Wounds and healing 1, Tissue regeneration or fibrosis

Wound healing occurs whenever there is injury to the tissues of the body. An injury describes an area of loss of continuity in any body tissue, this may occur as a result of trauma, infection or a pathological process. The mode of wound healing depends on the powers of regeneration a particular tissue possesses. The following are some examples at specific sites.

Liver

Liver is able to regenerate very well. For example, acute hepatic injury caused by viral hepatitis or toxin exposure, can regenerate completely restoring full form and function. However, chronic insults such as ongoing exposure to alcohol or hepatitis C virus, may result in the formation of collagen based scars and the development of cirrhosis. This latter process is associated with loss of functional liver tissue, so may progress to liver failure. This gives hope for heavy drinkers; liver function may be restored, sometimes after many years of abuse, as long as the person stops drinking before cirrhosis is established.

Kidneys

In the kidneys, epithelial tissues lining renal tubules may regenerate but whole nephrons do not. This means that mild damage to the kidneys will heal completely but more extensive injuries will result in scar formation. The glomeruli are the balls of capillaries within a Bowman's capsule and do not regenerate after injury. However, if one kidney is removed, the glomeruli in the other kidney enlarge to compensate.