pharmacodynamics: target tissue receptors Flashcards
what is a receptor
component on or within a cell that a substance can bind to
when a drug binds to the receptor
it initiates a biochemical chain of events
receptor that recognize as endogenous and exogenous compounds often have a ..
binding site on the outer surface of the cell membrane
what are many surface receptors ?
transmembrane proteins
surface receptors act as an
ion channel and directly altering membrane permeability
receptors become an
ion pore and change the membrane permeability
ex: acetylcholine receptor
what is found on neuronal membranes in the CNS
GABA
drugs and endogenous chemicals that bind to the receptor side can..
change the enemy me activity of the intracellular catalytic compound ; thus changing the biochemical function within the cell
common example of a receptor enzyme system
receptor tyrosine kinase protein
surface receptors linked to regulatory (G) proteins
affect the cell function by linking to an intracellular intermediate regulatory protein (g protein), activated by binding guanine nucleotides
when a druge attaches to a G protein what happens
alters the activity of an intracellular effector ; leading to change in cell function
how does the drug act as a first messenger when linked to a G protein
it triggers a biochemical change in the cell but the drug itself does not enter
what does the secondary messenger do when a surface receptor is linked to a G protein?
it is the substance produced inside the cell, actually mediated the change in function
what is the primary example of secondary messenger
adenylate cyclase cyclic adenosine monophosphate (cAMP)
adenylate cyclase is responsible for hyrolyzing adenosine triphosphate into
cAMP
where are intracellular receptors located
within the cytoplasm and/or nucleus
what are intracellular receptors specific for ?
certain endogenous hormones and hormone like drugs
ex: steroids
the drugs ability to bind to any receptors depends on
the drugs size and shape relative to the confirguation of the receptors binding site
define affinity
the amount of attraction between a druge and a. receptor
what is affinity related to ?
the drug amount that is required to bind to the unoccupied receptors
a drug with high affinity ..
binds readily to the open receptors , even if the concentration of the drug is low
drugs with moderate or low affinity require a
higher concentration in the body before the receptors become occupied
what are allosteric modulators
local receptors that are distinct from the primary binding site and there by increase or decrease the affinity for the drug
what is affinity influenced by ?
local regulators (allosteric modulators) and environments (membrane fluidity and organization)
a drug is sadi to be selective if
it affects only one type of cell or tissue and produces a specific physiological response
the fact that we can classify many receptors into subtypes means we can develop
drugs that will affect only one receptors subtype and therefore produce fairly selective effected with few side effects
the dose response is
related to the number of receptors that are bound by the drug
the dose response is typically
proportional to the number of receptors occupied by the drug
not linear
agonist drugs
has both affinity and efficacy
antagonist drugs
has only affinity and it occupies the celeste to block the effect of another chemical (bad guy)
define drug efficacy
indicated that the drug will activate the receptor and change the function of the cell
competence antagonists
vie for the same receptor as agonist
equal opportunity
whichever drug concentration is higher
agonist can overcome the antagonist
no competitive antagonist
irreversible bonds
inability of agonist to compete with anatagonist
terminated only with normal protein turnover
drugs that do not evoke a maximal response compared to a strong agonist is called
partial agonist , they occupied all availed receptors
what is it called when some agents will similar certai receptors subtypes while simultaneously black the effects of endogenous suzanne’s on other receptor subtypes
mixed agonist antagonist
Overstimulation of postsynaptic receptors may lead to a decrease in responsiveness of the receptors. A fairly brief and transient decrease in receptor responsiveness is known as _____, whereas a more prolonged process in which the actual number of available receptors is diminished is known as _________.
desensitization: down regualtions
define receptor internalization
receptors are withdrawn from the cell membrane by endocytosis
define down regulation
describes a slower, more prolonged process in which the number of availed receptors is diminished
