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# Digestive System Structure ## 2.2 Structure of the Digestive System The human digestive system is a complex combination of a tube (the digestive tract) and accessory glands. The digestive tract starts at the mouth and ends at the anus. Along with the tract, various glands secrete digestive enzy...

# Digestive System Structure ## 2.2 Structure of the Digestive System The human digestive system is a complex combination of a tube (the digestive tract) and accessory glands. The digestive tract starts at the mouth and ends at the anus. Along with the tract, various glands secrete digestive enzymes in specific zones. Accessory glands secrete substances to aid in breaking down food into usable nutrients. ### Mouth and Pharynx * **Mouth:** The mouth is the beginning of the digestive tract. It is bordered by the palate, the floor of the mouth, and the cheeks. The back of the mouth leads to the pharynx. * **Teeth:** Teeth are located in sockets (alveoli) within the mandible and maxilla. * **Tongue:** The tongue is a muscular organ that helps form food into a bolus during chewing. It also plays a role in taste perception and speech. * **Salivary Glands:** These glands (parotid, submandibular, and sublingual) produce saliva which contains enzymes to begin the process of breaking down food. * **Lips:** Two muscular folds that protect the opening of the mouth. They aid in speech as well. * **Pharynx:** The pharynx connects the nasal cavity to the mouth and esophagus, and the respiratory system. Its approximately 12-13 cm long, and serves as a conduit for the food bolus from the mouth to the esophagus. The epiglottis is found in the pharynx, and it helps prevent food from entering the trachea (windpipe) during swallowing. The image also depicts the various salivary glands (parotid, submandibular, and sublingual) and their locations in the mouth region. There is a labeled diagram showing the different parts of the mouth and pharynx, as well as the associated salivary glands.