Hi,
I have an assignment with the following question:
"Outline the process of carbohydrate absorption and the possible fates of food energy in the body."
I've outline the process of carbohydrate absorption, but I am looking for some help with the possible fates of food energy. I think it may be something along the lines of "The various fates of food energy in the body are energy output (internal and external work) or energy storage." Should I maybe discuss what specific nutrients do for the body?
Here's what my answer is so far:
Carbohydrate absorption is done in the epithelial lining of the small intestine. It is absorbed in uncontrollable amounts (unlike calcium and iron). It’s absorption process is active ( thus requiring energy) and through carrier-mediated transport. Sodium is also involved in this process, acting as a cotransport mechanism for carbohydrates absportion into the blood. Carohydrates are first broken into their smaller forms - first disaccharides (maltose, sucrose, lactose), then, as these forms pass along the brush border, they are reduced to monosoaccharides (glucose, galactose, fructose) - which are absorbable forms. Glucose and galactose are absorbed by cotransport mechanisms (secondary active transport) that also carry sodium into the cell. This is secondary active trasnport because the mechanism depends on the sodium concentration gradient created by the basolateral sodium-potassium pumps. After entering the cell, glucose and galactose can diffuse down their concentration gradients and into the blood. Fructose, on the other hand, does this entirely through diffusion and thus it is a passive mechanism.
Energy is input to the body through food energy. Food energy is used for metabolic processes in the body. The various fates of food energy in the body are energy output (internal and external work) or energy storage.Depending on the type of nutrient entering the body, it will have a different function.When food enters the body, it is known as energy input. In food, there is chemical energy in bonds that must be broken down through digestion so that it may be used for energy (stored or immediate). Immediate energy output can consist of internal (non-mechanical work to maintain the body systems) or external work (mechanical work, ie: exerting force on an object). If unable to be used for work, it could also be converted to heat (thermal energy). About 50% of the energy from ingested food is converted, and lost, to heat. Another 25% is lost when energy is used for work.
Thanks for any suggestions!
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