netter140

GASTROINTESTINAL PHYSIOLOGY

Smali Intestinc Structure: III

Mitochondria Tight junctions

■    Microvillus

■    Fat droplets

■    Pinocytolic vesicle > Microvilli cul off 'Terminal web

Fndoplasmic reticulum Interdigitation of cells (dstemae and lubules) _lnle,_tt.,_{luUr space}

Figurę 7.18 Epithelium of the Small Intestine

The villi are lined with a single layer of columnar epilhelial cells called enterocytes. The apical membranę of the enterocytcs contains numerous microvilli. The enterocytes are involved in absorption of nutrients and the secretion of fluid into the intestinal lumen. Inter-spersed among the enterocytes are goblet cells, which secrete mucus. The crypts of Lieberkuhn are located at the base of the vilł and are the site where activeły dividing cells are found. The newh formed cells migrate up the villus over the course of 3 to 5 days ar«: are slouglied into the lumen. The crypts also contain Paneth cells, which secrete the antibacterial enzyme lysozyme.