Anesthesia
Surgery · Pharmacology · Neuroscience
Say it: an-us-THEE-zhuh
Anesthesia is a medically induced loss of sensation or awareness, produced by drugs called anesthetics, that prevents pain during surgery and other procedures.
UK spelling: anaesthesia
Definition
What is anesthesia?
Anesthesia uses drugs called anesthetics to block pain and, in some forms, awareness. Local anesthesia deadens feeling in one small spot, for example around a tooth or a cut, while the patient stays awake. Regional anesthesia numbs a bigger region, such as one limb or the lower half of the body, by injecting near nerves or around the spinal cord. General anesthesia affects the whole body, producing a reversible unconsciousness in which the patient cannot move or feel pain. Sedation, ranging from light to deep, relaxes a patient for shorter procedures.
Anesthetics work by interrupting nerve signaling. Local anesthetics block ion channels in nerve membranes so that pain signals cannot travel. General anesthetics, breathed in as gases or given into a vein, act on the brain, for example by strengthening inhibitory neurotransmitters or blocking excitatory ones, although their exact mechanisms are still not fully understood. Because general anesthesia can depress breathing and circulation, an anesthesiologist watches breathing, heart rate and blood pressure throughout.
Before effective anesthetics arrived in the mid-1800s, surgery was rare, rushed and agonizing. Their introduction made long and complex operations possible.
Word parts
Where does the word “anesthesia” come from?
- an-
- without, notGreek an-
- -esthesia
- sensation, feelingGreek aisthesis
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Related
Terms that go with it
- NeurotransmitterA neurotransmitter is a chemical messenger that a neuron releases at a synapse to excite or inhibit a target neuron, muscle cell or gland cell.
- Action potentialAn action potential is a brief, all-or-none reversal of the voltage across a nerve or muscle cell membrane that travels along the cell as a signal.
- ReceptorA receptor is a protein, on a cell's surface or inside it, that binds a specific signaling molecule and triggers a response in the cell.
- PharmacodynamicsPharmacodynamics is the study of what a drug does to the body: how it acts on its molecular target and how its effects vary with dose.
- Central nervous systemThe central nervous system is the brain and spinal cord, the part of the nervous system that takes in sensory input, integrates it and sends out commands.
- LaparoscopyLaparoscopy is a minimally invasive procedure that passes a thin camera, the laparoscope, through a small cut to view and operate inside the abdomen or pelvis.
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