Physiology 3120 Lecture Notes - Lecture 6: Lingual Lipase, Uniporter, Symporter
7 Apr 2017
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Complex carbs highly branched monomers (oligosaccharides) i. e. starch, glycogen. Salivary amylase acts in the mouth bc it"s in optimal ph for activation. Oligosaccharides & disaccharides cannot be absorbed must be digested to monosaccharides. Amylopectin: branched glucose polymers: cleaved by alpha-dextrinase, alpha-limit dextrins: shorter branched glucose polymers, later broken down to monosaccharides. Glut 5 uniporter: fructose uniporter on luminal and basolateral membrane (gradient independent only fructose) Glut 2 uniporter: monosaccharide (glucose, lactose, fructose) uniporter. Smaller peptides allow amino/carboxypeptidase to better chop it up to single aa. Different endopeptidase recognize different aa sequences for cleavage. In general: luminal symporter, basolateral exchanger. H+ enters and leaks out of cell mechanism to keep transport electroneutral & to maintain function of cotransporter. Di/tri-peptides are mostly digested by peptidase in the cell to form single aa. Transcytosis: small whole proteins carried across the cell: babies are capable of doing this, carries antibodies from mother across for absorption, thought to stop ~4-6 months of age.
