Anesthetics are depressant drugs that cause a total or partial loss of the sense of pain. The effect an anesthetic hason the body depends on several factors. What type of anestheticis used determines the effect along with the dosage and a person(or animals) body weight.The word anesthesia was first introduced by Oliver WendellHolmes in 1846 about four weeks after the first demonstration ofether anesthesia at the Massachusetts General Hospital. Etherwas the first type of anesthesia used and was demonstrated as ameans of allowing a patient to be unconscious and free fromsurgical pain. Stages of AnesthesiaStage one is known as analgesia and results from an increasein circulating endorphins. There is a mild depression ofcortical centers and this type of anesthesia is also known astwilight sleep.Stage two is characterized by a loss of consciousness. Itis a critical period because delirium and increased involuntaryactivity, as well as hypersecretion, can occur. It is best toget through stage one and stage two as quickly as possible andthis stage, along with stage one, are known as induction.Stage three is the stage of anesthesia known as surgicalanesthesia, and most surgical procedures are performed in thisstage. There is usually a loss of spinal reflexes and muscletone.Stage four is an undesirable stage and is characterized byrespiratory depression and other manifestations of overdose. Most general anesthetics are non-specific agents, meaningthat their activity depends on their lipid solubility rather thattheir structure. Inhaled and exhaled gas containing the agentsequilibrates with the lung tissue, and then with the blood. Inthe brain, the agent equilibrates between the blood and neuraltissue, depressing neurons and causing the pharmacologicaleffect.Types of AnesthesiaThough ether was the first type of anesthesia, there are nowmany different types. Ether, along with chloroform, are known asthe anesthetics from hell because th...
