Bedsores, also called decubitus ulcers, pressure ulcers, or pressure sores, begin as tender, inflamed patches that develop when a person's weight rests against a hard surface, exerting pressure on the skin and soft tissue over bony parts of the body. For example, skin covering a weight-bearing part of the body, such as a knee or hip, is pressed between a bone and a bed, chair, another body part, splint, or other hard object. This is most likely to happen when the person is confined to a bed or wheelchair for long periods of time and is relatively immobile. Usually, mobile individuals, when either conscious or unconscious, will receive nerve signals from the compressed part of the body and will automatically move to relieve the pressure. Pressure sores do not usually develop in people with normal mobility and mental alertness. However, people compromised through acute illness, heavy sedation, unconsciousness, or diminished mental functioning, may not receive signals to move, and as a result of the constant pressure, tissue damage may progress to bedsores in these individuals.