Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: Erica on 23/10/2010 12:30:04

Title: What changes food so your body can make use of it?
Post by: Erica on 23/10/2010 12:30:04

Erica asked the Naked Scientists:
   
What changes food so your body can make use of it?

What do you think?

Title: What changes food so your body can make use of it?
Post by: SteveFish on 23/10/2010 19:32:45

Cooking helps. Mastication (chewing) breaks up the food and saliva adds some digestive enzymes and lubrication for swallowing. The stomach has muscular folds (rugae) that mix the food with hydrochloric acid and acid hydrolases (more digestive enzymes) to break down starches into sugars, proteins into peptides and amino acids, and fats into absorbable constituents. The finished product of the stomach, called chyme, is expelled into the small intestine.

The small intestine is where digestion continues via more enzymes and specialized cells (enterocytes) that bring products of digestion into the body by endocytosis, molecule specific membrane transport, and direct diffusion for some components of fats. For one example, there are specific membrane protein transport machines that are specialized for "grabbing" specific single sugar molecules and transporting them across the cell membrane that faces the GI tract to the inside of enterocytes, and others that transport them out of the cell into the body.

All of these mechanisms are specific for needed digestive components for the energy, maintenance, and/or growth requirements of the body. This is a sorting process that maximizes import of needed molecules while minimizing substances and organisms that are not needed or are harmful.