Sometimes people still have pain even though they are using non-opioid medicines like NSAIDs or steroids that you learned about in the last module. This pain may be severe with the score of 7-10, on a pain scale ranging from 0-10. In these cases, opioid medicines like morphine or hydromorphone, also known as Dilaudid, are needed to provide relief. I will now use the term opioids as a shortcut for all opioid medicines. Well, opioids are a large group or class of pain medications that are often used in the US and around the world to help ease moderate to severe pain. Some opioids were made in the lab only a few years ago, but naturally occurring ones like morphine and codeine are in the poppy flower and have been grown for thousands of years. Such pain relievers were first mentioned some 5,400 years ago. They were initially grown in the ancient Middle East in what is now Iraq, and traded with neighbors like Syrians and Egyptians. Since then, the growth and harvesting of opium poppy flowers has spread around the world. Opioids have a direct influence on the communication path between the area that is injured and the brain. Here is how this communication works. Think of an opioid receptor like a light switch. Sometimes the switch is turned on and we feel lots of pain. Sometimes, it can be turned off and we feel no pain. For example, the dentist uses lidocaine to numb your tooth when you have a toothache. In that case, pain receptors and other receptors are turned off, so you don't feel pain or anything else, you are numb. Some lights have more than just an on or off switch. They have a dimmer switch as well. This switch allows you to adjust somewhere between on and off to provide the amount of light that is just right for you. Similarly, opioid receptors can act like a dimmer switch. If light is pain, opioids can dim the light, so that you feel less pain. We humans naturally produce molecules or particles called endorphins which connect to and turn on opioid receptors. These receptors are found in the brain and other parts of the body. When they are turned on, the body experiences natural relief from pain, and the person can also experience a sense of well-being or euphoria. Exercise, sex, massage, and laughter are only some of the things that can lead to increased endorphin release in our bodies and the natural relief they provide. Opioids are drugs that connect to the same receptors as natural endorphins. The medical and scientific community thinks that most of the pain relief that opioids provide occurs when they connect to receptors in the brain and spinal chord, also known as the central nervous system. There are several types of opioid receptors, but only a few of them help with pain relief. The Mu, Alpha, and Kappa receptors are some of the most important ones for pain. When these receptors are turned on or activated by opioids, they make it more difficult for pain signals to reach the brain. Pain signals may be coming from damaged tissues like skin, bone, or muscle, or damaged organs like stomach or lung. At the same time, deactivated opioid receptors are making it harder for pain signals to reach the brain, they are also lowering the brain's response to pain signals from other parts of the body. All of this is happening in the part of the brain called the cerebral cortex. That's the part of the brain that lets us think and feel things. In addition to the cerebral cortex, opioids also act on another part of the brain called the limbic system. This part of the brain is commonly known for the fight or flight response. Opioid receptors that are switched on in the limbic system help us stay calmer when we are having pain. There are many things not yet understood about how opioid receptors, endorphins, and opioid medications work. One important thing we already do know though is how they can safely be given, and make life better for people suffering from pain. To learn more about this, join me in the next video.