-
Asked by anon-252014 to Yewande on 19 May 2020.
Question: what exactly causes anaesthesia
- Keywords:
-
Yewande Oyekenu answered on 19 May 2020:
Anesthesia is a state of unconsciousness. This is created artificially by drugs called anesthetic agents. You are put to sleep so you don’t feel the pain of surgery
Comments
Kelly commented on :
Just to add on to Yewande’s answer, anaesthesia can be local or general. Local anaesthesia is when a particular part of the body is numbed. Patients are awake but can’t feel pain where the drugs have been used. Local anaesthesia is typically used for minor medical procedures like getting a mole removed or getting a cavity filled at the dentist.
General anaesthesia makes a patient unconscious. This is kind of like being in a deep sleep – they can’t feel or remember anything that happened. General anaesthesia is used for more serious surgeries, like heart surgery.
Drugs for both types of anaesthesia work by interrupting signals to the brain, and local anaesthesia is much more common than general.
Luke commented on :
General anaesthetics generally work but suppressing activity in the parts of the brain that are important for keeping us awake and alert. The anaestheitc agent generally decreases the activity of nerve cells in these parts of the brain, causing us to slip into unconsciousness.
When we are conscious, the brain is very interconnected, meaning that different parts of the brain are talking to each other all the time in a network, which is thought to be responsible for consciousness/awareness. And of course, these interconnections are important for us being able to behave, think, feel, etc. Brain imaging studies have shown that when someone is anesthetised, the connections between different parts of the cortex (that’s the largest part of the brain; the outer region that has the folded appearance you see on pictures of the human brain) are weakened. This is thought to be key to making someone unconscious and being unable to perceive pain or any other sensation, such as vision, during anaesthesia.
——————-
Like Kelly said, local anaesthetics don’t make someone unconscious. Instead, they work by suppressing the activity of nerve endings in, for example, your skin. The drug lidocaine is an example of a local anaesthetic, which works by blocking a protein found in nerves called a ‘sodium channel’. This prevents the nerve cell being activated by painful stimuli, stopping any pain signals being sent from the anaesthetised region to the brain.
James commented on :
One more thought is that although we pretty much understand how local anaesthetics block pain signals from going to the brain, we really don’t understand very well how commonly used general anaesthetics work.
A general anaesthetic is a combination of medicines, which will be given in different doses and through different ways that are decided by a very experienced specialist doctor – an anaesthetist. Usually one medicine is given to help dampen down the parts of the brain that respond to pain – you might have heard of morphine. This is a very strong painkiller.
At the same time, another medicine to make you fall asleep and not remember things will be given – often this is a medicine called propofol. This seems to change the brain function to block awareness and increase sleepiness, although at a molecular level we don’t really know what things it does that are important.
Lastly, the anaesthetist will often (although not always) give a medicine to help block signals from the brain to the muscles of the body. This makes certain operations easier so that the surgeon doesn’t have to worry about any muscle movements or tension that can occur even during unconsciousness and cause complications. This is called a muscle relaxant. Importantly, if this is given the anaesthetist will need to be ready because it will also stop the muscles that allow breathing to occur from working. A special machine called a ventilator will be needed to allow the patient to keep breathing whilst the muscle relaxant works. However, don’t worry – muscle relaxants aren’t permanent and some only work for a short period. Part of the anaesthetist’s job is picking the right drug that will work for the right amount of time for the surgery.