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Pharmacodynamics
receptors, agonists vs antagonists, dose response curves
91
Nursing
Graduate
09/04/2014

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Term
WHAT IS PHARMACODYNAMICS?
Definition
WHAT THE DRUG DOES TO THE BODY.
Term
WHAT DOES PHARMACODYNAMICS ADDRESS? 3 ANSWERS
Definition
THE MECHANISM OF ACTION (MOA), RECEPTOR INTERACTIONS, AND DRUG EFFECTS
Term
FOR A PHYSIOLOGIC RESPONSE TO OCCUR, DRUGS MUST HAVE INTERACTION WITH WHAT?
Definition
A RECEPTOR
Term
WHAT FORMS CAN THE DRUGS BE? 5 ANSWERS
Definition
EXOGENOUS SUBSTANCE THAT WE ADMINISTER, HORMONE, ENZYME, NEUROTRANSMITTER, OR OTHER ENDOGENOUS COMPOUND...THESE ARE CALLED LIGANDS
Term
WHAT ARE THE 2 VARIABLES RELATED TO ED50? WHAT DO THEY MEAN?
Definition
DEPENDS ON WHETHER THE MEASUREMENT IS GRADED OR QUANTAL. GRADED RELATIONSHIPS ARE CONTINUOUS (PAIN SCALE 0-10). QUANTAL RELATIONSHIPS ARE ALL-OR-NONE (DID IT WORK OR NOT?)
Term
WHAT IS THE DEFINITION FOR GRADED ED50?
Definition
DOSE REQUIRED TO PRODUCE 50% OF THE MAXIMAL EFFECT.
Term
WHAT IS THE DEFINITION FOR QUANTAL ED50?
Definition
DOSE THAT PRODUCED THE DESIRED OUTCOME IN 50% OF THE PATIENTS.
Term
WHAT IS TD50?
Definition
THE DOSE REQUIRED TO PRODUCE A TOXIC EFFECT FOR 50% OF THE POPULATION. MAY HAVE A DIFFERENT NUMBER ATTACHED LIKE ED50, ED95
Term
WHAT IS LD50?
Definition
THE LETHAL DOSE FOR 50% OF THE POPULATION (MAY BE THE SAME AS THE TOXIC DOSE). MAY HAVE A DIFFERENT NUMBER ATTACHED LIKE ED90, ED95
Term
WHAT IS A THERAPEUTIC INDEX? WHAT IS THE EQUATION?
Definition
THE RATIO OF THERAPEUTIC (EFFECTIVE) TO TOXIC DOSE. TI=TD50/ED50
Term
WHAT DOES IT MEAN IF YOU HAVE A WIDE THERAPEUTIC INDEX?
Definition
YOU HAVE A WIDE MARGIN OF SAFETY
Term
WHAT DOES IT MEAN IF YOU HAVE A NARROW THERAPEUTIC INDEX?
Definition
YOU HAVE A NARROW MARGIN OF SAFETY.
Term
WHAT IS POTENCY?
Definition
HOW MUCH DRUG DOES IT TAKE TO ELICIT A RESPONSE.
Term
WHAT DOES POTENCY BETWEEN DRUGS MEAN?
Definition
IT IS MEASURED BY THE DOSE IT TAKES TO ELICIT THE SAME RESPONSE. EX DILAUDID IS MORE POTENT THAN MORPHONE BECAUSE IT TAKES 1MG OF DILAUDID TO ELICIT THE SAME RESPONSE AS 10MG OF MORPHONE.
Term
IF YOU HAVE 2 DRUGS WITH CERTAIN ED50, WHICH ONE WHOULD BE MORE POTENT?
Definition
THE DRUG WITH THE LOWER ED50.
Term
WHAT IS AFFINITY? GIVE SOME EXAMPLES.
Definition
HOW MUCH A DRUG/CHEMICAL "LIKES" ITS RECEPTOR. A DRUG WITH A HIGH AFFINITY FOR IT'S RECEPTOR BINDS EASILY, AND A LOWER CONCENTRATION OF A DRUG MAY BIND ENOUGH RECEPTORS TO ELICIT A RESPONSE.
Term
IN REPONSE TO AFFINITY, TYPICALLY WHAT IS THE PHYSIOLOGIC RESPONSE FROM?
Definition
DRUG CONCENTRATION
Term
WHAT DOES EFICACY MEAN?
Definition
IT IS THE EFFECTIVENESS. IS IT THE MAXIMAL RESPONSE PRODUCED BY A DRUG.
Term
WHAT ARE QUESTIONS TO ASK ABOUT EFFICACY?
Definition
CAN THE DRUG PRODUCE AN EFFECT? MORE SPECIFICALLY, IS THE DRUG CAPABLE OF PRODUCING THE MAXIMAL EFFECT?
Term
HOW DOES AGONISTS, PARTIAL AGONISTS, AND ANTAGONISTS DISPLAY EFICACY?
Definition
AGONISTS DISPLAY MAXIMAL EFFICACY, PARTIAL AGONISTS HAVE LESS THAN MAXIMAL EFFICACY, AND ANTAGONISTS HAVE NO EFFICACY.
Term
WHAT IS EFFICACY ALSO KNOWN AS?
Definition
INTRINSIC ACTIVITY.
Term
WHAT IS A RECEPTOR?
Definition
IT IS THE SITE OF ACTION OF A DRUG
Term
WHAT CAN RECEPTORS BE? 4 ANSWERS
Definition
RECEPTORS CAN BE A PROTEIN, CYTOPLASMIC OR EXTRACELLULAR ENZYME, OR A NUCLEIC ACID
Term
WHAT IS A DEFINITION AND EXAMPLE OF A GENERALIZED RECEPTOR?
Definition
GENERALIZED RECEPTORS ARE THOSE THAT HAVE FUNCTIONS ESSENTIAL TO A CELL'S NORMAL PHYSIOLOGIC FUNCTION. EX. DNA, PROTON PUMPS OF THE STOMACH, ETC..
Term
WHAT IS A SPECIALIZED RECEPTOR AND GIVE AN EXAMPLE?
Definition
SPECIALIZED RECEPTORS ARE MOLECULES THAT HAVE EVOLVED SPECIFICALLY TO REACT TO ENDOGENOUS OR EXOGENOUS CHEMICAL COMPOUNDS. EX. ALPHA AND BETA ADRENERGIC RECEPTORS, CHLORIDE ION CHANNELS, ETC..
Term
WHAT MODEL DEPICTS HOW DRUGS BIND TO THE RECEPTOR?
Definition
THE LOCK AND KEY THEORY. THE DRUG MUST FIT THE RECEPTOR AND BE ABLE TO ACTIVATE IT.
Term
WHAT DETERMINES HOW LONG THE DRUG'S EFFECT WILL LAST, AND WHEATHER OR NOT THE BOND IS REVERSIBLE?
Definition
CHEMICAL BONDS
Term
WHAT ARE THE DIFFERENT TYPES OF CHEMICAL BONDS? 5 ANSWERS
Definition
COVALENT BONDS, IONIC BONDS, HYDROGEN BONDS, HYDROPHOBIC BONDS, AND VAN DER WAALS BONDS
Term
WHAT IS A COVALENT BOND?
Definition
STRONG BONDS WHICH NEED ENERGY TO BREAK (ERREVERSIBLE DRUG-RECEPTOR BINDING)
Term
WHAT IS AN IONIC BOND?
Definition
STRONG BONDS THAT MAY BE REVERSED OR BROKEN BY A CHANGE IN pH.
Term
WHAT IS A HYDROGEN BOND?
Definition
MODERATELY STRONG BONDS AMONG H,N,F, AND O.
Term
WHAT IS A HYDROPHOBIC BOND?
Definition
IT IS MORE OF A WEAK FORCE. WHEN A PROTEIN STRUCTURE WHICH ARE REPELLED BY AQUEOUS SOLUTIONS TOWARD EACH OTHER.
Term
WHAT IS A VAN DER WAALS BOND?
Definition
VERY WEAK BONDS THAT ARE EASILY BROKEN
Term
WHAT DOES MOST DRUG - RECEPTOR BONDS CONSIST OF?
Definition
SEVERAL WEAK BONDS.
Term
WHAT IS A SIGNAL TRANSDUCTION?
Definition
ONCE THE DRUG AND RECEPTOR BIND, A CONFORMATIONAL CHAGNE OCCURS IN THE RECEPTOR AND A SIGNALING PATHWAY IS ACTIVATED WHICH IS CALLED A SIGNAL TRANSDUCTION.
Term
THE TYPE OF ______ DETERMINES WHAT "SIGNAL" IS SENT, AND THE PHYSIOLOGIC EFFECT.
Definition
RECEPTOR
Term
WHAT ARE THE TYPES OF RECEPTORS? 4 ANSWERS
Definition
G-PROTEIN COUPLED RECEPTORS, LIGAND-GATED ION CHANNELS, TYROSINE KINASE RECEPTORS, AND NUCLEAR HORMONE RECEPTORS.
Term
DESCRIBE GPCR.
Definition
A HUGE FAMILY OF RECEPTORS THAT IS RESPONSIBLE FOR A LARGE RANGE OF FUNCTIONS INCLUDING SMELL AND SIGHT, IMMUNE FUNCTIONS, BEHAVIOR AND MOOD, AND ANS FUNCTIONS.
Term
WHAT DOES GPCR INCLUDE?
Definition
OPIOID, ADRENERGIC, HISTAMINE, ETC.. MOST OF OUR DRUGS ACT ON GPCRs.
Term
HOW MANY TIMES DOES GPCR SPAN THE CELL MEMBRANE?
Definition
7 TIMES
Term
INTRACELLULAR HOW MANY SUBUNITS ARE THERE?
Definition
3 WHICH ARE A,B,Y
Term
DESCRIBE THE SUBUNITS A,B,Y.
Definition
THE B AND Y SUBUNITS ARE SO TIGHTLY BOUND THAT THEY DO NOT SEPARATE. THE A SUBUNIT IS THE MORE ACTIVE UNIT.
Term
WHAT IS BOUND TO THE A SUBUNIT IN THE INACTIVATED STATE OF THE RECEPTOR?
Definition
GDP (GUANASINE DIPHOSPHATE)
Term
WHAT HAPPENS WHEN A LIGAND BINDS TO THE EXTRACELLULAR PORTION OF THE RECEPTOR?
Definition
1) A CONFOMATIONAL CHANGE OCCURS IN THE RECEPTOR. 2) THE GDP ON THE A SUBUNIT IS REPLACED WITH GTP. 3) THIS CAUSES THE B/Y SUBUNITS TO DISSOCIATE FROM THE A SUBUNIT. 4) THE (NOW ACTIVATED) A SUBUNIT IS AVAILABLE TO ACTIVATE THE ADENYLY CYCLASE IN THE CELL. 5) THE ADENYLY CYCLASE STIMULATES THE CONVERSION OF ATP TO cAMP. 6) cAMP ACTIVATES PROTEINS (PROTEIN KINASE A), WHICH HAVE VERY TISSUE SPECIFIC EFFECTS
Term
THE A SUBUNIT CAN BE ONE OF SEVERAL TYPES. WHAT ARE THEY?
Definition
s (STIMULATING)- INCREASES ADENYLY CYCLASE AND THEREFORE INCREASES THE PRODUCTION OF cAMP. I (INHIBITORY)- DECREASES ADENYLYL CYCLASE ACTIVITY AND THEREFORE REDUCES THE PRODUCTION OF cAMP. q ACTIVATES PHOSPHOLIPASE C WHICH FORM INOSITOL TRIPHOSPHATE (IP3) AND DIACYLGLYCEROL (DAG) FROM THE MEMBRANE PHOSPHOLIPIDS
Term
WHAT DOES IP3 AND DAG DO WHICH IS FORMED BY PHOSPHOLIPASE C THAT IS ACTIVATED BY q?
Definition
IP3 AND DAG CAUSE AN INCREASE IN INTRACELLULAR CALCIUM WHICH IS IMPORTANT IN MUSCLE CONTRACTION AND NEUROTRANSMITTER RELEASE, AMONG OTHER THINGS.
Term
WHAT ARE THE 4 SECOND MESSENGERS AND WHAT DO THEY DO?
Definition
cAMP, IP3, DAG, AND CALCIUM ARE CALLED SECOND MESSENGERS BECAUSE THEY CAUSE CERTAIN ENZYMATIC REACTIONS IN TARGET CELLS THAT EVENTUALLY LEAD TO A PHYSIOLOGIC EFFECT.
Term
WHAT IS cAMP DEGRADED TO by what?
Definition
5'-AMP by phosphodiesterase
Term
DESCRIBE A LIGAND-GATED ION CHANNEL.
Definition
LIGAND GATED= A LIGAND HAS TO OPEN THE GATE (ION CHANNEL)
Term
A LIGAND IS A PROTEIN WITH HOW MANY SUBUNITS ATTACHED?
Definition
4-5 (TETRAMETRIC OR PENTAMETRIC)
Term
WHAT IS UNIQUE ABOUT THE SUBUNITS?
Definition
THE SUBUNITS ARE SPECIFIC TO DIFFERENT TISSUES. EX. THE NICOTINIC RECEPTOR IN THE AND IS DIFFERENT THEN THE NICOTONIC RECEPTOR IN THE NEUROMUSCULAR JUNCTION...SO EVEN THOUGH IT IS THE SAME RECEPTOR AND BOTH REPOND TO ACH, THEY HAVE DIFFERENT EFFECTS AND DIFFERENT DRUGS THAT BIND
Term
WHAT HAPPENS HAVE THE RECEPTOR IS ACTIVATED BY A LIGAND?
Definition
ONCE ACTIVATED BY A LIGAND, THE ION CHANNEL IS OPENED AND THE RECEPTOR SPECIFIC ION (NA, CL, ETCC.) ((ELECTROSPECIFIC ION)) RUSHES IN AND CAUSES A CHANGE IN THE MEMBRANE POTENTIAL, WHICH *ACTIVATED* OR *INHIBITS* SOME CELLULAR FUNCTION.
Term
ARE THERE ANY SECOND MESSENGERS IN ION CHANNEL (LIGAND CHANNEL) RECEPTOR ACTIVATION?
Definition
NO
Term
WHAT IS TYROSINE KINASE RECEPTORS ALSO KNOWN AS?
Definition
TRANSMEMBRANE ENZYME LINKED RECEPTORS
Term
TYROSINE KINASE RECEPTORS ARE BEING RECOGNIZED WITH GROWING IMPORTANCE WHERE/HOW? 3 ANSWERS
Definition
HUMAN GENOMIC MAKEUP AND ARE RESPONSIBLE FOR COUNTLESS CELLULAR PROCESSES, INCLUDING PROLIFERATION OF CANCER CELLS.
Term
HOW DOES TYROSINE KINASE RECEPTORS FUNCTION AS?
Definition
AND ON/OFF SWITCH
Term
WHAT HAPPENS TO A TYROSINE KINASE RECEPTOR IF A MUTATION RENDERS THE RECEPTOR IN THE STUCK POSITION?
Definition
THE MUTATED CELL PROLIFERATES UNCONTROLLED (CANCER CELLS, SO THESE RECEPTORS ARE A LARGE TARGET FOR MANY ANTI-NEOPLASTIC DRUGS
Term
THE TYROSINE KINASE RECEPTORS, ALTHOUGH DOESN'T INTERACT WITH ANESTHETIC DRUGS OFTEN, INTERACT WITH WHAT?
Definition
RECEPTORS OF INSULIN, HUMAN GROWTH FACTOR, VASCULAR ENDOTHELIAL GROWTH FACTOR, AND MANY OTHER IMMUNOLOGICAL AND HORMONAL RECEPTORS.
Term
ON A TYROSINE KINASE RECEPTOR WHERE DOES THE LIGAND BIND AND WHERE DOES THE TYROSINE KINASE POSITIONED AT?
Definition
THE LIGANDS BIND AT THE CELL SURFACE AND THERE IS AN INTRACELLULAR COMPONENT WHICH CONTAINS THE TYROSINE KINASE
Term
WHAT IS A KINASE?
Definition
A KINASE IS AN ENZYME THAT TRANSFERS PHOSPHOROUS FROM ATP TO SPECIFIC TARGETS...THIS IS CALLED PHOSPHORYLATION.
Term
TYROSINE KINASES SPECIFICALLY PHOSPHORYLATE WHAT?
Definition
TYROSINE AMINO ACIDS
Term
WHAT HAPPENS TO A TYROSINE KINASE RECEPTOR ONCE THE LIGAND BINDS TO THE RECEPTOR?
Definition
THE RECEPTOR DIMERIZES (2 STRUCTURES JOIN TOGETHER)
Term
WHAT HAPPENS AFTER A TYROSINE KINASE RECEPTOR DIMERIZES?
Definition
PHOSPHORYLATION OCCURS WHICH ACTIVATED A NUMBER OF SECOND MESSENGER SIGNAL TRANSDUCION MECHANISMS. THESE IN TURN CAUSE A PHYSIOLOGIC EFFECT SPECEFIC TO THE LIGAND AND SECOND MESSENGER SYSTEM.
Term
WHERE ARE NUCLEAR HORMONE RECEPTORS LOCATED?
Definition
IN THE CYTOPLASM OF THE CELL
Term
LIGANDS TYPICALLY EXIST IN WHAT FORM? HYDROPHOBIC, HYDROPHILIC, ETC..
Definition
HYDROPHOBIC (LIPOPHILIC) BECAUSE THEY HAVE TO CROSS THE MEMBRANE
Term
NAME 4 EXAMPLES OF HYDROPHOBIC LIGANDS.
Definition
SEX HORMONES, GLUCOCORTICOIDS, MINERALCORTICOIDS, AND THYROID HORMONES
Term
ONCE THE HYDROPHOBIC LIGANDS ATTACHE TO THE NUCLEAR HORMONE RECEPTORS IN THE CYTOPLASM OF THE CELL WHAT HAPPENS?
Definition
THE HORMONE BINDS TO A RECEPTOR IN THE CYTOPLASM WHICH TRAVELS TO THE NUCLEUS IN THE CELL. IN THE NUCLEUS THE RECEPTOR COMPLEX BINDS TO SPECIFIC DNA SEQUENCES AND ALTERS GENE TRANSCRIPTION.
Term
WHAT ARE AGONISTS?
Definition
LIGANDS THAT ACTIVATE A RECEPTOR AND PRODUCE A PHYSIOLOGIC RESPONSE (THE KEY FITS, AND IT TURNS THE LOCK)
Term
WHAT ARE ANTAGONISTS?
Definition
ARE LIGANDS THAT BIND TO A RECEPTOR, BUT DO NOT ACTIVATE IT (THE KET FITS, BUT IT WON'T TURN THE LOCK...BUT NOW YOU CAN'T PUT ANOTHER KEY IN)
Term
WHAT DO ANTAGONISTS PREVENT FROM BINDING TO THE RECEPTOR?
Definition
AGONISTS
Term
WHERE CAN AN ANTAGONIST BIND TO?
Definition
ANTAGONISTS MAY BIND TO THE ACTIVE BINDING SITE ON THE RECEPTOR OR TO AN ALLOSTERIC SITE. AN ALLOSTERIC AGONISTS MAY ALSO ALTER THE EFFECT OF AN ACTIVE AGONIST.
Term
WHAT HAPPENS IF AN ANTAGONISTS BINDS TO A ALLOSTERIC SITE?
Definition
BINDING AT AN ALLOSTERIC SITE DOES NOT PREVENT AN AGONIST FROM BINDING, BUT IT PREVENTS RECEPTOR ACTIVATION.
Term
WHAT IS COMPETITIVE ANTAGONISTS?
Definition
COMPETITIVE ANTAGONISTS COMPETE FOR THE SAME ACTIVE SITE ON A RECEPTOR AS THE AGONIST.
Term
ARE COMPETITIVE ANTAGONISTS REVERSIBLE?
Definition
YES
Term
COMPETITIVE ANTAGONISTS CAN BE OVERCOME BY WHAT?
Definition
ANTAGONISTS CAN BE OVERCOME BY AN AGONIST IF THE CONCENTRATION OF THE AGONIST AND ITS AFFINITY FOR THE RECEPTOR IS ADEQUATE.
Term
WHAT DOES THE COMPETITIVE ANTAGONISTS DO TO THE AGONISTS?
Definition
THE POTENCY OF THE AGONISTS IS REDUCED (YOU'LL NEED MORE IN ORDER TO ACHIEVE THE SAME RESPONSE).
Term
WHAT DOES COMPETITIVE ANTAGONISTS DO TO THE LIGANDS?
Definition
THEY DIFFUSE OFF OF THE RECEPTOR AND ARE ELIMINATED
Term
WHAT IS A NONCOMPETITIVE ANTAGONISTS?
Definition
A NONCOMPETITIVE ANTAGONISTS BIND TO THE RECEPTOR WITHA COVALENT BOND, LEAVING THE RECEPTOR UNAVAILABLE FOR AGONIST BINDING OR BIND (REVERSIBLY OR IRREVERSIBLY) TO AN ALLOSTERIC SITE. ONCE ENOUGH OF THE RECEPTORS ARE BOUND BY NONCOMPETITIVE ANTAGONISTS, IT MAY BE IMPOSSIBLE FOR AN AGONIST TO ILLICT A MAXIMAL RESPONSE. THEREFORE THE EFFICACY OF THE AGONIST IS DIMINISHED.
Term
WHAT MUST BE FORMED IF BOND IS IRREVERSIBLE RELATED TO NONCOMPETITIVE ANTAGONISTS?
Definition
NEW RECEPTORS. EX. ASA BIND IRREVERSIBLY TO INACTIVATE PLT AGGREGATION..THE EFFECT LASTS APROX. 7-10 DAYS UNTIL NEW PLTS ARE FORMED.
Term
WHAT IS ANOTHER NAME FOR PARTIAL AGONISTS?
Definition
AKA AGONIST/ANTAGONIST
Term
WHAT IS A PARTIAL AGONISTS?
Definition
DRUGS THAT ARE UNABLE TO CAUSE A FULL CONFORMATIONAL CHANGE TO A RECEPTOR.
Term
WHAT HAPPENS IF A PARTIAL AGONIST IS BOUND AND A FULL AGONISTS BINDS AS WELL?
Definition
THE RESPONSE TO A FULL AGONIST WILL BE PARTIALLY INHIBITED. SAID TO HAVE SOME AGONIST AND SOME ANTAGONIST EFFECTS
Term
WHAT DOES A CHEMICAL ANTAGONIST DO?
Definition
SOME MEDICATIONS DO NOT BIND TO A RECEPTOR TO CAUSE THEIR EFFECT, BUT RATHER INTERCEPT ANOTHER CHEMICAL OR DRUG BEFORE IT HAS THE OPPORTUNITY TO ACT. EX. PROTAMINE IS GIVEN TO COUNTERACT THE EFFECTS OF HEPARIN. IT WORKS BY FORMING AN IONIC BOND WITH HEPARIN (HEPARIN IN NEGATIVELY CHARGED COMPOUND WHEREAS PROTAMINE IS A POSITVELY CHARGED)
Term
IN RELATION TO DOSE RESPONSE CURVES WHAT IS THE X AND Y AXIS?
Definition
THE X AXIS IS THE DOSE OR CONCENTRATION OF DRUG (TYPICALLY IN LOGARITHMIC FORM). THE Y AXIS IS THE EFFECT OR RESPONSE.
Term
HOW DOES THE SHAPE OF THE CURVE EFFECT MARGIN OF SAFETY.
Definition
STEEP CURVES REPRESENT DRUGS WITH A NARROW MARGIN OF SAFETY (SMALL CHANGES IN THE DOSE CAUSE LARGE CHANGES IN THE RESPONSE). WIDE CURVES REPRESENT DRUGS WITH A WIDE MARGIN OF SAFETY.
Term
WHAT HAPPENS WITH THE DIFFERENT SHIFTS WITH DOSE RESPONSE CURVES?
Definition
A RIGHT SHIFT IS LESS POTENT (YOU NEED MORE DRUG TO GET A RESPONSE). A LEFT SHIFT IS MORE POTENT (LESS DRUG TO GET A RESPONE). UPWARD SHIFT IS MORE EFFICACIOUS (ABLE TO REACH MAXIMAL EFFECT). DOWNWARD SHIFT IS LESS EFFICACIOUS (UNABLE TO REACH A MAXIMAL EFFECT). IF THE CURVE MOVES ALONG THE DOSE AXIS (X), IT DEALS WITH POTENCY; IF IT MOVES ALONG WITH RESPONSE AXIS, IT DEALS WITH EFFICACY.
Term
RECEPTOR CONCENTRATION CAN CHANGE IN RESPONSE TO WHAT?
Definition
RECEPTOR CONCENTRATION CAN CHANGE (SOMETIMES RAPIDLY) IN RESPONSE TO REPEATED EXPOSURE TO AN AGONIST OR ANTAGONIST. THIS CAN BE RESPONSIBLE FOR A DIMINISHED OR EXAGGERATED RESPONSE TO A DRUG.
Term
WHAT DOES UPREGULATION OF RECEPTORS MEAN?
Definition
UP-REGULATION OF RECEPTORS OCCURS WHEN REPEATED EXPOSURE TO AN ANTAGONIST OCCURS, AND THE TISSUE IS ATTEMPTING TO RESTORE AN EQUILIBRIUM BETWEEN AGONIST AND RECEPTOR. EX. CHRONIC B-BLOCKADE WILL RESULT IN AN UPREGULATIONB OF B RECEPTORS. IF THE B-BLOCKER IT WITHDRAWN, CATECHOLAMINES (ENDOGENOUS OR EXOGENOUS) WILL BEIND TO THOSE RECEPTORS AND CAUSE AN EXAGGERATED, OR REBOUND AUTONOMIC EFFECT.
Term
WHAT IS DOWN REGULATION MEAN?
Definition
DOWN-REGULATION OF RECEPTORS OCCURS WHEN THERE IS REPEATED EXPOSURE TO AN AGONIST, AND THE TISSUE RESPONSE BY TRYING TO REDUCE THE AVAILABLE BINDING SITES. EX. REPEATED ADMINISTRATION OF ALBUTEROL IN AN ASTHMATIC PATIENT CAUSES DOWN REGULATION OF THE B2 RECEPTORS IN THE LUNGS, LEADING TO AN INABILITY OF THE DRUG TO CAUSE BRONCHODILATION
Term
DEFINE TACHYPHYLAXIS?
Definition
THE ACUTE PHENOMENON OF DESENSITIZATION OR DOWN-REGULATION OF RECEPTORS TO THE POINT OF DECREASED DRUG FUNCTION.
Term
DEFINE TOLERACE.
Definition
TOLERANCE IS THE EFFECT OF DOWN-REGULATION SEEN OVER A PERIOD OF TIME WITH CONTINUED ADMINISTRATION OF A DRUG. INCREASING DOSES ARE REQUIRED TO PRODUCE THE SAME EFFECT.
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