What is the digestive system made of?

The digestive system consists of digestive tract and digestive glands.

1, the digestive tract is a long muscular tube, starting from the oral cavity, continuing to the pharynx, esophagus, stomach, small intestine and large intestine, and finally reaching the anal canal, including the oral cavity, pharynx, esophagus, stomach, small intestine (duodenum, jejunum and ileum), large intestine (cecum, appendix, colon and rectum) and anal canal. There are two kinds of digestive glands: small digestive glands and large digestive glands.

Small digestive glands are scattered in the digestive tract wall, while large digestive glands have three pairs of salivary glands (parotid gland, submandibular gland and sublingual gland), liver and pancreas, all of which discharge secretions into the digestive tract through catheters.

2. Digestive gland refers to the gland that secretes digestive juice in animals. There is a connective tissue capsule outside the gland, which goes deep into the parenchyma of the gland and divides the gland into several leaves and lobules. Glands consist of secretory part and excretory part. Such as large salivary glands, pancreas and liver are independent organs. The secretions and enzymes of various digestive glands are different, and food can be broken down into various small molecules through synergistic action, which is beneficial to the body's absorption and utilization.

Extended data:

The basic physiological function of the digestive system is to ingest, transport, digest food, absorb nutrients and excrete waste. The completion of these physiology is beneficial to the coordinated physiological activities of the whole gastrointestinal tract.

The digestion and absorption of food provide the substance and energy needed by the body. In addition to vitamins, water and inorganic salts, nutrients in food can be directly absorbed and utilized, while protein, fat and sugar can not be directly absorbed and utilized by human body, but can only be decomposed into small molecular substances with simple structure in digestive tube for absorption and utilization. The process that food is broken down into small molecules with simple structure and can be absorbed in the digestive tract is called digestion.

The pharynx is a common channel for digestion and breathing. It is wide at the top and narrow at the bottom, slightly flat at the front and back, located behind the nose, mouth and throat and in front of the cervical vertebra, and is about12 ~14 cm long; Its upper end is attached to the back of sphenoid bone and occipital base, and it is dome-shaped, called pharyngeal vault, and its lower end is connected with esophagus at the sixth cervical plane.

The posterior pharyngeal wall is intact, with loose connective tissue separated from the anterior vertebral fascia; The front wall is not complete, and it opens in the nasal cavity, oral cavity and throat cavity, thus dividing the pharynx into three parts: nose, mouth and throat.