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Chap 22 – Digestive System

Explore peristalsis, digestive organ functions, hormone roles, chemical digestion processes, absorption, malabsorption, and common intestinal disorders. Learn about saliva composition, stomach functions, gastric pits, and small intestine features.

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Chap 22 – Digestive System

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  1. Begin reading Chap 22. Review Lecture notes & all practice activities. Chap 22 – Digestive System Learning Objectives Describe peristalsis. Identify the structures & explain the functions of each organ in the GI tract as well as accessory digestive organs. Be able to explain some of the hormones that act in the process of digestion, their site of production, and target organs. Explain chemical digestion of carbohydrates, proteins, lipids, and nucleic acids. Compare & contrast absorption with malabsorption regarding nutrients. Be familiar with numerous intestinal disorders discussed in class.

  2. Where It All Begins When you were younger, did you ever hear something similar to this? “Now, chew your food carefully BEFORE you swallow…” (What do you think the reasoning was behind that statement?) Swallowing video: http://video.google.com/videoplay?docid=4375530805602416900

  3. Food Moves Down the Esophagus into the Stomach via Peristalsis Peristalsis = __________________________? *NOTE: Peristalsis is so strong that once food or liquid is swallowed, it will reach your stomach even if you stand on your head!

  4. Digestion Begins in the Mouth • __________ – chewing (_________) & tooth action breaks apart food • _________ – saliva in mouth begins digesting ____; forms soft bolus (food ball) Research Item – Take a minute to check it out! What is Saliva composed of? Read the 2 paragraphs entitled the Composition of Saliva”, page782. Note your findings to share with the class.

  5. Getting to Know Your GI Organs Instructions: Match the functions with the intestinal organ. Write only the letter of the answer. Reference, pg 810.

  6. GI Tract & Primary Organs, pg. 773 • Label your practice diagram (except for the 3 “crossed out” structures).

  7. PREDICT • To be presented in class

  8. Stomach Gastric pits • To keep from digesting itself, the stomach has a ______ _______ with: • A thick coat of bicarbonate-rich mucus on the stomach wall • Gastric glands that have cells impermeable to HCL • Damaged epithelial cells are _______ replaced Gastric pits in the mucosa of the stomach secrete HCL; lined with chief cells that secrete pepsinogen (Protein digesting enzyme)

  9. Problem: Tummy Trouble A patient is complaining of gnawing upper abdominal pain that appears 1-3 hours after eating. The patient mentions that they seem to feel temporarily better after eating again. (NOTE: This has been ongoing for at least 4-6 months) What might be the problem? What is the possible cause?

  10. What Does the Stomach Do? http://video.google.com/videoplay?docid=3349901498863881080&q=stomach+view+on+endoscope&total=9&start=0&num=10&so=0&type=search&plindex=0 • The stomach: • Holds ingested food like a _____ _______ (6-10 inches in length) • Degrades this food both _________ (mixing & churning) and __________ • Delivers chyme to the small intestine • Begins ______ digestion with ________ • Secretes intrinsic factor required for absorption of vitamin B12 • Sends liquids onward to the small intestine; will retain solids until they are broken apart

  11. Stomach 101 • Label your practice diagram – ONLY structures circled in red.

  12. I Can’t Believe I Ate The Whole Thing • Stomach usually empties __ hours after eating • A meal high in fat may take up to __ hours • ___ _______ meal empties quickest (which is why you feel hungry again)

  13. Review 1. Saliva begins digesting ________ in the mouth? 2. Chief cells in the stomach mucosa secrete ________________ which act on _______? 3. Anatomical curve taking food ‘downward’ away from the stomach and into the small intestine?

  14. Small Intestine & Associated Structures • Body’s most major digestive organ - accomplishes virtually all ___________ of liquids & nutrients - as chyme enters the duodenum: Carbohydrates and proteins are only partially digested No _____ digestion has taken place - has an extensive surface area that is made even more vast by _____ & ________________

  15. Villi & Microvilli continued… Label your diagram (pg. 800) with the following: villi, microvilli, lacteal, intestinal crypt, duodenal glands

  16. Associated Organs Small intestine completes digestion with the help of __ other organs

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