Tham khảo tài liệu 'saladin anatomy and physiology the unity of form and function episode 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 25. The Digestive System I Text Saladin Anatomy Physiology The Unity of Form and Function Third Edition The McGraw-Hill Companies 2003 Chapter 25 The Digestive System 975 Mesocolon Tenia coli Ileum Cecum Appendix Rectum Anal canal a Sigmoid colon Ileocecal valve Ascending colon Epiploic appendages Transverse colon Superior mesenteric artery Haustrum---- it 1 Rectal valve Anal canal Hemorrhoidal veins Levator ani muscle Internal anal sphincter External anal sphincter ------Left colic flexure -----Descending colon External anal sphincter Chapter 25 b Figure The Large Intestine. a Gross anatomy. b Detail of the anal canal. Which anal sphincter is controlled by the autonomic nervous system Which is controlled by the somatic nervous system 25. The Digestive System I Text Saladin Anatomy Physiology The Unity of Form and Function Third Edition The McGraw-Hill Companies 2003 Chapter 25 976 Part Four Regulation and Maintenance Microscopic Anatomy The mucosa of the large intestine has a simple columnar epithelium in all regions except the lower half of the anal canal where it has a nonkeratinized stratified squamous epithelium. The latter provides more resistance to the abrasion caused by the passage of feces. There are no circular folds or villi in the large intestine but there are intestinal crypts. They are deeper than in the small intestine and have a greater density of goblet cells mucus is their only significant secretion. The anatomical features of the digestive tract from the large intestine to the anus are summarized in table . Bacterial Flora and Intestinal Gas The large intestine is densely populated with several species of bacteria collectively called the bacterial They ferment cellulose other undigested carbohydrates and fats and synthesize B vitamins and vitamin K which are absorbed by the colon. This vitamin K is especially important because the diet alone usually does not provide enough to ensure adequate blood clotting. The average person
