Digestion 2

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Segmentation:

4/7/2013 1 Segmentation Ability to form little haustra (pouches) Like little mysterious fingers kneading bread Walls of gut have Longitudinal muscles (running length of gut) Circular muscles (rings) Relaxation of longitudinal muscles and contraction of circular muscles form a little pouch.

Stomach Emptying Time:

4/7/2013 2 Stomach Emptying Time Duodenum provides potent signals inhibiting emptying of stomach. Types of food (liquids > solids) Fatty, acidic, partially digested food in duodenum inhibits stomach emptying. Hormonally driven Secretin Gastric inhibitory peptide Cholecystokinin Cortex Fear Anxiety anticipation Stretching of the stomach wall elicits local myenteric reflexesemptying Change in pHemptying Longer food stays in stomach longer acid has to attack stomach

Small Intestine:

4/7/2013 3 Small Intestine Pyloric Sphincter (Sphincter III) between stomach and small intestine.

PowerPoint Presentation:

4/7/2013 4 Ulcers at the duodenum Factors Involved (Common predisposing factors) Hypersecretion of hydrochloric acid and hyposecretion of mucus. Smoking, alcohol, coffee, stress. Treatment of Ulcers First treatment give an antiacid Sodium bicarbonate Rolaids Tums Buffer acid Frequent meals Adding bulk to tie up acid Certain drugs to block formation of acids H 2 Antagonists block sites on parietal cells that histamine binds to. e.g. Tagamet (Cimetidine), Zantac Proton pump inhibitors e.g. Prilosec, Nexium Hazard of H 2 Blockers If you take too much tagamet You go into achlorhydria which means you don’t have enough hydrochloric acid There goes a lot of your digestion Acids breakdown the food so enzymes can digest it Certain enzymes only work at certain pH Block enzyme action Certain foods are fairly poisonous Acids will break them down into non-noxious state where they won’t hurt you

Intestinal Events Absorption:

4/7/2013 5 Intestinal Events Absorption Absorption All the final metabolites are absorbed Amino acids Hexoses Fatty acids and glycerol Two structures Villi Amino acids Some fatty acids Hexoses Lacteals Fatty acids Strictly fat absorption Increased surface area in projecting villi enough to cover a nine hole golf course Some active transport involving energy some passive absorption

Accessory Organs:

4/7/2013 6 Accessory Organs There are two accessory organs to the digestive system Pancreas Liver

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