Our digestive system might seem a little odd at first, but we have nothing on cows. This system basically has more of everything from stomach compartments to bacteria. Things are weird from the start -- a cow chews and re-chews, up to 60,000 times a day. Once food has slipped down the esophagus, it lands in the first of four stomach compartments, the reticulum. This section allows the cow to regurgitate its food for even more chewing. Next, the well-chewed food moves to the rumen. Bacteria and protozoa aid the digestive process -- in this compartment alone there are half a million bacteria and 50 billion protozoa.
Next, the food slides right into the third compartment, the omasum. Here any of the volatile fatty acids that weren't absorbed in the second compartment get absorbed along with liquids like water and potassium. All this absorbing dries out the remaining food products, which are now ready for the last compartment, the abomasums. This is often called the "true" stomach because it works much like your stomach. The rest of the digestive system is no surprise -- small intestines, large intestines and rectum. All of these stomach compartments give cows a hugely productive digestive system. In 10 months, a cow can ingest enough protein for you to thrive for 10 years, enough energy for five years, and enough calcium for 30 years [source: General Anatomy of the Ruminant Digestive System].
Digestive Accessories: Organs and Glands
The stomach and intestines get a lot of help from other organs, glands, hormones and a few nerves. Let's look at what these digestive accessories do and how they've made themselves essential to the process.Organs
The main organ involved in digestion is the largest in the body, the liver, which accounts for about 2.5 percent of your overall body weight [source: Gastro.net]. The liver has a big impact on your bodily functions. In terms of digestion, it is involved in breaking up, digesting and absorbing fats. This is all thanks to bile, a brownish-yellowish fluid that's made in the liver and excreted through the bile ducts and into the small intestine.
The liver's extra bile is stored in the gallbladder. When food starts heading to the intestines, they signal the gallbladder to give up the bile. If the gallbladder has to be removed for one reason or another, the liver just stores the extra bile in newly expanded bile ducts.
The pancreas may be smaller than the liver, but it's an efficient factory. It produces pancreatic juices, which are made up of enzymes that help in digestion. An enzyme is a protein that can cause chemical changes in organic substances like food. The enzymes in the pancreas cause chemical changes that, with the help of bile, break down proteins, fats and carbohydrates.Glands
Essential glands are all over the digestive system, from the mouth to the intestines. In the mouth, salivary glands are there to start the process. Saliva moistens your food and uses an enzyme to begin breaking down starch into smaller molecules.
The stomach glands excrete juices that are a little stronger. When the food arrives, glands in the stomach lining squirt out acids that break down food. They also produce an enzyme specifically designed to break down proteins, like in meat. This breakdown continues when the food encounters even more glands in the intestinal walls. These are in charge of excreting enzymes that work with bile and the pancreatic juices to keep breaking down food and absorbing its nutrients.