Biology Within

Hypoxia means that the tissues of the body are not getting enough oxygen to meet their needs. Without enough oxygen, cells cannot make the energy they need to work. If the shortage is short and mild, they can cope and recover, but a severe or long-lasting shortage can kill cells and damage organs, especially the brain and heart.

Fibrosis is a slow buildup of tough, fiber-rich tissue inside an organ. It happens when the body keeps trying to repair damage that does not stop. Over time, this extra tissue crowds out working cells and leaves organs such as the liver, lungs, kidneys and heart stiff and less able to do their jobs.

The body heals a wound in a set order of steps. First it stops the bleeding, then it cleans the area, then it builds new tissue and new skin, and finally it makes the repair stronger. Most small wounds close within a few weeks, but the strengthening goes on quietly for a year or more.

Cells and tissues are damaged all the time, by things as ordinary as a cut, a burn or a short break in blood supply. Mild damage can often be undone by the cell itself, but severe damage kills cells. The body then senses the harm, clears away the dead cells and rebuilds the tissue, either with new cells or with a scar.