What is Digestion?
Living things, especially the mammals need to eat in order to survive. To get the nutrients from the food, a process called digestion must take place. Digestion is both a mechanical and chemical process of breaking down foods. The body needs to break down foods into smaller components so that the body can absorb it. Digestion is a good example of catabolism, which is a metabolic process of breaking down large molecules into smaller ones.
As mentioned earlier, digestion is important for living things (especially man and animals) to survive. So how does digestion work? Humans have the so-called digestive system, which is responsible for the whole the digestion process. The digestive system is composed of several organs for the mechanical and chemical breakdown of food. Digestion is a systematic process and it takes entirely about 24 to 72 hours to finish.
Digestion begins in the mouth or oral cavity as the food enters. Chewing is the very basic mechanical process of breaking down food for digestion. As the food is chewed, saliva plays an important role in softening the food. Saliva contains enzyme that prepares chewed food for further breakdown.
Chewed food from the oral cavity will then pass through a long tube known as the esophagus. It is like a tunnel, which is composed of ring shaped muscles used for successfully swallowing food. The esophagus is specifically designed to bring the partially broken down food to the stomach. This makes swallowing food possible even if you are in an upside down position. However, please do not try swallowing food from this position.
The food passing through the esophagus will be grinded further in the stomach. The stomach is a pouch like organ that looks like the letter J. This organ is the most important part of the digestive system in mammals. It is in the stomach where breaking down of food particles occurs. The liver and pancreas produce digestive enzymes that aid in chemical breakdown of food molecules. The chemical process breaks down food and prepare for absorption.
The digested food from the stomach will then be ready for absorption. The next part that will take the digested food is the small intestine. It is a very long organ and may measure from seven to 8 meters in length. Chemical process also takes place in the small intestine particularly in the duodenum. After passing through the duodenum, the food will pass through the jejunum where nutrient absorption takes place. The ileum is the last part of the small intestine. This part absorbs the vitamins and nutrients missed by the ileum.
After the small intestine, the remaining food will be passed to the large intestine. It is in the large intestine where digested food is fermented. The large intestine has also three parts: cecum, colon and rectum. The cecum connects the small and large intestines. The second part is the colon, which eliminates water and salts from the digested food. The last part is the rectum, which is connected to the anus. The rectum controls the excretion of the stool. The digested and fermented food will be eliminated by the body through bowel movement.