Diagram of the Digestive System

We run, we work, we think, we talk. How do you think we do all of that? Yes as far as thinking and reasoning is concerned, our mind does play a big role. However, biologically our body is an amalgamation of different human body systems, each of which has a specific role to play. There are seven major organ systems that make up the human body. They are the nervous system, respiratory system, circulatory system, musculoskeletal system, digestive system, excretory system and the reproductive system. In this article we concentrate on the digestive system. To aid our understanding of the function and the various organs that constitute it, this article carries a labeled diagram of the digestive system and an unlabeled one at the end of the article for the readers to identify and mark different organs of the digestive system.

Digestive System Function

Our body is like a complex machine. It needs fuel to run. This fuel is provided by the food that we eat. The nutrients-carbohydrates and fats provide us this energy. However, just as a machine suffers from wear and tear, the cells of our bodies also wear out. New cells are required to replace the old and dead cells. The raw material for this growth is provided by proteins. We are also susceptible to a number of diseases which our immune system generally fights. Vitamins and minerals are the nutrients that strengthen our immunity. However, these nutrients need to be broken into simpler forms, that can be absorbed by our cells. This is where function of the digestive system begins. There are a number of glands like liver and pancreas (to name a few), that secrete enzymes into the various organs of the digestive system, that speed up the process of digestion. These enzyme, that are more specifically known as digestive enzymes, that aid in the reactions that break the complex nutrients in simpler forms, that can be transported by blood and absorbed by the cells. Read more about how does the digestive system work and benefits of digestive enzymes.

Digestive System Organs and Their Functions

This table gives a consolidated information about the different digestive system organs and their functions. Following diagram of the digestive system that is provided in the article, will give one a better understanding of this organ system, as the food moves down from the mouth, through the esophagus to the stomach, small intestine and the large intestine, before it is excreted through the rectum and the anus.

Digestive System Organ	Secretions	Function
Mouth/Oral Cavity	Salivary Amylase secreted by the 3 salivary glands - parotid, submandibular and sublingual.	We chew food to break them down into smaller pieces. This provides greater surface area for the enzymes released by the salivary glands to break down carbohydrates in the food.
Oesophagus	None	The esophagus does not have any digestive role. It just helps the food to be pushed down from the mouth down to the next organ, that is the stomach. This it does by the process of peristalsis.
Stomach	Gastric acid, pepsin (enzyme) and other digestive enzymes	The muscles of the stomach churn the food and mixes it with gastric juice and enzymes released into the stomach. The gastric juice maintains the acidic pH, so that digestion in the stomach can take place. Pepsin breaks down proteins (into amino acids). The other enzymes, that is, gastric amylase and gastric lipase, further breakdown carbohydrates and fats respectively.
Small Intestine	Bile and pancreatic enzymes secreted by the pancreas, intestinal enzymes.	It is in the small intestine that digestion is completed and all the nutrients (present in their simplest form) are absorbed by blood through the walls of the small intestine. Bile secreted by the pancreas emulsifies fat, so that it can be absorbed. The pancreatic and intestinal enzymes complete the final stage of digestion of proteins, fats and carbohydrates.
Large Intestine/Colon	None	The large intestine is mainly involved with the absorption of water and electrolytes from the undigested substance, that reaches it from the small intestine. It also stores this undigested material till it is ready to be excreted from the body through the rectum and the anus.

Digestive System Facts

Here are some facts about the digestive system:

• We produce almost one quart of saliva every day.
• Saliva is 98% water and only 2% enzymes.
• Length of the digestive tract is about 30 feet.
• Liver and pancreas are not a part of the digestive tract but they help in digestion by secreting powerful enzymes.
• Food stays in the stomach for almost 2 to 3 hours.
• The small intestine is almost 20 feet long.
• Food takes almost 4 hours to travel through the small intestine.
• The large intestine measures up to 5 feet in length.
• We excrete solid waste material through the anus, when the sphincter muscles lining it, relax.

So, you can see how the various digestive system organs work in co-ordination with each other to break down the food we eat into simpler forms, that can be easily absorbed by the cells of our body. Proper functioning of the digestive system is very important for our digestive health.

After you have read the article and studied the labeled diagram of the digestive system given in the article, try to identify and mark the various digestive system organs in this ready-to-use human digestive system diagram - blank worksheet to label. All the best!