digestion
Wednesday, May 12, 2010 @ 5:19 AM
CARBOHYDRATYES:
FATS(FATTY FOOD):
PROTEIN:
Why is there a need for digestion?
We simply learnt that digestion needs to occur so that the large insoluble food molecules can be broken down into smaller soluble molecules so that it is able to be absorbed into the bloodstream.
But there's more than just that. Let me elaborate more.
SIGNIFICANCE
Digestive enzymes are crucial for breaking down food, so it can be absorbed by the body. Once food is broken down into smaller molecules that can be absorbed into the bloodstream, the nutrients can be distributed to all the cells in the body and used to fuel all the cells' activities.
FUNCTION
Digestive enzymes are proteins that break specific molecular bonds. The bonds release smaller molecules from the larger food particles in the digestive system. Many different digestive enzymes work in sequence to turn food into small molecules that can enter the blood stream.
TYPES
There are enzymes specific for fats, proteins and carbohydrates. Starches are polysaccharides, made up of many sugar molecules linked together, and are digested by amylases. There are specific enzymes that break apart specific pairs of sugar molecules after amylase has broken starches into disaccharides.
LOCATION
Digestion starts in the mouth. As the teeth grind the food into smaller bits, amylase begins to break starches down into sugars, and lipases begin to break down fats. The stomach breaks food apart by a combination of acid, mixing and gastric enzymes (which work at the acid pH of the stomach). The pancreas makes amylase, lipase and a variety of enzymes to break apart proteins once the food is in the intestines. The intestines have a number of "brush border" enzymes, located on the intestine cells' membranes, that digest disaccharides, small peptides and nucleotides into smaller molecules.
BENEFITS
Once food is broken down into small molecules (single sugar molecules, amino acids, fatty acids and nucleic acid components) the nutrient molecules can enter the blood. Fatty acids cross intestinal cell membranes and enter the blood. Other nutrients bind specific proteins on the intestinal cell wall and are transported across the intestinal cells and released into the blood. The nutrients in the blood bind to receptors on cells in the body and are taken up by the cells to provide energy and building blocks for the molecules that the cells need to make to function properly.
