Digestive System Development

Digestive System Development The digestive system consists of two parts: the digestive tract and the digestive gland.

The digestive tract is a long, muscular duct from the mouth that continues the pharynx, esophagus, stomach, small intestine, large intestine, and anus. The organs that pass through include the mouth, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, ileum) and the large intestine (cecum, colon, rectum). The digestive gland has two small digestive glands and one large digestive gland. The small digestive glands are scattered in the wall of each part of the digestive tract. The large digestive glands have three pairs of salivary glands (the parotid gland, submandibular gland, sublingual gland), liver and pancreas, all of which are discharged into the digestive tract by means of a catheter.

The basic physiological functions of the digestive system are ingestion, transport, digestion of food and absorption of nutrients, and excretion of waste. These physiological processes are beneficial to the coordinated physiological activities of the entire gastrointestinal tract. The digestion and absorption of food, the substances, and energy required by the body, the nutrients in the food, except vitamins, water, and inorganic salts, can be directly absorbed and utilized, and proteins, fats, and sugars cannot be directly absorbed and utilized by the body. It needs to be decomposed into small molecular substances with a simple structure in the digestive tract to be absorbed and utilized. The process by which food is broken down into small molecules that are simple in structure and can be absorbed in the digestive tract is called digestion. The process by which small molecules pass through the gastrointestinal mucosal epithelial cells into the blood and lymph is absorbed. For the portion of the residue that is not absorbed, the digestive tract is excreted in the form of feces through the large intestine.