UG Anatomy syllabus PPT on Intestine.pptx

Intestine.pptx

1. SMALL AND LARGE INTESTINE

2. INTRODUCTION Longest part of digestive system Long & less distensible – Small intestine Shorter & more distensible- Large intestine Function- digestion, metabolism & stored for expulsion. Suffers –bacterial infection like typhoid, tuberculosis. parasitic infection like round worm, tape worm etc, Diarrhea & Dysentery.

3. SMALL INTESTINE EXTEND ; Pylorus to ileoceacal junction Measurement : 6 meters long, greater in male than in female & greater in cadavers Divided into : Upper - fixed part- DUODENUM - 25cm long. Lower – mobile part – long convoluted tube Upper 2/5 th of mobile intestine are known as JEJUNUM & lower 3/5 th known as ILEUM. Structures adapted for digestion & absorption.

4. RELEVANT FEATURES Large surface area: for absorption of digested food very large surface area is required. This is achieved by: Greater length of intestine Presence of 1. Circular folds of mucous membrane, 2. Villi & 3. Microvilli .

5. 1.Circular folds of mucous membrane/ plicae circulares /valve of kerking Forms complete or incomplete circles. Permanent & not obliterated by distention Begins in the 2 nd part of duodenum & become large & closely set below level of the major duodenal papilla. They continue to be closely set in the proximal half of the jejunum but diminish progressively in size & number in distal half of jejunum & in the proximal half of ileum.

6. Almost absent in the distal half of the ileum. Apart from increasing the surface area for absorption , the circular folds facilitate absorption by slowing down the passage of intestinal contents.

7. II. Intestinal villi Finger like projection of mucous membrane, visible to naked eye. Valvety appearnce Large & numerous in the duodenum & jejunum but smaller & fewer in the ileum. Vary in density from 10-40 per square millimeter & about 1-2 mm long. Increases the surface area about 8 times

8. Microvilli Villus is covered by a layer of absorptive columnar cells, surface of these cells has a striated border seen under the electron microscope

9. Intestinal Glands or Crypts of Lieberkuhn Simple tubular glands distributed over the entire mucous membrane of jejunum & ileum. Open by small circular apertures on the surface of mucous membrane b/w villi Secretes digestive enzymes

10. Epithelial cells of glands show high level of mitotic activity, proliferated cell gradually move towards the surface to be shed from tips of villi . Complete epithelial lining of the intestine is replaced every 2-4days.

11. Lymphatic follicles Two types Solitary lymphatic follicle - 1 to 2 mm & are distributed throughout the small & large intestine. Aggregated lymphatic follicles/ Peyer’s patches - circular or oval patches, varying in length 2-10cm & containing 10-200 follicles. Ileum- largest & most numerous Distal jejunum- small circular & fewer Placed- antimesentric border Ulcerated in typhoid fever

12. Both most numerous at puberty , diminish in size & number thereafter. Each villus has a central lymp vessel called a lacteal – plexes in the wall of gut- regional lymph nodes

13. Arterial supply Jejunum & ileum – jejunal & ileal branches of superior mesenteric artery Vasa recta distributed alternatively to opposite surface of gut – run b/w serous & muscular coat reaches villi .

14. Lymphatics Mesentric lymph nodes

15. Nerve supply Symphathetic – T9-T11 Parasymphathetic - vagus Enteric nervous system