Small bowel mucosa is a term used to describe the specialized tissue that covers the inside of the small bowel. The small bowel is a long, hollow organ and part of the digestive tract. It starts at the end of the stomach and ends at the colon (large bowel). The small bowel mucosa is made up of specialized epithelial cells that connect together to form glands and a thin layer of connective tissue called the lamina propria. Very small finger-like projections, called villi of mucosa, stick out from the inner surface of the small bowel. These villi allow the small bowel to absorb nutrients by increasing the surface area of the small bowel.
A wide variety of medical conditions can involve the small bowel mucosa. For example, gluten-sensitive enteropathy, or Celiac disease, damages the cells in the mucosa of the small bowel. Doctors will often take a sample of tissue in a procedure called a biopsy to look for this condition or to monitor response to a gluten-free diet. Patients who take non-steroidal anti-inflammatory medications, or who are infected with the bacteria Helicobacter pylori, may show changes in the small bowel called peptic duodenitis. Some types of cancer, such as adenocarcinoma and neuroendocrine tumours, also start from cells in the small bowel mucosa.