Each defensive wave of fighters brought to the attack scene by the exudate is carefully orchestrated by a command-and-control structure housed in the immune system and staffed with excellent communicators, strategists, spies and analysts. They’ve received information from the first responders, describing what the attack looked like and what is required to fight a good fight. The immune command-and-control center sends out messenger cells called cytokines that are used to signal when to start inflammation and when to shut it down. Cytokines also help communicate how strongly to ramp up the attack (how much inflammation is needed).
Blood vessels leading away from the injury site are essentially sealed off, preventing the loss of cytokines and white blood cells and other healing molecules from the scene, as well as making escape more difficult for various microbes, etc. The area around the injury now has only one door open and the exit door shut. At this point the injury site is filled up with cells that can work to repair and rebuild tissue, as well as destroy infection.
This process can occur in minutes or hours and can last for days if necessary. It depends on how severe or lengthy the attack is.
Swelling is created to help
While exudate is creating swelling to trap the attackers, the special force teams are getting into formation. Complement is a group of proteins carried in the exudate that act together to initiate inflammation. It’s like a squad of Navy Seals. Specialized proteins link together in groups of nine. The ring-like link formed by complement is called a membrane attack complex, or MAC. I like to think of it as the MAC attack. MAC controls the movements in and out of the cell of substances like calcium ions, which contribute to cell death.
Other specialty fighters appear
Other specialty fighters appear. Lymphocytes (among them T cells and B cells) arrive to more specifically target enemy cells. Macrophages and monocytes march in, devouring enemy cells and assisting the body in even more specific attacks against the invaders. The immune system analysts take notes about microbes involved in the attack, updating the immune system’s memory files so if that particular kind of attack ever comes again in the future, a ready-made response can be more quickly deployed.
Then the body’s repair job is finished
Eventually when the repair job is finished and infection is no longer an issue, the body signals for the exit door to open. Then all the exudate—that healing fluid bursting with pro-inflammatory cytokines and macrophages—is released. Now that it’s no longer needed, the swelling goes away.
During healing, the body uses pain signals to help you act in ways that are protective to the injured tissue.
What we’ve seen so far in this military analogy are all the signs of acute inflammation (swelling, heat, redness and pain). Now you likely better understand the parts they play in healing. Of course, how well your body can achieve its ultimate goal of healing depends on how well your cells are able to regenerate, and what kinds of injuries that were sustained. Needless to say, this is dependent on your overall health.
Swelling, pain and warmth is useful in healing
I think it’s fascinating how swelling, pain and warmth are so very useful in healing, and not just an annoying part of the injury trauma. Often we mistake good health as equivalent to having no swelling, no heat and no pain in our bodies. So instead of addressing the causes of these signs of healing, we seek to get rid of the symptoms. We reduce swelling, heat and pain with anti-inflammatory medication; we lower fevers, we take pain relievers, etc. The natural bodily defenses, however, can be crippled by these misguided attempts. The body’s best defense troops were using inflammation to solve an injury problem, and now they have been artificially denied this method. It’s similar to the military’s being grounded and not allowed to fight back. Without inflammation, the body is simply not as capable to efficiently kill microbes or heal from injury.
Stopping the symptoms isn’t always helpful
When we learn to better understand what the body is doing, we see that some of our conventional “stop the symptoms” responses to problems (for example trying to immediately reduce swelling or lower a fever) may not always be as helpful as we think.