Small and Large Intestines

Small Intestines: General Structure Extends from pyloric sphincter to ileocecal valve 3 Parts Duodenum Fixed in position; low absorption Receives enzymes from accessory organs Jejunum Ileum

Special Features Villi, Microvilli, Plicae circularis – Increase Surface area Lacteal  lymphatic capillary Intestinal Glands Water to aid absorption; no dig. enzymes Brunner’s Glands  Mucus Alkaline; duodenum near stomach Enzymes embedded in mucosal lining Peptidases – proteins Sucrase, maltase, lactase  sugars Intestinal lipase

Large Intestines: General Structure Ileocecal Sphincter Cecum – Pouchlike structure @ proximal end Appendix – lymphatic tissue; appendectomy Colon – Ascending, Transverse, Descending, Sigmoid Hepatic & splenic flexures Rectum Anal Canal Internal anal sphincter (involuntary) External Anal Sphincter (voluntary)

Large Intestines: Functions Teniae Coli – bands of muscle that extend length of colon Haustra Mucus only significant secretion Formation of feces – indigestible material Absorption of water & electrolytes Peristalic rush – rapid contractions of sm. Intestines  diarrhea Intestinal Flora – bacteria Cellulose breakdown  Vitamin K, B12, thiamin & riboflavin Flatulance