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A Digestive Journey:

A Digestive Journey:. Part II. A series of “stations” along a subway. Accessory (Helper) Organs. Salivary Glands (previously discussed) Pancreas Liver Gallbladder. Accessory Organs. THE PANCREAS - lies behind stomach and extends laterally from the duodenum - finger shaped organ

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A Digestive Journey:

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  1. A Digestive Journey: Part II

  2. A series of “stations” along a subway

  3. Accessory (Helper) Organs • Salivary Glands (previously discussed) • Pancreas • Liver • Gallbladder

  4. Accessory Organs • THE PANCREAS • - lies behind stomach and extends laterally from the duodenum • - finger shaped organ • -15 cm in length • Function(s): • - secretes digestiveenzymes (pancreatic fluid)into the small intestines & hormones into the blood • bicarbonate ions NEUTRALIZE the HCl when entering duodenum • releases amylase into small intestine Enzyme Action:(all released into the small intestine) 1) lipase – digests fat 2) amylase – further breakdown of carbohydrates 3) trypsin – breaks down protein into short chains of amino acids

  5. Accessory Organs • THE LIVER • - second largest organ / roughly 1.5 kg • - two main parts: the right and left lobes • Functions: • - produces bile (emulsifies FAT into little fatty • globules) • - extracts absorbed nutrients or toxins from blood • - decomposes toxins (ie. Alcohol, drugs) • - key role in regulating body metabolism (homeostasis) • - manufactures many essential body proteins • - regulates the balance of hormones • regulates body cholesterol • stores excess glucose (in the form of glycogen) Enzyme Action: - high concentration of catalase enzymes that play key role in decomposing toxins (i.e. Alcohol).

  6. Accessory Organs • THE GALLBLADDER • “pear-shaped” muscular sac located under the right lobe of the liver • - connected to liver via hepatic duct Function(s): - collects and concentrates the bile that it receives from liver - releases bile to duodenum Hormonal Action: - gall bladder contracts in reaction to hormone cholecystokinin (CCK) to release bile into the duodenum.

  7. Station #4 – Small Intestine • The chyme enters the small intestines from the pyloric sphincter (opening at bottom of stomach) • Physical digestion and movement- muscle (longitudinal and circular)-Peristalsis and segmentation contractions • A long tube (5.75m) where chemical digestion is completed and nutrients from food are absorbed into the bloodstream • 3 sections: duodenum, jejunum, and ileum • Absorption - made of villi & micro-villi (cells which have long projections: increases the surface area for absorbing nutrients)

  8. Station #4 – Small Intestine Con’t 3 Parts  Duodenum, Jejunum, Ileum • DUODENUM • - receiving department (receives chyme from stomach) - • one inch tube • connected to stomach & Ileum • Function(s) • digestion and ABSORPTION of most nutrients • - mixes and propels food forward Enzyme Action: - see pancreas Hormonal Action: - Secretin to reduce acidity from food coming from stomach

  9. Station #4 – Small Intestine 2) JEJUNUM & ILEUM Enzyme Action: 1) peptidases- break down short chain of amino acids into individual amino acids 2) disaccharidases- breaks disaccharides into simple sugars Hormonal Action: - synthesis of melatonin= skin pigment

  10. Station #5 – Large Intestine (Colon) - about 1.5 m in length - divided into 3 parts: I. ascending II. transverse III. descending • Function(s): • - absorb water and some minerals • vitamin K and some B-complex vitamins are produced by resident bacteria. • - hold and compact the unabsorbed material from small intestine.

  11. Station #6 – Rectum & Anus • Rectum = 8 inch chamber connected to anus • Anus - 2 inches long, consists of pelvic muscle and two sphincters, surrounded by sphincter muscles • muscles relax to release stool (feces) • - muscles contract to keep stool in place Functions: Rectum - STORAGE of stool Anus – EXPELS WASTE from the body

  12. Disorders of the Digestive System • Appendicitis: appendix is inflamed, must be removed • Dysentery: colon is inflamed due to amoeba • Gallstones: stones form due to bile hardening (in gall bladder) • Gingivitis: inflamed gum tissue due to bacteria

  13. Reviewing – The Use of Cue Cards Take 10 cue cards (one for each “station” and accessory organ in the digestive system. FRONT of the cue card will represent the structure. - write the name of the organ - draw/sketch or print then glue on a labelled diagram BACK of the cue card will represent the functions. - types of physical & chemical digestion - specific functions - enzyme action - hormonal action QUIZ YOURSELF by: - putting the cue cards in order - having someone read one side of the card and you indicate what is on the other side. FRONT - Structure Station #2 – The Esophagus BACK - Function • Physical – peristalsis • Chemical – none • Functions • Moves bolus from pharynx to stomach • sphincters (esophageal & cardiac) prevent food from moving backwards. • Enzyme action – none • Hormonal action – none

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