The human digestive system

To live, grow and maintain our bodies, we need to consume food.

But what about the foods we eat? How do nutrients in food reach our body cells?

To stay alive, continually renew cells, develop our bodies and maintain vital activities, we need food, as they provide energy to our body.

Structure of the digestive system

After a meal, the nutrients in food should reach the cells. However, most of them do not reach them directly. They need to be transformed to nourish our body. This is because cells can only absorb simple nutrients and this process of "simplification" gets its name from digestion.

The digestive enzymes

Our body produces various types of digestive enzymes. Each type of enzyme is able to digest only a certain species of molecule present in food. Thus, the amylases action the enzymes that act only on starch; at proteases act on proteins; at lipases about lipids, and so on.

There are substances that no human enzyme can digest. One is the cellulose, which participates in the formation of the plant cell wall. Because cellulose is too large a molecule to be absorbed and undigested, it is eliminated with faeces.

Digestive tract

The digestive tract consists of the following organs: mouth, pharynx, esophagus, stomach, small intestine and large intestine.


The mouth is the first structure of the digestive system. Try opening your mouth. The opening that forms between the upper and lower lip is called mouth slit. It serves as communication of the digestive tract with the external environment; That's where the food comes in. The "roof of the mouth" is also called palatine veil or hard palate. Towards the bottom is the "bell" or palatal uvula.

The upper dental arch and the lower dental arch are the arch-shaped structures in which the teeth are arranged and fixed.

The floor of the mouth is occupied by language. It contributes to the mixing of food with saliva, holds food close to the teeth, pushes food into the pharynx, cleans teeth and is the important organ of speech. The language also presents the lingual papillae, structures responsible for tasting.

Attached to the mouth are three pairs of salivary glands, which are saliva producing bodies.

THE Spittle contains an amylase-like enzyme called ptaline, which acts on starch and transforms it into maltose, a sugar variety formed by the union of two glucose molecules.