|MadSci Network: Anatomy|
First, I would like to apologize for the delay in answering this question. It slipped through the cracks of my email network during some computer down time. We try not to have these things happen, but sometimes........ With that said, I am not sure that I understand your question. First, let me be clear that "steroid" is a general term applied to a large class of hormones made by your body . The different subclasses of steroids are related by their chemical structure, but their actions are quite different. I imagine that you are referring to the common medical practice of injecting the subclass of steroids called "corticosteroids" (e.g. hydrocortisone) into joints and other body parts to relieve pain, etc. Corticosteroids (normally made by the adrenal gland) have many effects in the body. One of them is to limit the function of the immune system, which is why they are called "anti-inflammatory", i.e. that they limit inflammation. Inflammation is a difficult concept to define, but you can think of it as the concerted action of the immune system at a tissue level. When different immune system cells come into an area of the body they create a characteristic set of changes that are important to processes like fighting infections. The four outwardly apparent hallmarks of these changes - pain, swelling, redness and heat - are largely due to the increased leakiness of blood vessels. Unfortunately, these same changes can also be damaging to the tissues, especially when they are happening out of control as in many disease states. So, injection of corticosteroids into tissues is done to limit the inflammatory response that is occurring at that local site, i.e. to limit the activation of the immune cells. In this way, high local concentrations of steroids can be achieved without having to expose the entire body to potentially harmful amounts of steroids. Note that the other main way to limit inflammation is to use drugs (e.g. Advil, etc) known as NSAIDs, which stands for non-steroidal anti-inflammatory agents. I hope that I have provided sufficient detail to answer your question. If not, or if I have answered the wrong question, please donít hesitate to ask again with a little more background of your problem. Tom Wilson, MD PhD
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