Length of intestine

The intestine is the department of the digestive system in most vertebrates. He follows directly behind the stomach. In the intestine, the final digestion of the food taken, the absorption of nutrients, and the removal (evacuation) of undigested substances are carried out.

In some animals, the digestive tract consists only of this department. In this case, the length of the intestine depends on the type of animal, the characteristics of food used and age.

The most primitive closed structure of this department of digestion is observed in flatworms and coelenterates (colonial cnidaria). The second have a single gastrovascular cavity, through which there is a metabolism between the individual that feeds, and other members of the colony. Flatworms have one opening for food and waste disposal.

Invertebrates (insects, mollusks) have an intestine consisting of three sections (anterior, posterior and middle gut). The front part includes the mouth, the goiter, the pharynx, the esophagus, the anus and the rectum are in the back part, in the middle - actually, the intestine, the Malpighian vessels, the stomach. Some coral polyps have an outwardly curving intestine. Digestion, thus, is carried out external.

Larvae of lampreys and lancelets have a fairly straight and small bowel. The organ begins immediately after the oropharyngeal cavity. The length of the intestines of adult lampreys is small (not more than the body itself). The organ starts right after the esophagus, has a valve in the form of a spiral. Due to this screw-like longitudinal fold, the area of absorption and digestion increases. A spiral valve is present in sturgeons and sharks.

In many vertebrates, the length of the intestine allows it to be divided into sections - the straight, thick and small intestine. This body displays the secrets of the pancreas and liver. At the beginning of the intestine of bone fish are located pyloric appendages (blind processes). Their number may be different. Amphibians have a duodenum, and a rectum opens into the cloaca.

The terrestrial herbivorous reptiles have a well developed cecum. It is located on the border of a thick and thin department. The length of the intestine (thin) of birds is several times the length of the body. From the back department, opening into the cloaca, it is separated by two blind outgrowths. There is no rectum and large intestine.

Herbivorous animals have a fairly long intestine. The blind and thick sections are well developed. The length of the large intestine in rodents can reach 53% of the total length of the entire intestine. Predators are much shorter. For example, a sheep has an intestine whose length exceeds the body length by 29-35 times, the boar at 14, the horse at 12, and the wolf at 6. The thick section is inhabited by a symbiotic microflora that is most well developed in herbivores.

The human intestine is the largest organ of the digestive system. It starts from the stomach and ends with the anal opening (anus). The food mass is advanced by means of peristalsis (wave-like contractions). In the process of digestion, the microorganisms in the organ and its microflora are involved. In this part of the digestive tract, not only digestion is carried out, but also the absorption of useful elements from food, the synthesis of individual hormones, and the immune processes.

In life, the length of the intestine in a person (adult) is about four meters. At the time of birth, it is about three meters, which is more than the height of a newborn on average six times. The length of the human intestine after death increases and is about seven to eight meters. This is due to relaxation of the muscles after death.