The Digestive System consists of the Alimentary Canal and various other organs whose primary function is to support the Digestive System.
The Alimentary Canal, is a long tube about 10 meters long which starts at the mouth and ends at the anus. This tube consists of multiple sections which each have their own specific functions to perform in the process of digestion. The sections of the Alimentary Canal in the order in which they process food are:
Mouth: the teeth in the mouth help to physically crush and break-up the food into smaller pieces to increase their surface area so that it can be processed in later stages of digestion. Also, saliva helps to soften food to make it easier to process, and also begins chemically breaking down the food so that it can be processed in later stages of digestion. The tongue helps to mix the crushed food with saliva.
Throat: the act of swallowing pushes the food from the mouth to the Esophagus.
Esophagus (also called Oesophagus): The Esophagus is a 10-inch long tube that connects the throat and Stomach. Muscles in the wall of the Esophagus contract in synchronized waves, called peristalsis, where the muscles behind the food contract, squeezing it forward, while muscles ahead of it relax, forcing it to advance towards the Stomach, a process.
Stomach: Powerful Stomach muscles churn and mix the food, while glands in the walls of the Stomach secrets acids and enzymes which chemically break down the food into very small particles and molecules, so that these can be processed in later stages of digestion.
Small Intestine: In the upper section of the Small Intestine, called the Duodenum, bile and pancreatic digestive juices mix with other juices secreted by the wall of the Small Intestine to continue the break down of food. The food then enters the Ileum, the longest section of the Small Intestine, where nutrients are absorbed through the wall of the Small Intestine and transferred around the body via the blood stream (Circulatory System), to nourish and provide energy to all of the cells and organs of the body, allowing them to grow, repair, and perform the functions necessary to maintain life and fight disease, as well as allowing us to be able to move, think, breath, see, hear, and so on.
Large Intestine (also called the Colon and Bowel): In the Large Intestine, nearly all of the water is absorbed, leaving a usually soft but formed substance called stool. Muscles in the wall of your Colon separate the waste into small segments that are pushed into your lower Colon and rectum.
Rectum: The Rectum provides a temporary storage place for the waste products of digestion. When the rectal walls are stretched, they signal the need for a bowel movement.
Anus: The powerful sphincter muscles in the Anus prevent the release of waste products from the Rectum until the person is ready to expel them from the body.
Various other organs in the body perform functions that are important to digestion or support digestion, and these include:
Gallbladder: stores and concentrates bile, and then adds it to food as it enters the Duodenum, the upper portion of the Small Intestine.
Liver: performs 100’s of useful functions, including nutrient storage, filtering and processing of chemicals contained in food, detoxifying harmful substances, purifying your blood, manufacturing vital nutrients, and bile production, a solution that helps digest fats and eliminate waste products from the body. Bile, a fluid secreted by the Liver, is essential for the proper digestion of fats and helping the body rid itself of worn-out red blood cells, cholesterol, and potentially toxic chemicals and metals. The Liver is responsible detoxifying harmful substances that a person may eat, drink, inhale, rub on their skin, or which otherwise enter the body.
Pancreas: plays important roles in both digestion and metabolism, and is a large, long, flat gland which is located behind the lower part of the Stomach and in between the Duodenum (the upper part of the Small Intestine) and the Spleen. Among other functions, the Pancreas produces digestive enzymes that help break down proteins, carbohydrates, and fats.
As a result of the Digestive System, the body is able to:
- Extract nutrients from food and drink, and use these for growth, repair, and the maintenance of life.
- Process and discard waste products from the body as faeces (also called stools).
Each organ of the Digestive System and each section of the Alimentary Canal has specific and important roles to play in the digestion of the material we ingest.
The healthy transit time of food through a healthy human adult body (from mouth to anus) is less than 24 hours.
However, recent research has shown that this time has been greatly extended beyond what is considered safe or healthy, particularly in the Western World, where the average for men is approximately 60 hours, and 70 hours for women. This is because of diet and lifestyle factors.
As a result, food is remaining in the body longer (almost 3 times as long as it should be), and taking longer to process, and this can elevate the risk of a range of health complications, such as constipation, digestive problems, bowel problems, and even bowel cancer.