Digestion - Digestion

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LR/CC/FNB UNIT 2 :Nutrition Topic 7 : Digestion
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LR/CC/FNB What happens when we eat food L L Absorption, uptake into body L Distribution & allocation
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LR/CC/FNB 1: The Mouth L Mastication, L physical breakdown of food structure L Enables swallowing of large items L Increase in surface area for digestion L Saliva L L Salivary amylase, can breakdown starch to maltose, but usually not enough time and inactivated at pH 4.0. Absent in most animals. L Lingual lipase
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LR/CC/FNB
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LR/CC/FNB 2: The Stomach L Large sack with a muscular wall, L completes mechanical breakdown of food L useful as a temporary storage L Heat emulsifies fats L Acid secretion, gastric juice L HCl at 2L per day, from parietal cells of gastric pits in wall. L pH 1.0 , kills micro-organisms L Denatures proteins
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LR/CC/FNB 3: Stomach enzymes L Pepsin L Is an endopeptidase, breaks down proteins L L Produced as inactive pepsinogen which is cleaved by acid to form the active pepsin L Rennin L Acts to coagulate casein in milk L Which can then be degraded by pepsin L Only present in children L Gastric Lipase L Digestion of 30% of dietary fat
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LR/CC/FNB
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LR/CC/FNB 4: Duodenum L Bile secretion L Produced by liver, stored in the gall-bladder L Slightly alkaline, helps neutralise stomach acid, pH 7.5 – 8 L Bile salts, emulsify fats by lowering surface tension. L Excretion, especially of cholesterol, can lead to formation of gallstones.
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LR/CC/FNB
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LR/CC/FNB Sodium taurocholate
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LR/CC/FNB 5: Duodenum L Pancreatic secretion, lots of enzymes L Proteases, degrade proteins L 3 endopeptidases, L 1 exopeptidase, Carboxypeptidase L Amylase, degrades starch L Lipase, degrades fat L L also alkaline, bicarbonate secretion
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LR/CC/FNB 6: Small Intestine, or Ileum L Not so small ~6m long! L
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This note was uploaded on 07/04/2011 for the course BIO microbiolo taught by Professor Point during the Spring '09 term at HKU.

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Digestion - Digestion

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