56 - Inflammation part 1 of 4

KYJ 56-  Inflammation (Series)

Part 1.
One of the common pathophysiological processes central to many acute and chronic diseases is Inflammation.

Being a process, like coagulation which we covered in a previous series, the inflammatory process has many steps, and complicated cocktails of chemicals are released from many tissues to activate, sustain or inhibit the process.

Inflammation (literally to catch fire) is a process mounted by the immune system to respond to fight pathogens, clean up cellular debris after injury or infection, and repair damaged tissue.

The classic symptoms of inflammation include:
Rubor = Redness (Erythaema)
Calor =  Heat
Tumor = Swelling (Oedema)
Dolor =  Pain.

Typically an inflamed body part is painful, red, hot and swollen. The redness and heat is why the Latin term inflammation (to catch fire) was used to describe the syndrome.

In this first of a few parts series, we will look at the end result and pathophysiology of these four symptoms, then in subsequent episodes of KYJ, I will take you through the cellular steps.

But first: the symptoms.
Red, hot, swollen.

Erythaema or redness off tissue is seen as a direct result of an increase of blood flow.  During an inflammatory response, blood vessels are stimulated by chemicals released by damaged cells, which widen the local blood vessels (vasodilation).  The result is higher blood flow which blushes the local tissues giving rise to the characteristic redness and increase of temperature in inflamed tissue (red and hot)

Oedema - swollen
If you missed our video on oedema, here is the link. (  http://youtu.be/sdWhUmUuWqc ).  Oedema is swelling of tissue.  As a consequence of the dilation of blood vessels I just discussed, it is reasonable to assume that an increase in blood flow would result in an increase in blood pressure in the local area.
Now the smallest blood vessels in tissues are capillaries; and these blood vessels are tiny- just a single cell thick and full of little holes that allow substances (nourishment and wastes) to leak from inside the capillary.  Water in the plasma of the blood leaks out of these holes (fenestrations), and this leakage is in part due to how high the pressure in the blood vessel is.  This pressure is called hydrostatic pressure.  The higher the blood flow through capillaries (hydrostatic pressure) the more they leak.   It is just like those green soaker garden hoses you probably once played under on a hot summer day.  If you turn up the tap (hydrostatic pressure) then it leaks more water, and capillaries are no different.  In locally inflamed tissue however, damaged capillaries have larger holes in them, so not only do they leak more plasma, but now they also leak a blood protein called Albumen.  Albumen is that plasma protein which acts like a water magnet holding volume inside the vast network of capillaries.  With out albumen you would leak uncontrollably.  As damaged capillaries lose albumen into the tissue spaces surrounding the blood vessel. The albumen, now in the interstitial space, attracts more plasma to leak from capillaries and surrounding cells.  The accumulation of fluid in the tissues is called oedema.

Next episode we look at the cellular chemicals and funky stuff like cytokines, and chemotaxis.

Check out my other vids on the YouTube channel called, funnily enough - ECT4Health.