Gastrointestinal system anatomy and physiology

The gastrointestinal tract consists of a long tube, where food travels through, which runs from the mouth to the anus, as well as a number of accessory organs that sprout off the sides of that tube.

The gastrointestinal tract is made up of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and finally the anal canal.

The accessory organs include the teeth, tongue, salivary glands, the liver, gallbladder, and the pancreas.

The main job of the gastrointestinal system is ingestion - taking in food, digestion - breaking it down into nutrients, absorption - pulling these nutrients into the bloodstream, and finally, excretion - getting rid of waste.

All right, so let’s say we eat a slice of pizza. The pizza goes in our oral cavity where we use our teeth to masticate, or chew the food up into small fragments.

These fragments get tasted and rolled around by the tongue, which is basically a huge muscle that lines the floor of the mouth.

The roof of the mouth, which separates it from the nasal cavity, is made up by the anterior hard palate, which provides a hard surface for the tongue to mash food against and the posterior soft palate, which moves together, along with the pendulum- like uvula to form a flap or valve that helps makes sure food flows down instead of going up into the nose.

At the same time, the three sets of salivary glands - the sublingual, below the tongue, the submandibular, below the mandible, and the parotid gland, which is near the ear all secrete saliva to lubricate the food.

The saliva helps to make the food compact down into a soft, warm ball, called a “bolus”.

Saliva also contains salivary amylase, an enzyme that breaks long carbohydrates down into smaller sugars.