NUTR 3210 Lecture Notes - Lecture 3: Foregut, Pepsin, Proventriculus
4 Feb 2017
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Gi tract = digestive tract (does not equal digestive system) Digestive system = gi tract + associated organs that contribute to digestion (liver etc) General terminology for dietary carbs (cho) and digestion. Digestibility: does the host organism have the molecular machinery to digest all cho: digestible cho versus non-digestible cho (fiber) Solubility: is cho soluble in the aqueous environment of the digestive tract: yes= soluble; no= insoluble. Ferment-ability: do gut bacteria have the molecular machinery to break down cho: yes=fermentable; no = non-fermentable. Key features: mono-gastric, non-functional caecum, suited for nutrient dense, low fiber diet. The human digestive tract is ~ 16 ft. Two enzymes release: a-amylase (carbs) and lingual lipase (dietary fats) Gastric glands secrete gastric juice: h2o, electrolytes, hcl, enzymes. Ph of stomach is acidic ~ 2. Enzymes from the mouth are deactivated by this point. Main site for nutrient digestion and absorption. Digestion of food pancreatic juice, bile acids. Intestinal motility controlled by longitudinal and circular muscles.
