9. Reflexes in the colon and rectum Mass movements + + Food in stomach Food in duodenum Faeces Defaecation reflex Colon rectum anus Ach Spinal cord IAS EAS FAECES + Distention - VIP ATP + - Pudendal nerve
10. The Defecation Reflex: Summary Removes undigested faeces from the body. Stretch receptors in GIT wall detect distension of rectum. Parasympathetic reflex causes contractions of the sigmoid colon & rectum + relaxation of internal anal sphincter. External anal sphincter (under voluntary control) consciously relaxed if appropriate.
11. Secretary functions of GIT: Of 2 types: 1.Enzymes helping digestion. 2.Mucous for lubrication & protection of GIT mucosal surfaces from excoriation. Anatomical types of secretary glands: 1.Mucous glands: 2 types: a.single cell (goblet cells). b.complex cell mucous glands. 2.Crypts of Liberkhan: deeper & contains specialized secretary cells. 3.Deep tubular glands in stomach & upper duodenum secreting acid & pepsinogen. 4.Complex glands like salivary ,pancreatic & hepatic glands.
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15. CONTROL OF SALIVARY SECRETION cerebral cortex salivary centre in medulla autonomic nerves salivary glands salivary secretion pressure receptors and chemoreceptors in the mouth other inputs:smell& taste centers conditioned reflex simple reflex