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Physiology exam 4 digestive system

Lipase digests proteins lipids active only in low ph

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Unformatted text preview: al lipase: digests proteins, lipids. Active only in low pH. doesn't digest fats in mouth because does not work in neutral pH c. Digestion in the mouth Carbohydrates some carbs digested from salivary amylase Proteins & Lipids no fat or protein digestion occurs in the mouth d. Absorption in the mouth digesting some carbs but no significant absorption of any nutrient in mouth e. Motility in the mouth as we chew we use our tongue to push food to back of mouth and swallow motility largely done by tongue here. VI. ESOPHAGUS tube that connects mouth to stomach. all conditions that exist in mouth carry on to esophagus salivary amylase active all the way down esophagus. Using peristalsis, usually aided by gravity. what makes it possible to drink water upside down. food is probably at its firmest right here. Leads to relatively large amount of stretch and large amount of contraction from peristalsis at lower end we have Lowest Esophageal Sphincter (LES) separates esophagus from stomach. keeps conditions of esophagus and stomach separate. Heart burn and acid reflux caused by LES not working properly VII. STOMACH 1. distensible pouch between esophagus and small intestine 2. stomach wall rugae: roughness of stomach, sand paper covering, as food is ground up, reduce food to paste gastric glands: secrete specific things 3. role in digestive functions a. Secretion in the Stomach Mucous from goblet cells protects the stomach lining Pepsinogen inactive form (from chief cells) Converted to pepsin at low pH most times secrete where it won't be activated, pepsin is first enzyme to help digest proteins HCl from parietal cells 2 roles: a. denatures proteins (not digestion) b. activates enzymes, lowers pH (pepsinogen to pepsin) Gastrin released to how much food is there, more food more gastrin, stimulates parietal cells and stimulates chief cells has to do with how much stretch in the stomach. Histamine also stimulates parietal cells. spicy foods will increase histamine. (link between people with ulcers avoiding spicy foods) VII. STOMACH (cont.) b. Digestion in the Stomach Carbohydrates none…why? salivary amylase denatures in pH of stomach Proteins partially digested by pepsin Lipids secreted lingual lipase is activated by low pH in stomach 10-30% of fat digestion is due to lingual lipase "pooling" in stomach c. Absorption in the Stomach nutrients are NOT absorbed in the stomach water, alcohol, and aspirin ARE absorbed here d. Motility in the Stomach Storage - holds food until digestion proceeds and intestines ready to receive it Mixing - waves of contraction churn food with HCl, lingual lipase & pepsin Gastric Emptying - squirts liquified food into the small intestine VIII. SMALL INTESTINE (Part I) longest part of the GI tract (~12 feet long) 1. several sections: duodenum, jejunum, ileum duodenum: the first foot, jejunum the next 4 feet, ileum the last 7 feet 2. structure of SI walls net result of foldings and projections SI surface area= 250 square met...
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