HOW THE BODY HEALS

Part 1 – Inflammation

As a physical therapist, I was taught to look at the physical aspects of an injury. 

What was happening at the cellular level when the injury occurred? 

When tissue is damaged, there’s an inflammatory response in the body.

This is the first stage of healing.

And it’s a much needed stage not to be overlooked.

It begs the question, however, if it’s so important why are we instructed to:

1. Rest (avoid aggravating activities)
2. Ice (15 minutes every hour is recommended. Make sure to wrap the ice in a towel)
3. Compress: (if able)
4. Elevate the injured area

Well, it’s because we want control over how much inflammation occurs.  The more inflammation and swelling, the more potential for tissue damage to surrounding tissues. 

Research now supports if you ice a sprained ankle right away, the recovery time is shortened. There’s also evidence that supports chilling the body after a heart attack to minimize further damage, and relieving pressure in the brain after brain injuries, all works in helping with a more complete recovery.

INFLAMMATION (stage one of healing)

The process begins when blood comes in contact with our collagen (the connective tissues in the body). The body sets into motion a series of events designed to:

1. Stabilize the body and prevent further bleeding (stimulation of clotting factors)

2. Eliminate tissue damage

3. Stimulate repair

The initial response to injury is blood vessel constriction (5 to 10 minutes) followed by vasodilatation. We also see a lying down of fibrin (cross linking fibres or a natural bandage) over the wounded area. 

This would be like laying down a chicken wire over a hole in a chain-linked fence. It will help keep what’s inside from escaping or what’s on the outside wanting to get in from getting in – kind of like chickens in a hen house, with a sly raccoon lingering outside. 

CHEMICAL RESPONSE TO CLEAN UP

We have what are called mast cells located in our tissues. These cells when triggered release mediators (histamine and tumour necrosing factor or TNF) that start the inflammation process. Histamine triggers blood vessel dilation (vasodilatation) and increased permeability of the blood vessels, which allows more blood flow to the area and cells to get through the cell walls to the injured tissue better. When it comes to increased permeability, I think about it as making the doorway bigger to let the big guys out to help with the recovery response. 

INFECTION PROTECTION

These mediators call to action white blood cells called lukocytes which help defend against infection. These little guys travel to the injured area via the blood stream. I’ve often related this as calling 911 when you need an ambulance and getting not only the ambulance, but firefighters and police arriving at the scene. 

A tissue injury can make tissues look like a tornado ripped through your muscle or whatever soft tissue (ligament, tendon, muscles) that’s been injured. The emergency response team shows up and starts to co-ordinate the cleanup effort.

Another type of white blood cell called neutrophiles is predominating at the wound site for the first couple of days. These neutrophiles break down debris and bacteria (that can contribute to infection) and kill bacteria (using free radicals) and also cleanse the wound. Once these guys are done their job the monocytes (50 per cent is stored in the spleen as reserves) which become macrophages when they leave the blood stream at the injured site. These are the “big eater” cells in our bodies. Their role is to surround, break down and digest the neutrophiles.

I’ve always considered these guys the Pac-Men of the body (for those who grew up in the 1980s).  These macrophages also stimulate other lymphocyte immune cells in the body which will attack any foreign substances that may be in the area.

Macrophages are very important in wound healing. These are protein derived and attracted to the injured site by growth factor.

On a side note, one of the reported benefits of IMS (intramuscular stimulation) is the release of platelet derived growth factor, which can help stimulate tissue repair. 

The macrophage is a key player in moving the healing from inflammation to repair, but good repair occurs in the absence of macrophages (presence of macrophages delays wound contracture).  

There is also the release of cytokines, whose role is to control the function of other cells (like a messenger). These guys influence the leukocytes involved in inflammation and repair.

SIGNS OF INFLAMMATION

1. Redness: This is from the dilation of blood vessels in the area that’s required to help bring increased blood flow (carrying all the required white blood cells) to the site of injury. 

2. Warmth: From the increased blood flow to the area in addition to the release of certain chemical mediators.

3. Swelling: Otherwise known as edema occurs when fluid (exudates) accumulates outside of the blood vessels.

Contained within the edema or exudates includes substances that help with clotting (to prevent the spread of infection throughout the body), and antibodies that will attack foreign substances that might be present. 

4. Pain: associated with inflammation occurs because of pressure on pain sensitive structures, in addition to certain inflammatory chemical mediators in the system (serotonin, prostaglandins, bradykinin). 

Now that I’ve mentioned prostaglandins, you might as well know these are fatty acids in the body (unlike the lukocytes which are protein derived), that are responsible for increased permeability of the blood vessels (letting certain cells leave the artery which carries blood away from the heart, into the injured area). 

These fatty acids also help with clotting and create pain and warmth at the injured site. 

When you take an anti-inflammatory, you’re stopping the production of prostaglandins. 

Bradykinin (of the kinin system) contributes to pain and itching associated with inflammation. Its role in the inflammation process is thought to be in the control of the blood vessels.

SUMMARY

We need the inflammation response to happen in our bodies after an injury, but it needs to be contained. So continue to rest, ice, compress, and elevate as much as you can to help with the recovery process. 

Too much of a good thing can sometimes not be such a good thing.

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