Mental Floss

How Does Anesthesia Work?

The answer might be a little more complicated than you expect.

ByCaLea Johnson|
Nitrous oxide (also known as laughing gas) is a common anesthetic that only requires a mask over the mouth and nose.
Nitrous oxide (also known as laughing gas) is a common anesthetic that only requires a mask over the mouth and nose. | Shannon Fagan/GettyImages

You’ve likely been under anesthesia for different procedures, whether you were having a tooth removed or undergoing a major surgery. Everyone knows it puts you in a sleep-like state, but have you ever wondered what’s really happening inside your body?

Let’s start with how pain works. First, the pain receptors in the area of your body that has been injured release neurotransmitters, which are chemicals that send signals to the brain through the nervous system. The brain receives and processes those messages, then decides how to react and tells the body what to do. It all happens in a nanosecond.  

Although research has come a long way, we still don’t know much about how anesthesia works. What we do know is that certain types of anesthetics—there are several—function differently.

Local and regional anesthesia are usually injected into a group of nerves in a specific part of the body. The medicines travel to the brain and prevent neurons from receiving pain signals from the anesthetized body part. The patient remains awake and alert throughout the procedure, but feels no pain at the incision site. Local anesthesia is frequently used in small procedures, such as dental fillings or applying stitches to a cut, while those who have had an epidural during childbirth or a biopsy procedure have probably experienced regional anesthesia.

General anesthesia, whether inhaled or injected, affects electrical signals in the entire nervous system. It calms the neurons’ activity in the brain so certain parts of the organ stop “talking” to each other while the medicine is being administered. Patients become immobile, unconscious, and unaware. Scientists aren’t exactly sure how this happens, but they know general anesthetics bind with GABA receptors in the neurons to block pain signals.

Anesthesiologists often administer general anesthesia when someone needs an invasive procedure, such as major surgery, so the patient is completely out during the event.

Sedation anesthesia is used for minimally invasive surgeries (like broken bone repair or to diagnose abdominal issues). It involves light or moderate sedation via an IV so that the patient breathes on their own and remains awake in a calm and pain-free state.

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