Part12AnalgesicsGeneralConsiderationsPainClassificationPaingenerationandreactionsStimulationanddepolarizationofsensorynerveendingsPeripheralmechanismsofpainPeripheralmechanismsofpainPrimary&secondaryhyperalgesiaTheperceptionofsomaticpainTheperceptionandconductionofsomaticpainConductionpathwaysofpainThefMRIimagingofpainClassificationofanalgesics：Opioidanalgesics(centrallyacting)opiatessyntheticagentsAntipyretic,analgesic,andanti-inflammatorydrugs(peripherallyacting)aspirin,indomethacinOtherdrugs(forspecialtypesofpain)carbamazepine,atropine,nitroglycerin,etc.OpiumMorphine:Morphus,theGreekgodofdreams1.Pharmacologicaleffects(1)MechanismsofactionsActingoncentralopioidreceptorsreceptorsreceptorsδreceptorsMechanismsofmorphineactionsPeripheralmechanismsofmorphineactionsCentralmechanismsofmorphineactions:Paininhibitorysystem(2)CentralnervoussystemeffectsA.Analgesia：maximalanalgesicefficacy；relievingunpleasantsensation;euphoniaandpotentialofdependenceB.Depressionofrespiration:reducingthesensitivityofrespiratorycentertoCO2C.DepressionofcoughreflexD.Othercentraleffects:miosis,emesis(3)CardiovasculareffectsA.Posturalhypotension：Releasinghistamine;depressingCVScentersB.Increaseofintracranialpressures：RespiratorydepressionbrainCO2increasevasodilatationinthebrain(4)EffectsonsmoothmusclesA.GItract：Contispation:increasingrestingtoneofsmoothmusclesandsphincters,decreasingpropulsiveperistalsisandsecretions;Biliarytract：Oddi’ssphinctercontraction,increasingthepressureinthebiliarytractB.Respiratorytract：bronchoconstrictionC.Urinarytract：increasingvesicalsphinctertoneurinaryretentionD.Uterus(5)OthereffectsA.ImmunedepressionB.Endocrineeffects2.Clinicaluses(1)AnalgesiathepainofhighintensityandthepainofterminalillnessCautions:a)obscurethesymptomsandtheprogressofthedisease;b)dependenceoraddiction;c)biliarycolic:combinedwithatropined)notusedforlong-termifnoclearindications(2)Cardiacasthma(acuteleftventricularfailure)Asanadjuvant