Explore The Digestive System

Starting from the mouth to the anus, the Digestive system helps to break down the food we consume into smaller pieces so that the body can absorb the nutrients the body needs. The digestive system consists of the mouth, esophagus, stomach, liver, gall bladder, pancreas, small intestine, large intestine, rectum, and anus.

The Mouth:

Digestion first takes place in the mouth. The mouth is the first organ In the  mouth, food is broken down into smaller pieces by the teeth and saliva. Saliva is produce by the salivary glands. Saliva also breaks down starch into mono or disaccharide because saliva contains amylase enzymes that breakdown starch.

The Esophagus:

After food is is broken down into smaller pieces, the food is transported by the esophagus, which is a long tube that goes from the mouth to the stomach. Food is move by the wave-like muscle movement also known as peristalsis. 

The Liver:

Bile is produce in the liver, which helps to break down fats in the small intestine and carries away waste. It also helps with the production of cholesterol and special proteins to carry fat through the body.

The Pancreas:

When food enters the stomach, enzymes such as lipase, which break down fats, help break down other macromolecules such as carbohydrates, proteins and acids. After a rise in blood sugar levels, the pancreas secretes insulin, which regulates the amount of glucose in the body.

The Gall Bladder:

Bile is stored and secretes in the Gall Bladder. It also keeps excess bile when there is pressure in the bile ducts.

The Stomach:

Hydrochloric acid produced by parietal cells  in the stomach helps to kill bacteria and denature proteins. It also helps to store food. Pepsin enzymes starts proteins. Peristalsis helps other enzymes to be release. The gastric pits release gastric acid, protective mucus, and enzymes. Muscular spinsters helps to control the entry of food and the exit of chyme. The hormone PPY, is secreted in the small intestine after meals, that acts as an appetite suppressant.

The Small Intestine:

Divided into three parts the duodenum, jejunum, and the ileum, the small intestine completes the digestion of food molecules. Chyme enters the duodenum. Bile is emptied in the duodenum, which neutralizes the acid from the stomach and emulsifies fats. Pancreas enzymes such as amylase and trypsin released in the jejunum. In the last stage of of the stage of the small intestine ( the ileum) digestion food food takes place. Villi; finger- like projections, help with absorption by increasing the surface area.

The Large Intestine:

Once absorption has taken place in the ileum, the undigested food goes to the large intestine. The large intestine reclaims as much water as possible to the blood, before allowing egestion of the solid feces. By being long and folded,  the large intestine maximizes its surface area for better water absorption. Bacteria breaks down undigested molecules. The large intestine secretes mucus to lubricate the passage of the feces and peristalsis keeps the feces moving.

The Rectum:

Feces is temporary stored in the rectum until it is eliminated through the anus.The rectum is made up of muscular walls that expand to hold feces. When expanded, nerves in the rectum send signals to the brain that lets you know to have a bowel movement.

The Anus:

The last part of the digestive track is the anus. It keeps us continent when we are asleep or unaware of the presence of feces. We rely on the external sphincter to keep feces in until we can it is released.

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Links:

http://www.webmd.com/digestive-disorders/digestive-system

http://science.nationalgeographic.com/science/health-and-human-body/human-body/digestive-system-article/