Heroes Not Zombies

Our blood vessels are a hugely important part of our bodies. I suspect most of us think of our blood vessels (arteries, veins, capillaries) as a kind of complex tubing. To the naked eye, blood vessels certainly look like tubes, or pipes, and their key function seems to be to provide channels to move the blood around our bodies.
But let’s look a little closer. Lining these vessels, on the inside, is a very, very thin layer called the endothelium. It is only a few nanometers thick (I know. It’s not actually easy to visualise something that thin). This is a fascinating, living, constantly changing tissue.
To fight infections, the body has to get specialised cells, leukocytes, to the right place. The endothelium co-operates with these cells by allowing them to pierce holes in it so they can pass through to the target area. However, a lining with holes in it would be a disaster for health, so the endothelium has to repair itself immediately. Researchers continue to learn just how it does this.
It’s now been discovered that the healing response involves an interplay of quite astounding behaviours and abilities. The whole process can be observed using electron microscopes which show how a leukocyte can pierce the endothelium, and over a ten minute period up to seven leukocytes can pass through the opening before it is completely sealed up.
The healing of the holes involves a change in the cells which make up the endothelium. In response to a loss of tension in the wall, the cells grow tiny little foot-like structures, lamellipodia, and actually move towards the hole to seal it up. The whole process requires the production of proteins which produce “reactive oxygen species” (ROS), such as hydrogen peroxide.
ROS chemicals have a bad name. High levels of ROS seriously damage cells, and are implicated in a wide range of problems, from heart disease to cancer and even aging. However, in much smaller amounts, they are the key to body defences and healing. This phenomenon is an example of hormesis where a small amount of something has an opposite effect to a large amount of the same thing. The large amount is damaging, whilst the small amount is healing.
I don’t know about you, but I find it exciting and astonishing to think of all this activity going on inside me body! All these incredible, responsive, detailed healing systems involving tissues which are made of individual cells which can grow feet and move, to amazingly complex feedback systems controlling the production and removal of an enormous range of chemicals, getting just what’s needed to the right place at the right time.
I don’t really understand why the model of a human body as a machine is so popular – it’s so wrong! We are a complex living community of cells who are in constant communication with each other to mutually support and enhance their existence.
This is what integration looks like.
This is what a complex adaptive system looks like.
A living community.