How Does Anesthesia Work?
Anesthesia was first used in 1846, by Dr William T.G.Morton in which he successfully demonstrated the use of Diethyl ether for surgery. In the old days, natural anesthesia were used such as opium-poppy, mandrake fruit etc. It is a medical treatment that prevents patients from feeling pain during surgery. Anesthesia can be of 3 types:
(1) Local
anesthesia – this
creates numbness only in one small area of the body.
(2) Regional
anesthesia - blocks pain in an area of
the body such as legs or
arms, mostly used during childbirth.
(3) General
anesthesia – makes you
fully unconscious. This is a combination of both intravenous drugs and inhaled
gases. It can have some side effect such as vomiting, nausea and
hallucination.
During
general anesthesia, the patient is supplied with inhaled gases.
These gases are a combination of both anesthetic
drugs and oxygen which goes to the lungs and then get mixed with the bloodstream which finally goes to
central nervous system (CNS).
In the brain, anesthetic drugs get attached to GABA
(gamma-aminobutyric acid ) receptors present in the limbic system, which control personal and emotional
feelings. GABA receptors are
actually found in
synapses of a neuron. They can be of 2 types: (1)GABAA receptors, (2)GABAB receptors.
These anesthetic drugs get attached to GABAA receptors and open the gateway allowing chlorine (negatively charged particles) to enter the cells of neurons, making them hyper-polarized. This inhibit neurons in transmitting electrical signals, which makes the brain lose all connections and thus we become unconscious. Though several studies have found that during unconsciousness our brain still remain active to some stimuli such as light and sound.
Emerging from unconsciousness is not so simple, the brain has to build up essential connections between them again, which happens in a certain order. Most basic and essential functions such as respiratory and digestive reflexes come back first, then comes the complex brain functions.
-Shyamendra Narayan Sinha
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