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Unit 3: Animal Anatomy & Physiology Components of The Digestive System II Components of the Digestive System Organ Comments Function 10) small intestine duodenum: 1st part of the small intestine 1. finishes off chemical digestion for all nutrients produces intestinal fluid (more enzymes to digest all nutrients) receives secretions from pancreas & gall bladder mucus also protects from acidity & enzymes (3 parts) total of 6.2 m in length but only 2.5 cm wide jejunum & ileum: middle & last sections lined with finger-like villi peristalsis occurs 2. absorption of digested food into blood stream villi increase surface area 3. keeps food moving along Components of the Digestive System Small Intestine surface area of small intestine is greatly increased by: 1. lining of small intestine has folds 2. folds contain villi (finger-like projections) 3. villi contain microvilli total surface area of small intestine = area of professional tennis court Components of the Digestive System Small Intestine Duodenum Small Intestine Jejunum Ileum . Components of the Digestive System Organ 7) liver Comments Function large multi-lobed organ 1. stores excess glucose (A) filling most of the as glycogen abdominal cavity 2. filters out & breaks cirrhosis: down toxic compounds scar tissue forms from from blood damage by alcohol & (detoxification) drugs 3. makes bile breaks down large fat droplets into smaller ones (called emulsification) . Components of the Digestive System Organ 8) gall bladder Comments small sac under the liver (H) connected to the liver by the bile duct (J) gall stones crystallized bile J Function stores bile & sends it to the duodenum (1st part of the small intestine) . Components of the Digestive System Organ Comments 9) pancreas long feather–shaped organ sends pancreatic secretion to duodenum via the pancreatic duct Function 1. makes insulin 2. makes pancreatic secretion containing: enzymes which digest proteins, carbs & lipids . Components of the Digestive System Organ 13) large intestine (colon) (5 parts) total of 1.5 m in length & 6.5 cm wide Comments 1. caecum 2. ascending colon 3. transverse colon 4. descending colon 5. sigmoid colon feces: undigested waste contain enormous numbers of bacteria peristalsis Function 1. reabsorb water & minerals from digestive secretions & compact feces 2. produce vitamins B & K & help further digest waste 3. move feces along . Organ 14) rectum Comments muscular organ at the end of the colon 3 sphincters: 1. entrance of rectum 2. internal sphincter 3. external sphincter anus opening through which feces are egested when sphincters are relaxed Function 1. stores feces 2. control egestion Large Intestine (frames the small intestine) Shorter than small intestine Diameter is much greater Cecum First part of the large intestine, attached is the appendix Colon Main portion of the large intestine Water and dissolved minerals are absorbed Intestinal bacteria help break food down further Bacteria produce vitamin B-12 , K and some amino acids Large intestine completes the process! Any undigested material (feces) passes into rectum from the colon. Feces moves through anal canal and out the anus. Anus has a ring of circular muscle called the anal sphincter. Large Intestine Cecum Traverse colon Descending colon Ascending colon Cecum Sigmoid colon Rectum Anus Anal canal Large intestine endoscope: a narrow instrument with a camera at its tip placed inside digestive tract to view the inner lining can locate ulcers, polyps or tumours colonoscopy ENDOSCOPE VIDEOS DUODENUM DUODENUM VILLI NORMAL COLON ENDOSCOPE VIDEOS NORMAL COLON 2 PARASITIC WORM REMOVAL OF PARASITIC IN COLON WORMS IN COLON ENDOSCOPE VIDEOS COLON JAUNDICE DIARRHEA cause result danger bacterial infections, allergies, alcohol, food poisoning, etc. irritate intestinal walls peristalsis occurs too fast feces move through too quickly not enough water or minerals are reabsorbed feces remain very watery danger of dehydration loss of minerals (electrolytes) needed for body functions CONSTIPATION not enough fibre or water in diet to stimulate peristalsis feces move through too slowly too much water is reabsorbed feces become very dry more time for toxic substances & food additives to be absorbed hemorrhoids: blood vessels around anus are torn & bleed during egestion higher probability of colon cancer DIARRHEA treatment avoid foods that stimulate peristalsis (ex. fibre) drink plenty of fluids, especially those that contain electrolytes (ex. gatorade) CONSTIPATION eat high fibre food drink lots of water regular exercise (stimulates peristalsis) laxatives (ex. prunes – natural laxative) pharynx 1 epiglottis 4 esophagus 5 9 liver gall bladder bile duct small 14 intestine 19 2 3 salivary glands 6 stomach 7 cardiac sphincter 8 pyloric sphincter 12 pancreas 13 pancreatic duct transverse colon 22 ascending colon 21 descending colon 23 colon 20 10 11 duodenum 15 jejunum 16 ileum 17 18 ileo-caecal sphincter appendix rectum 25 tongue 24 anus 26 sigmoid colon Homework Small Intestine & Large Intestine Worksheet Page 188 # 1, 2, 5, 10 Magazine Ad from the 1930’s The Movement of Food Peristalsis – alternate waves of contraction and relaxation of muscles in the organ wall. Circular muscles push food ahead from contracting behind, when long. muscles are relaxed. Longitudinal muscles in front of food contract pushing food back, when circ. muscles are relaxed. Figure 10.15 The Movement of Food Rhythmic Segmentation – mix up partially digested food in intestine. Circular muscles push it back and forth while food stays in same place. Figure 10.16 . Components of the Digestive System Organ 1 2 3 Comments 11) ileocaecal sphincter ring of muscle at the end of small intestine & beginning of the large intestine 12) appendix tiny sac (3) found on the caecum (2) appendicitis: inflammation caused by bacteria (swells & could burst) Function keeps digested food in the small intestine allows more time for digestion & absorption function unknown believed to be left over from our evolutionary past Still the Small Intestine… Differ only slightly from the duodenum. Jejunum (2.5 m) Contains more folds and intestinal glands than duod. Breaks down remaining protein and carbohydrates Ileum (3 m) Fewer and smaller villi Absorbs nutrients Pushes undigested material into large intestine Components of the Digestive System Large Intestine