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The Difference Between the Human Digestive System & the Digestive...

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The Difference Between the Human Digestive System & the Digestive System of a Cow

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  • May 2013
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“The Difference between the Human Digestive System & the Digestive System of a Cow” Digestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be absorbed, for instance, into a blood stream. Digestion is a form of catabolism; a break-down of macro food molecules to smaller ones. Digestion begins in the mouth, for a cow the teeth structure is very different from humans. Instead of having two rows of sharp incisors, cows have a single, bottom row of incisors and a dental pad where humans have a top row of incisors. Because much of what cows consume is tough plant fibre, they cannot simply break it apart by chewing it as humans would. They must break it down by repeatedly grinding it against the dental pad, much like a pestle grinds down tough material against a mortar. The cow's oesophagus, which transports food from the mouth to the stomach, also functions differently from human. Its design is for two-way transport; cows repeatedly regurgitate and re-chew their food to further break it down and allow for more efficient digestion in the stomach. In contrast, humans only chew their food once. For humans, regurgitating food is a sign of an upset stomach. The primary compartments of a cow's stomach are the rumen and the reticulum. The rumen is the larger of these and serves as the primary storage chamber. It accommodates 25 gallons of food with far more than the single gallon a human stomach can accommodate. Food that passes into the rumen gets digested not by enzymes or acid as in the human stomach, but by the millions of microbes that live there and break down food through a process called rumen fermentation. Unlike the human stomach, which is relatively immobile, the rumen contracts about two times each minute, mixing its contents and ensuring that all food encounters the digestive microbes. Rumen fermentation is the process by which the microbes living in the cow's rumen break down the cellulose, or fibre, in...