Page 19 - Human anatomy COMPLETELY DONE1

In the oral cavity, food is crushed and soaked in saliva, which includes enzymes that
promote the breakdown of complex carbohydrates to simpler ones. Also, the substance
lysozyme partially disinfects food.
Next, the food lump is swallowed and enters the esophagus, the wave-like
contractions of which push food into the stomach. There is a sphincter between the
esophagus and the stomach, which normally opens and closes quickly, preventing the
acidic contents of the stomach from getting back into the esophagus.
The contraction of the stomach walls actively mixes the food. His glands secrete
gastric juice, which includes a small amount of hydrochloric acid. It kills many bacteria
and activates a number of enzymes. The enzyme pepsin breaks down proteins. Also,
some fats are broken down in the stomach, in particular milk fat.
From the stomach, the food gruel in portions enters the first part of the small
intestine – the duodenum. The ducts of the gallbladder and pancreas come out here.
Here, all nutrients (proteins, fats and carbohydrates) are subjected to more intensive
chemical cleavage under the action of various enzymes.
The liver (figure 12) produces bile, which first enters the gallbladder, and from
there, as necessary, is released into the duodenum. Bile promotes the emulsification of
fats, that is, their splitting into the smallest drops. Bile also activates enzymes of
pancreatic juice.

Figure 12.

The glands of the mucous membrane of the small intestine secrete intestinal
juice. Under the action of its enzymes, the cleavage of proteins to amino acids, fats to

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