My topic question is "How do the digestive systems in other animals work?"
Firstly we have to analyse the meaning and why the need of digestion.
Why is there a need for digestion?
The food we eat consists of large bulky molecules that cannot pass through the walls of the intestines into the blood vessels. Digestion is necessary to break down food into smaller, soluble and diffusible molecules that can be absorbed into our body. Digestion may be physical or chemical.
Physical breakdown of food into smaller pieces without any chemical change to the molecules of the food is called physical digestion.
Chemical digestion is the breakdown of large food molecules into smaller molecules. It involves the action of enzymes, which are special types of proteins produced by the body. The enzymes speed up specific chemical reactions in the body.
Most of the work of digestion requires the presence of enzymes. Enzymes are common proteins, but they are unique in that they can latch on to a specific molecule, such as another protein, and cut that molecule into smaller fragments.
Elsewhere in the body enzymes may do the opposite, namely build large molecules from smaller ones. But in the intestines, enzymes generally break apart molecules so that they can be more easily transported (absorbed) across the cells of the intestines and into the bloodstream. Thus, a meal that contains protein, triglycerides, and complex sugars (dissacharides) is degraded into amino acids, fatty acids, and simple sugars, respectively.
These smaller molecules are then absorbed and transported through the blood to places where they are needed.
In the second part of my entry I will be talking about the human's digestive system.
Links/Resources:
http://en.wikipedia.org/wiki/Digestion
The Stuff of Life by Eric P. Widmaier
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