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Small and Large Intestine Histology Histology > Digestive System > Digestive System SMALL INTESTINE: GENERAL FEATURES Includes the duodenum, jejunum, and ileum (which can be remembered with the mnemonic Don't Jiggle It) Wall Layers • Mucosa - Villi are finger-like extensions of mucosa - Covered in surface columnar epithelial cells, including absorptive enterocytes, from which microvilli extend into the lumen as a brush border. - Surface epithelium also secretes surface mucus for protection and lubrication. - Villi and microvilli increase surface area for absorption • Submucosa - Separated from mucosa by muscularis mucosae • Muscularis externa - Longitudinal and circular layers of smooth muscle - Innervated by enteric nervous system • Serosa Circular folds, aka, plicae circulares, (aka, folds of Kerkring) • Provide increased surface area for digestion. Recall that continued digestion of foods and absorption of nutrients are key functions of the small intestine. - Are most prominent in the middle region of the small intestine (largely absent in colon). Lacteals • Lacteals are the lymphatic structures of the small intestine that absorb lipids, and are in close association with the vasculature. Tubular intestinal glands/crypts • Further increase the surface area of the small intestine. • Paneth cells, which are not distinguishable here, reside at the base of the crypts; they secrete antimicrobial peptides 1 / 2 that protect enterocytes from bacteria. Goblet cells • Secrete lubrication SMALL INTESTINE: SPECIFICS Brunner's glands in submucosa of duodenum Peyer's patches - Aggregations of lymphoid tissues with a germinal center surrounded by a dome. Lymphoid tissues are present in all parts of the gastrointestinal tract (except the stomach), and are collectively referred to as GALT – gut-associated lymphoid tissue. Peyer's patches are most prevalent in the distal section of the small intestine and the colon. COLON The large intestine includes the colon, which is subdivided per its direction of travel within the abdominopelvic cavity, and the rectum and anus. Walls • Four layers, continuous with those of small intestine Tubular glands in mucosa • Abundant goblet cells The large intestine is responsible for absorption of water, salt, vitamins and minerals; though not visible in our sample, the glands are deeper than in the small intestine. Again, remember that the large intestine does not have circular folds. Images: Histology (Mark Braun, MD, & Indiana University: http://medsci.indiana.edu/c602web/602/c602web/toc.htm; http://www.indiana.edu/~anat215/virtualscope2/start.htm) Powered by TCPDF (www.tcpdf.org) 2 / 2.

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The Herbivore Digestive System Buffalo Zebra
The Herbivore Digestive System Name__________________________ Buffalo Ruminant: The purpose of the digestion system is to ______________________________ _____________________________. Bacteria help because they can digest __________________, a sugar found in the cell walls of________________. Zebra Non- Ruminant: What is the name for the largest section of Organ Color Key a ruminant’s Mouth stomach? Esophagus __________ Stomach Small Intestine Cecum Large Intestine Background Information for the Teacher Two Strategies of Digestion in Hoofed Mammals Ruminant Non‐ruminant Representative species Buffalo, cows, sheep, goats, antelope, camels, Zebra, pigs, horses, asses, hippopotamus, rhinoceros giraffes, deer Does the animal Yes, regurgitation No regurgitation regurgitate its cud to Grass is better prepared for digestion, as grinding Bacteria can not completely digest cell walls as chew material again? motion forms small particles fit for bacteria. material passes quickly through, so stool is fibrous. Where in the system do At the beginning, in the rumen Near the end, in the cecum you find the bacteria This first chamber of its four‐part stomach is In this sac between the two intestines, bacteria digest that digest cellulose? large, and serves to store food between plant material, the products of which pass to the rumination and as site of digestion by bacteria. bloodstream. How would you Higher Nutrition Lower Nutrition compare the nutrition Reaps benefits of immediately absorbing the The digestive products made by the bacteria are obtained via digestion? products of bacterial digestion, such as sugars produced nearer the end of the line, after the small and vitamins, via the small intestine. intestine, the classic organ of nutrient absorption.
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Vestibule Lingual Frenulum Tongue Hyoid Bone Trachea (A) Soft Palate
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6-Physiology of Large Intestine.Pdf
LARGE INTESTINE COLON MOTILITY Color index • Important • Further explanation 1 Contents . Mind map.......................................................3 . Colon Function…………………………………4 . Physiology of Colon Regions……...…………6 . Absorption and Secretion…………………….8 . Types of motility………………………………..9 . Innervation and motility…………………….....11 . Defecation Reflex……………………………..13 . Fecal Incontinence……………………………15 Please check out this link before viewing the file to know if there are any additions/changes or corrections. The same link will be used for all of our work Physiology Edit 2 Mind map 3 COLON FUNCTIONS: Secretions of the Large Intestine: Mucus Secretion. • The mucosa of the large intestine has many crypts of 3 Colon consist of : Lieberkühn. • Absence of villi. • Ascending • Transverse • The epithelial cells contain almost no enzymes. • Descending • Presence of goblet cells that secrete mucus (provides an • Sigmoid adherent medium for holding fecal matter together). • Rectum • Anal canal • Stimulation of the pelvic nerves1 from the spinal cord can cause: Functions of the Large Intestine: o marked increase in mucus secretion. o This occurs along with increase in peristaltic motility 1. Reabsorb water and compact material of the colon. into feces. 2. Absorb vitamins produced by bacteria. • During extreme parasympathetic stimulation, so much 3. Store fecal matter prior to defecation. mucus can be secreted into the large intestine that the person has a bowel movement of ropy2 mucus as often as every 30 minutes; this mucus often contains little or no 1: considered a part of parasympathetic in large intestine . fecal material. 2: resembling a rope in being long, strong, and fibrous 3: anatomical division. 4 ILEOCECAL VALVE It prevents backflow of contents from colon into small intestine.
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