pharmacodynamics

any substance that causes a response by the body 

Drug

scientific study of the effects of drugs on living organism  

Pharmacology

• means from inside of body 

Endogenous

• means from outside of body

Exogenous

• molecules that bind to receptors

Ligand

• drug that activates the receptor

Agonist

drug that inhibits or prevents receptor activation

Antagonist

• receptors exist in a reversible equilibrium between inactive and active states

Active/inactive Receptor

• concentration dependent toxic effects of drugs 

Averse Effect

use of drugs in medicine

Pharmacotherapy

• refers to drug receptor’s ability to bind to one target or molecule with greater affinity over another 

Drug selectivity

• way drug works on our bodies and tells us how a drug influences its target to elicit a biological response 

mechanism of action 

the magnitude of response is proportional to the number of drug-receptor complexes formed

Drug receptor complex and response

• biochemical change in a cell produced when a drug interacts with a receptor; described as the receptor handling the signal to downstream parts of a cascade that produce the biological response  

Signal transduction

• where the alphas subunits bind GTP subunits dissociate and signal downstream effectors 

G-protein coupled receptor

•  channels normally closes; ligand binding causes a conformational change that opens the channel and allows ions to flow, mediating rapid signaling 

Ligand Gated Ion Channels

channels regulated by membrane potential; they permit ion flow in response to voltage changes

Voltage Gated Ion Channels

 receptors located inside the cell; ligand must be membrane-permeable. Once activated they act on DNA to alter gene/protein expression’ effects are typically slow

Intracellular Receptor

receptor that when activated increase intracellular enzyme activity 

Enzyme Linked Receptors

repeated or continuous agonist exposure leads to receptor modification

Desensitization

this exact term is not explicitly defined, refers to functional loss of receptor/channel activity

Inactivation

 repeated agonist exposure leads to internalization or destruction of receptors, reducing receptor number on surface

Down regulation

• repeated exposure to antagonist increases receptor number making cells more sensitive to agonist 

Upregulation

• one ligand-receptor interaction leads to multiple downstream signals 

Signal amplification

• systems where maximal response can be achieved without occupying all receptors (consequence of signal amplification)

spare receptors