Digestive system of mammals: features of the structure

Mammals are animals that feed their young with milk. They are the most highly organized. The excretory, sexual, digestive, respiratory and circulatory system of mammals is most complex in comparison with representatives of other systematic units. But special attention should be given to the structure of the digestive system.

Nutrition and digestion

Nutrition is one of the main signs of living organisms. This process consists in the ingestion of substances into the body, in their transformation and in the removal of unprocessed food residues. In specialized organs digestion occurs - the cleavage of complex organic substances (proteins, lipids, carbohydrates) into simple ones that can be absorbed into the blood. Why do biopolymers break up into their constituent parts? The fact is that their molecules are very large, and they can not penetrate from the digestive channel into the bloodstream. The digestive system of mammals is no exception. It has a number of features that distinguish them from other chordates.

Structure of the digestive system of mammals

This system of organs consists of two parts: the canal and glands. In the first, the food is digested, nutrients are absorbed into the blood, and its unprocessed residues are released. The digestive canal includes the following sections: the oral cavity, the pharynx, the esophagus, the stomach, the small and large intestine, ending with the anal opening. Through it, the undigested residues are removed. Features of the structure of the digestive system of mammals are also in the presence of glands. These are special organs in which enzymes are found - biological catalysts that promote the process of biopolymer digestion.

Features of digestion in the oral cavity

The organs of the digestive system of mammals, or rather the canal, begin with the oral cavity. Cheeks and lips form a pre-orifice cavity. It is here that two types of food processing occur. Mechanical is carried out with the help of differentiated teeth and tongue, the chemical - enzymes of the salivary glands. Here they split only one kind of organic substances - complex carbohydrates of polysaccharides to simple, monosaccharides.

The differentiation of teeth depends on the type of food and the way it is extracted. The predators have the most developed incisors, the herbivores are characterized by molar teeth of flat form, whales do not have teeth at all.

Digestion in the stomach

The edible lump from the oral cavity through the esophagus advances into the stomach - the most extended part of the whole canal. His muscular walls begin to contract and the food is mixed. Here it is subjected to chemical treatment. The digestive, circulatory system of mammals is closely interrelated. Gastric juice breaks down proteins and lipids into monomers - constituent parts. Only in this form they fall into the blood.

Digestion in the intestine

The digestive system of mammals continues intestines: thin and thick. Partially digested in the stomach food in small portions enters its first department. Here there is a final splitting and absorption of substances into the blood and lymph. The first section of the small intestine is called the duodenum. It opens the ducts of the pancreas and liver. The large intestine is the end section of the digestive system. Here, most of the water is absorbed and feces are formed, reflexively removed from the rectum.

Digestive glands

The digestive system of mammals is characterized by the presence of glands. These are the organs in which enzymes are located. In the oral cavity there are three pairs of salivary glands. They emit a colorless mucus. The composition of saliva includes water, enzymes amylase and maltase and mucus mucin. Each of them performs its function. Water moistens food, lysozyme detoxifies microorganisms and heals wounds, amylase and maltase splits carbohydrates, mucin has an enveloping effect.

The composition of gastric juice includes hydrochloric acid, which retards putrefactive processes and stimulates motor activity. Additional substances are the enzymes pepsin and lipase, which, respectively, break down proteins and lipids. Hydrochloric acid is a reactive substance, it is capable of eroding the gastric mucosa. This action is protected by mucus (mucin).

The pancreas produces digestive juice, consisting of enzymes of trypsin, lipase and amylase. They finally break down all organic matter.

The role of the liver is also great. It constantly forms bile. Getting into the small intestine, it emulsifies fats. The essence of this process is the disintegration of these biopolymers into small droplets. In this form they are more quickly split and absorbed by the body. Activation of enzymes, increased motor activity of the intestine, stopping putrefactive processes - this is also a function of the liver.

What are enzymes?

And now more about the nature and mechanism of action of enzymes. As biological catalysts, they accelerate chemical reactions. The digestive tract of mammals is essentially just the site of action of the enzymes.

Features of nutrition of mammals

A set of chemical transformations of substances from the moment of entering the body before excretion is called metabolism. This is a necessary condition for the growth, development and simple existence of any living organism. Different groups of mammals have adapted differently to the extraction of food. Predators attack the weaker animals. For this, they have well-developed teeth, namely incisors and canines. Many also herbivorous and insectivorous species. Of particular interest are ruminant animals. Their digestive system is especially complex. Incisors from the top are completely absent, they are replaced by a transverse dental roller, and the fangs are underdeveloped. Such a structure of the teeth is necessary to chew the grass - the chewing gum. Giraffes, cows and deer are typical representatives of this group of animals. Their stomach consists of four sections. They bear the names of the scar, the net, the book, the abomasum. In the first two chewed food breaks up into solid and liquid parts. The chewing gum regurgitates from the stomach back into the mouth and is chewed again. Then carefully processed food immediately falls into the third department - a book, and from there - into the abomasum. In this last section, it is already exposed to the action of gastric juice and is finally cleaved.

Non-ruminant animals, such as wild boars, pigs and hippos, have a simple single-chamber stomach and a standard digestive system.

To capture food, some mammals use limbs. So, the elephant puts food in the mouth with the help of a trunk. And bats that eat nectar have a flattened snout and tongue in the shape of a tassel. A special device is also available for food. Many rodents store grains in cheek pouches.

The digestive system of mammals has a complex structure, the characteristics of which depend on the nature of food and the habitat of animals.