17. Digestive System

The digestive system, also known as the digestive system, is one of the most important systems in the human body. It is responsible for food digestion, which is the process of breaking food down into nutrients that can be used by the body for energy, growth, and cell repair. The digestive system is made up of several organs, including the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus.

Digestion begins in the mouth, where food is chewed and mixed with saliva. Saliva contains enzymes that begin to break food down into smaller molecules. After chewing, food is swallowed and passes through the esophagus, a muscular tube that connects the mouth to the stomach.

In the stomach, food is mixed with gastric acid and other substances to form a mixture called chyme. Stomach acid helps break down food even more, especially protein. The stomach also produces an enzyme called pepsin, which helps with protein digestion.

From the stomach, chyme passes into the small intestine. The small intestine is where most of the digestion and absorption of nutrients takes place. It is divided into three parts: the duodenum, the jejunum and the ileum. In the duodenum, chyme is mixed with bile, a substance produced by the liver that helps digest fats, and pancreatic juices, which contain enzymes that help break down carbohydrates, proteins, and fats.

After passing through the duodenum, the chyme passes into the jejunum and ileum, where nutrients are absorbed into the bloodstream. The walls of the small intestine are lined with villi, small projections that increase the absorptive surface.

Undigested waste passes from the small intestine into the large intestine, also known as the colon. The colon absorbs the remaining water and mineral salts, turning the undigested material into stool. The stool is then stored in the rectum until it is eliminated through the anus.

In addition to the organs mentioned above, the digestive system also includes the liver and pancreas. The liver produces bile, which helps in the digestion of fats. It also plays an important role in detoxifying the body, processing and eliminating harmful substances. The pancreas, on the other hand, produces pancreatic juices that contain digestive enzymes. In addition, the pancreas also produces insulin, a hormone that helps regulate blood sugar levels.

In summary, the digestive system is essential for the health and well-being of the human body. It is responsible for breaking food down into nutrients that can be used by the body for energy, growth and cell repair. A complete understanding of the digestive system is fundamental to understanding human biology and is an important topic for studying exam biology.

Next page of the Free Ebook:

37Excretory System

3 minutes