intestinal villi. intestine lining. microscopic capillary. human intestine. concept of a healthy or diseased intestinal

absorption absorptive bacteria belly bile bowel cancer care cells cholesterol closeup colon concept digestion digestive duodenum enterocytes enzymes epithelial epithelium gastric gastritis gastrointestinal gut health helicobacter histology intestinal intestine intestines lining medical medicine microbestract microscopic microvilli minerals mucosa nutrients nutrition small stomach tissue tract ulcers villi villus