Inflammation has been kind of a buzz word in the conversation about health, and you hear this word being used all the time when talking about disease processes. In fact, it’s hard to walk into a doctor’s office and not hear the word “inflammation” being use. But ask yourself this: what exactly is inflammation, and what is actually happening at the microscopic level? If you can’t answer these questions, then you must read on to gain a full appreciation of this basic but essential biological process.

Inflammation has always been talked about as a bad thing for the body, but the reality is, it’s actually a protective response to an injury in order to remove the cause of injury as well as the dead tissues that are casualties of the event. It’s hard for healing to take place when there is ongoing insult and a pile of dead cells are in the way of regenerating new cells. In other words, inflammation is necessary to set the stage for healing. But if it’s such a good thing, why are we always talking about stamping out inflammation? It turns out that the body sometimes goes overboard with the inflammatory response and ends up destroying everything in its path, including the healthy tissues along the way. This is when inflammation can become destructive because when it’s triggered, the effect can be pretty widespread; it’s a hammer and not a surgical scalpel.

When any cell or tissue in your body gets injured, inflammation immediately kicks in. There are five classic local signs of inflammation: heat, redness, swelling, pain, and loss of function. The first three signs are a result of what’s happening at the blood vessel level. When an injury occurs, blood vessels at the site of injury dilate which then increases the blood flow; this is what give rise to the redness and warmth seen in acute inflammation. In addition to dilation, blood vessels also become leaky, meaning that fluid and proteins typically found in blood can seep out of the blood vessel walls and get into the surrounding tissue bed. This is what give rise to the swelling seen in acute inflammation. As the fluid and protein components of the blood leak out, the red blood cells become more concentrated, so the blood at the site of injury becomes more viscous and flows slower. This phenomenon called stasis is important in aiding the next step in the process which is the arrival of the calvary, a.k.a. the white blood cells.

As the white blood cells arrive at the site of the injury, the slowing of the blood gives them time to squeeze through the cracks in the blood vessel walls and migrate into the surrounding tissues. Remember that the job of white blood cells is to help the body fend off foreign invaders. They do so by ingesting foreign materials and debris, destroying infectious agents, and produce antibodies. They do both the killing and the cleaning up, thereby clearing the way for healing to begin. Without the white blood cells, healing would be next to impossible, and infection can set in and spread throughout the body unchecked.

What happens after acute inflammation? It depends on what the initial injury is and how much collateral damage has been done. If the insult was short-lived and the injured cells can be replaced, than the result is full restoration to structural integrity and functional normalcy. However, if the damage is substantial and the cells cannot regenerate, then the result is scar formation whereby the injured cells are replaced by generic connective tissues; this process is also known as fibrosis. If the injury is ongoing, then acute inflammation can turn into chronic inflammation which is a similar process that involves slightly different groups of cells.

In a nutshell, inflammation is a necessary protective response that the body elicits when an injury occurs so that the body can contain and and remove things that might get in the way of healing. It is central to a lot of the disease processes that we talk about in health and medicine. Next time when you hear the word being used, hopefully it will be clear to you what that actually means for the body.