their pharmacology.
False
Receptors are characterized by their pharmacology
T/F: There are typically inhibitory receptors and excitatory receptors.
False
Receptors often have several functions
