Important Concepts 2 Flashcards
What are receptors?
Chemical structures composed of proteins that receive and transduce signals for biological system.
What is the role of an agonist?
Bind to and activate their target receptors to produce a response
What is the role of an antagonist?
Bind to a receptor thereby preventing the usual ligand/substrate from binding. They reduce the activity of their target.
- no response
What is the key concept in toxicology?
Dose - the dose makes the poison
What is a dose-response relationship?
The correlation between the dose of a chemical
(drug or toxicant) and an organism’s response
What is a concentration-response relationship?
The correlation between the concentration of a chemical and a biological response in a site of action where the specific concentration can be determined.
What can dose-response relationships help define or compare?
Potency and efficacy
Define potency
the amount of drug required to produce an effect of given intensity.
How is differences in drug potency evaluated?
By comparing EC50 values
What is EC50 value?
median effective concentration
- 50% of the concentration that elicits a response
Define efficacy
The ability of a drug to produce a maximum response.
How are differences in drug efficacy evaluated?
By comparing differences in maximal response at high drug doses/concentrations
Define affinity
the tendency for a drug to bind to its receptor.
Once bound, the ability to switch to an active conformation is called efficacy.
LD50
median lethal dose
- quantity of a chemical estimated to be fatal to 50% of organisms
ID50/IC50
median inhibitory concentration
- Drug dose (concentration) that inhibits a biological process by 50%
