The brain naturally controls pain, we can begin to
The brain has a couple of methods through which it can naturally control pain. One of these methods is the descending pathway. After the pain signal has been sent from the nociceptors to the spinal cord, it goes up the ascending pathway to the brain, which responds by sending a signal down the descending pathway. This pathway goes through the periaqueductal gray (PAG) and is passed on by the rostral ventromedial medulla (RVM) until it reaches the spinal cord1. Here, the signal from the descending pain pathway inhibits the ascending pain pathway from the nociceptors; stopping the signal from reaching the brain, and so acts as analgesia2 .The descending pathway has two methods for inhibiting the signal – a direct path, and an indirect path.The direct path goes from the brain down to the synapse between the ascending pathway and the A? or C nociceptor nerve fibres and releases neurochemicals that inhibit pain, such as serotonin, into it, inhibiting the pain signal. The indirect pathway, on the other hand, branches off from the descending pathway and activates a different neuron, whose job is to then inhibit the pain signal by releasing inhibiting neurochemicals into the synapse. The end result of both pathways is then same, in that the pain signal is modulated by neurochemicals in the synapse.The other method through which the brain can control pain is by releasing neurochemicals known as endogenous opioids. These are made by several regions of the brain, including the RVM, and activate receptors in the amygdala and the thalamus. As these are both part of the medial pain system, their activation reduces can reduce the perception of pain for the subject. There are several types of endogenous opioids, including endorphins, enkephalins (which are the type the RVM produces), dynorphins, and endomorphins. These act on the opioid receptors throughout the brain, including those in the PAG, to help naturally control the pain.3Through study of how the brain naturally controls pain, we can begin to build up an understanding of what we can do to assist in controlling the pain. Currently, the main form of this is through analgesic drugs and pain medication. There are two types of analgesic drugs – opioid analgesics and non-opioid analgesics.Non-opioid analgesics are generally over-the-counter pain medication, such as aspirin, ibuprofen and naproxen. These work by acting on the site of the pain, where damaged tissue released enzymes that stimulate the local pain receptors. The non-opioid analgesics interfere with these enzymes and help to reduce inflammation and pain. However, they can also have adverse effects, specifically in the liver and kidneys, and prolonged use can cause gastrointestinal discomfort and bleeding.Opioid analgesics, on the other hand, are medications such as morphine and codeine. They act on the synapses in across the CNS, binding to the natural opioid receptors, inhibiting the ascending pathways and activating descending pathways. The disadvantage of these opioids is well known – they are highly addictive and easy to overdose. As a result, these are generally reserved for higher levels of pain where immediate relief is required, such as broken bones.