Gangrene is caused by what condition?

Gangrene occurs when body tissue dies due to a lack of blood supply, often coupled with bacterial infection. The primary cause is the inadequate flow of blood to the tissues, which may be due to conditions such as arterial blockage, diabetes, or severe injury. When blood flow is impaired, the affected tissues become deprived of essential nutrients and oxygen, leading to cell death. If bacteria invade dead or dying tissue, it can result in a severe infection that exacerbates the condition, potentially leading to more extensive tissue damage. Hence, the combination of loss of blood supply and bacterial invasion is what specifically characterizes the pathology of gangrene.

The other options refer to different conditions that do not directly cause gangrene. For example, the absence of pigment in the skin relates to congenital or acquired skin conditions but does not lead to tissue death or gangrene. Prolonged pressure on the skin can result in pressure ulcers, which may be a point of concern without blood supply but are not gangrene in themselves unless complicated by other factors. Exposure to extreme heat can cause burns, which lead to tissue damage, but again, this is a separate issue that doesn't typically categorize as gangrene unless it leads to complications involving loss of blood flow and subsequent infection.