How the Digestive System Works

Knowing how the digestive system functions helps to understand the different phases of processing and delivering nutrients to different parts of the body.

The Digestive System

By definition, digestion is the process of breaking down what we eat into components that can be absorbed by our bodies. These components are easily assimilated into the blood stream and distributed to different areas in the body.

Phases of Digestion

1. Cephalic Phase: Preparation for digestion begins with the cephalic phase. Saliva is produced in our mouth while digestive enzymes are produced in the stomach and small intestines. Saliva softens the food we eat to make it easier for the stomach to break it down easily.
2. Mechanical Digestion: This phase of digestion physically breaks down the food into smaller pieces. Mechanical digestion is basically chewing the food.
3. Chemical Digestion: Chemical digestion also begins with the mouth, but differs in process with its mechanical counterpart. This process starts with the saliva softening the food we eat then passing it through the esophagus to the stomach. Here, digestive enzymes break it down into smaller components for easy absorption and assimilation into the blood stream
4. Absorption Phase: This phase defines the movement and distribution of nutrients from the stomach (digestive system) to the lymphatic and circulatory capillaries.
5. Egestion Phase: This phase defines the removal of undigested material from the stomach through the small intestines, large intestines, and out through the anus -- or simply termed as defecation.

Digestive disorders might occur at almost any phase in this process.

Parts of the Digestive System

Now that we have a thorough understanding of how digestion starts and ends in the digestive system, the next thing is the digestive system itself. This includes basic components that make up the phases of digestion. These are:

1. Oral Cavity: The oral cavity is where food is chewed, breaking it down into smaller components for easy digestion in the stomach. The oral cavity is in charge of mechanical digestion and begins the chemical digestion before passing it on to other parts of the digestive system. Saliva is produced through the tongue and mixed with the food. This softens it for chewing, easy swallowing and digestion in the stomach.
2. Esophagus: This part of the digestive system is composed of smooth muscles that serve as a pathway for the processed food from the mouth to the stomach.
3. Stomach: The stomach acts like an elastic bag that holds the initially digested food and finishes the digestive process. Digestive enzymes and gastric juices flow into the stomach aiding in digestion. The acid is not used as a means of breaking down food, it aids digestive enzymes in breaking down food components into a form that can easily be absorbed by the body.
4. Small Intestine: This is where most of the digestion and absorption of nutrients occurs. Other liquids mix with the food in order to proceed with the rest of the digestive process. These liquids are bile, which is from the gall bladder and helps break down fatty components to be absorbed into the body, pancreatic Juice, which is produced by the pancreas that also breaks down digested components, and intestinal enzymes, such as maltase, sucrose, and lactase to process sugar.
5. Large Intestines: The large intestines absorb excess liquid from digested components and stores feces before it is egested from the body through the anus (defecation). Waste products, fiber, and other materials that cannot be digested by the system are stored in this section as concentrated feces.