CBSE Class 9 Answered
Ulcer is a lesion or sore on the skin or mucous membrane characterized by the disintegration of the tissue and often the discharge of pus. It is usually accompanied with inflammation and necrosis (dead tissue).
Ulcers are most common on the skin of the lower extremities and in the gastrointestinal tract, although they may be encountered at almost any site. The diverse causes of ulcers range from circulatory disturbances or bacterial infections to complex, multifactorial disorders. The superficial tissue sloughs, leaving a crater that extends into the underlying soft tissue, which then becomes inflamed and is subject to further injury by the original offender or secondary infection. Without the protection of an intact surface, ulcers from any cause can become deeper due to injury or infection.