BIOL370 Lecture Notes - Lecture 9: Specific Dynamic Action, Glut5, Gastrovascular Cavity
24 Dec 2012
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Document Summary
Digestion is a highly complicated process: associated subordinate/symbiotic organisms, multiple interacting cell types & molecules. Different nutrients undergo different digestive pathways: proteins vs. carbohydrates vs. lipids. Digestive systems increase in size & specialization as they increase in complexity: structure-function relationships are present in almost all areas. Digestion: assimilation: process of nutrient acquisition, digestion, & absorption (gi tract - external, egestion: excretion of undigested food. Energy content: protein & carbohydrates = 4 kcal/gm; fat = 9 kcal/gm, some food is indigestible (e. g. fibre), energy is lost in feces or urine, some energy is spend in digesting the food. Specific dynamic action (sda): increase in metabolic rate during digestion (thermal energy) Symbiotic organisms & digestion (3: enterosymbionts: lives within the lumen of gi tract (e. g. cecum) Birds eats wax in beehives, bacteria within the bird gut break down the wax into shorter. C units that can be absorbed by the bird: exosymbionts: cultivated outside of the body.
