NUSCTX 103 Lecture Notes - Lecture 4: Lactase Persistence, Mass Diffusivity, Lactase
3 Dec 2020
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Lecture #4: sucrase and lactase deficiency, results in indigestion since intact sucrose and lactate molecules cannot be absorbed, thus, they are available in the colon for microbial fermentation, resulting is production of gases including h2, co2, ch4. Increase rate and/or efficiency of cho absorption, cooking and small particle size. Indigestible carbohydrates: no digestive capacity for, alpha galactosidic bonds, glucose or fructose joined by beta glycosidic bonds, these carbs remain intact, transport to the apical membrane surface. Unstirred water layer (uwl: water soluble constituents, diffusion, lipid soluble constituents, unstirred water layer represents a major barrier, must be packaged into micelles, rate of transport determined by, concentration gradient, diffusion coefficient for the substance. Transcellular transport through the membrane: permeable to small non-polar molecules, highly impermeable to charged molecules, no matter the size. Crossing the apical membrane: plasma membrane is a substantial barrier. Passive vs active transport: passive solely employs the energy from an electrochemical gradient, active movement against concentration gradient, requires energy.
