The special structure of the crocodile's heart can help it with digestion. Crocodile body structure How many circles of blood circulation does a Nile crocodile have?

The crocodile has always been a strange animal for us. Therefore, dream interpreters attributed his appearance in a dream to a variety of reasons.

There is a version that seeing a crocodile in a dream and being happy is a sign that the girl will receive advantageous offer about marriage.

In general, a crocodile is a formidable and dangerous animal. If anything happens, he won’t spare you.

Therefore, of course, seeing him in a dream is a sign of the threat of a collision with a dangerous enemy who can cause you a lot of pain and trouble, or even take your life.

Sometimes such a dream means that close friends will betray you, after which you will stop trusting people altogether.

Often such a dream serves as an indication that you have made a mistake in your affairs, and your enemies will not fail to take advantage of it to grind you into powder.

Being dangerously close to a crocodile in a dream means that you will be drawn into an unpleasant story fraught with bad consequences.

The peculiarity of such a dream is that in the situation about which we're talking about, you will have to rely only on your own strength.

Seeing him at the zoo is a sign that you may soon find yourself in an unusual situation. Sometimes such a dream predicts long journey.

If you dream that a crocodile is going to attack you, then your enemies are going to laugh at you.

Interpretation of dreams from the Family Dream Book

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Dream Interpretation - Crocodile

A crocodile seen in a dream foretells that you will soon be deceived by your closest friends. Yes, in fact, enemies can become active at the most unexpected moment.

If you dreamed that you were walking on the back of a crocodile, you are facing troubles that you will stubbornly fight, trying to get out of them on your own. You will succeed if you try to avoid excessive frankness when communicating with people.

Interpretation of dreams from

Answer from Lenzel[guru]
Not being able to chew prey with its powerful but rather primitive jaws, the crocodile tears it into pieces in advance and sends it into the stomach in huge pieces.
The total mass of prey can be up to a fifth of the animal’s own weight. Of course, these reptiles are far from their related pythons, but it’s hard to imagine a person capable of peeling 15 - 20 kilograms in one sitting raw meat, and even with bones, it’s quite difficult.
The crocodile's heart is four-chambered, but the circles of circulation are not completely separated. In addition, not only the pulmonary artery departs from the right ventricle, but also an additional, so-called left artery, through which most of the blood is directed to the digestive system, primarily to the stomach. Between the left and right arteries (the right one comes from the left ventricle) there is a foramen of Panizza, which allows venous blood to enter the beginning of the systemic circulation - and vice versa.
In humans, this is an anomaly and is called birth defect hearts. The crocodile not only does not feel the defect here, but also has an additional mechanism that allows it to artificially pump oxygen-poor blood into the right artery. Or completely close the left artery, while its circulatory system will work almost the same as in mammals. The crocodile can control this so-called toothed valve at will. The reasons that prompted nature to create such a remarkable mechanism have long occupied scientists. For a long time it was believed that the crocodile heart was a transitional stage on the way to the full-fledged four-chamber heart of warm-blooded mammals.
However, there was an opposite point of view, according to which the crocodile is a descendant of a warm-blooded animal, which, for evolutionary reasons, became more profitable to live the life of a cold-blooded killer. This heart structure can be very useful for a semi-submersible lifestyle: the decrease in oxygen in the blood can slow down the metabolism, which helps in long dives when a predator waits motionless for its prey. Thanks to this complex system a crocodile can quickly decompose pieces of prey it swallows.

In her opinion, the fact is that this blood is rich in carbon dioxide. When the crocodile sends CO2-rich blood to the stomach and other digestive organs, special glands use it to produce gastric juice, and the more it reaches them carbon dioxide, the more active the secretion. It is known that in the intensity of secretion of gastric juice by their glands, crocodiles are ten times higher than the champions in this indicator among mammals. This allows not only to digest food, but also to suppress growth harmful bacteria in the stomach.
But a crocodile cannot hesitate: if a fish, a monkey, or even a human leg is not digested too quickly, the reptile will die. Either in the mouth of another predator due to its clumsiness, or from hunger and intestinal upset: in a hot climate, bacteria multiply very quickly on a swallowed piece of meat in the belly of an animal. It turned out that in a crocodile that had just eaten, for many hours the valve actually causes blood to flow predominantly bypassing the lungs. Source: Also, after feeding in crocodiles whose left aorta was blocked, the production of gastric juice was significantly reduced - despite the fact that the blood continued go to digestive organs in sufficient quantities through the right aorta. At the same time, the ability of crocodiles to decompose bones, which make up a significant part of their diet, also sharply decreased. For a crocodile, a rich meal almost always follows a dash for prey, during which the usually clumsy animal instantly jumps out of the water, grabs the prey that is ungainly at the watering hole and drags it under the water. At this time, such an amount of toxic lactic acid is generated in the muscles (it is because of them that after physical activity muscle aches), which can cause the death of the animal. According to scientists from Utah, this acid is also transported through the blood to the stomach, where it is utilized.

Reply from Victor Richert[guru]
like everyone else it's warm

Reply from No[newbie]
cold and slippery

Reply from Marina K[guru]
Big and good! And so soulful! “Crocodile tears” are from emotions!

Reply from Andro Gil[guru]
delicious00000

Reply from Photographer[guru]
Four-chamber

Reply from Natasha[guru]
It has four chambers, but the circles of circulation are not completely separated. In addition, not only the pulmonary artery departs from the right ventricle, but also an additional, so-called left artery, through which most of the blood is directed to the digestive system, primarily to the stomach. Between the left and right arteries (the right one comes from the left ventricle) there is a foramen of Panizza, which allows venous blood to enter the beginning of the systemic circulation - and vice versa.
In humans, this is an anomaly and is called congenital heart disease. The crocodile not only does not feel the defect here, but also has an additional mechanism that allows it to artificially pump oxygen-poor blood into the right artery. Or completely close the left artery, while its circulatory system will work almost the same as in mammals. The crocodile can control this so-called toothed valve at will.
The reasons that prompted nature to create such a remarkable mechanism have long occupied scientists. For a long time it was believed that the crocodile heart was a transitional stage on the way to the full-fledged four-chamber heart of warm-blooded mammals.
However, there was also an opposite point of view, according to which the crocodile is a descendant of a warm-blooded animal, which, for evolutionary reasons, became more profitable to live the life of a cold-blooded killer. In this case, the Panizza foramen and the serrated valve turn out to be an adaptation mechanism that allowed the transition to a cold-blooded existence. For example, in 2004, Roger Seymour from the Australian University of Adelaide and his colleagues showed that such a heart structure can be very useful for a semi-submersible lifestyle: a decrease in oxygen content in the blood can slow down the metabolism, which helps in long dives when a predator waits motionless for its kill. sacrifice.

Among the most dangerous predators in the world, one of the first places are crocodiles (Latin name - Crocodilia) - the only surviving heirs of dinosaurs, which belong to the order of aquatic vertebrates. Average length an adult individual is from 2 to 5.5 meters, and the mass of a crocodile can reach 550-600 kilograms.

External structure of a crocodile

The structural features of crocodiles, both internal and external, help them survive in incredible conditions. It is interesting that, despite the long process of evolution, these reptiles have retained almost all the features of their ancestors, in particular the body of a crocodile , adapted to aquatic environment habitat:

Few people know that the body of a crocodile can have different colors, although, as a rule, the color of a crocodile is greenish-brown. Upper part skin consists of rows of extremely strong and tightly connected horny plates that grow along with the individual itself, so that they do not shed. The color of crocodile skin can vary depending on external factors, or rather temperature environment. These animals are cold-blooded, therefore normal temperature The crocodile's body angle varies between 30 and 35 degrees.

Crocodile teeth

Representatives of this species are often confused with alligators, although in reality they have a number of differences, the main of which is the location and structure of the dentition. For example, if the jaws of a crocodile are closed, you can see the 4th tooth from the bottom, whereas in an alligator they are all closed. Total number A crocodile has 64 to 70 teeth, depending on the variety, and they have the same conical shape and a hollow inner surface where new incisors develop. On average, each crocodile's fang is replaced once every two years, and over the course of a lifetime there can be up to 45-50 such updates. In turn, the crocodile’s tongue is completely fused to the lower jaw, so some generally think that reptiles do not have this organ.

Despite the fact that the crocodile's mouth looks very scary, in fact its teeth are not designed for chewing food, so it swallows its prey in large pieces. The digestive system of a crocodile has a number of specific features, for example, the stomach has very thick walls, and to improve digestion it contains stones (gastroliths). Their additional function– change the center of gravity to improve swimming performance.

Features of the internal structure of crocodiles

Generally, internal structure the crocodile is similar in structure to other reptiles, but there are some unusual features. For example, the skeleton of a crocodile is very similar to the structure characteristic of dinosaurs: two temporal arches, a diapsid skull, etc. The most vertebrae are found in the tail (up to 37), while in the cervical region and trunk there are only 9 and 17, respectively. For additional protection, there are ribs in the abdominal part that are not connected to the spine.

The crocodile's respiratory system is created in such a way that the animal feels comfortable both on land and under water. The crocodile's respiratory organs are represented by the choanae (nostrils), the nasopharyngeal passage with a secondary bony palate, the palatine curtain, the trachea and the lungs with the diaphragm. The very powerful and complex lungs of a crocodile are capable of holding a large volume of air, while the animal can, if necessary, adjust its center of gravity. To prevent the crocodile's breathing from interfering with its ability to move quickly, there are special muscles in the diaphragm area.

The crocodile’s circulatory system is unique in its own way, which is much more advanced than that of other reptiles. Thus, the crocodile’s heart is four-chambered (2 atria and 2 ventricles), and a special mechanism for mixing blood from arteries and veins makes it possible to regulate the blood supply process. If you need to speed up the digestion process, the structure of the crocodile’s heart allows you to change arterial blood to venous blood, which is more saturated with carbon dioxide and promotes the production of additional gastric juice. It should also be noted that crocodile blood has a high content of antibiotics, and hemoglobin is saturated with oxygen and works independently of red blood cells.

By the way, these predators do not have a bladder, and to search for a mate during the breeding season, there are special glands on the lower half of the jaw, which emit a musky odor.

Their nervous system is very developed, in particular, the crocodile’s brain (or rather, cerebral hemispheres) is covered with bark, and among the sensory organs, hearing and vision are especially developed. We can say with confidence that the crocodile’s memory is very good, since it manages to remember the paths along which other animals go to the watering hole.

I'll tell you a story that happened a few years ago. Now I am writing a school textbook on zoology according to a program in which I myself participated. When this version of the program was first conceived, I convinced the ministerial official that before systematic study separate groups you need to consider a fairly large topic that will talk about animals in general.

“Okay, where should I start?” - the official asked me. I said that the way animals live is determined primarily by what they eat and how they move. This means we need to start with a variety of ways of eating. “What are you talking about!” my interlocutor exclaimed. “How can I take such a program to the minister? He will immediately ask why we instill in children that the most important thing is food!”

I tried to argue. In general, the division of living organisms into kingdoms (animals, plants, fungi and others) is associated primarily with the method of nutrition, which, in turn, determines the features of their structure. The characteristics of multicellular animals are a consequence of the fact that they need external sources organic matter and at the same time they do not absorb them through the surface of the body, but eat them in pieces. Animals are creatures that eat other organisms or their parts! Alas, my interlocutor was adamant. The minister will be primarily interested in the educational aspect of the program.

Thinking about how to organize the introductory part differently, I then made an unforgivable mistake. My next idea was the proposal to start studying the zoology course with diversity life cycles. When my interlocutor realized that I was going to consider reproduction, not food, as the “main thing in life”, he seemed to think that I was making fun of him... In the end I wrote something that, as I hoped, no one won't be shocking. Then methodologists worked their magic on this program, corrected everything in it that they did not understand, and replaced the formulations with those that were in use in historical eras, when these same methodologists studied at pedagogical institutes. Then officials corrected the ill-fated program, then it was rethought in the spirit of new guidelines, then... - in general, I’m writing a textbook on my “own” program and I don’t get tired of swearing.

And I remembered this sad story because I was once again convinced: the most important thing for animals is the notorious “food”. When we compare different groups of our relatives with each other, we often do not realize what characteristics led them to success or failure. Do you know, for example, what has become one of the main trump cards of mammals? A successful schoolchild will name feeding offspring with milk, warm-bloodedness, high development nervous system or some other property that is made possible by sufficient energy obtained from food. And one of the main trump cards of mammals is the structure of the jaws and teeth!

Try moving your lower jaw: up and down, left and right, back and forth. Its “suspension” allows movement in all three planes! In addition, on the jaws of mammals there are teeth, the structure of which is determined by the task assigned to them - to pierce, crush, grind, cut, crush, bite, tear, hold, gnaw, crush, pry, grind, scrape, etc. Our jaws are an evolutionary biomechanical masterpiece. Apart from mammals, almost no land vertebrates are capable of biting off pieces of food! A few exceptions include the archaic hatteria, which can saw off the head of a petrel chick with its jaws, and turtles, which abandoned teeth in favor of a horny scissor-shaped beak. AND birds of prey, and crocodiles do not bite off pieces of food, but simply tear them off - resting with their claws (the first) or spinning with their whole body (the second).

By the way, about crocodiles - this column is dedicated primarily to them. Thanks to sophisticated experiments, biologists from the University of Utah were able to learn something new about the functioning of the heart of these reptiles. But first, a few more words about school biology.

Some feeding features biological material have been preserved from those times when the school was supposed to form a materialistic worldview, promoting evolution. Generally speaking, the fact of evolution has no special treatment to the “materialism-idealism” dilemma (while verbally rejecting mossy diamat, for some reason we still attach excessive importance to this dubious dichotomy). Alas, when instead of modern ideas about evolution some stale dogmas are taught, this only causes damage to the natural scientific worldview. Such dogmas include the linear view of evolution. Think about it, the history of vertebrates is a “bush” of many branches, each of which followed its own path, adapted to its own way of life. A school teacher, jumping from branch to branch of this bush, builds a progressive sequence of “typical representatives”: lancelet-perch-frog-lizard-dove-dog. But the frog never tried to become a lizard, it lives its own life, and without taking into account this life (and the background history of frogs) it is impossible to understand it!

What will the school teacher tell you about crocodiles? He uses them to illustrate the statement that the most progressive animals are those with a four-chambered heart and “warm-blooded” (homeothermic). And - look, children! - a crocodile has a four-chambered heart, almost like those of mammals and birds, but there is only one extra hole left. We see with our own eyes how the crocodile wanted to become a man, but did not get there, stopping halfway.

So, the crocodile has a four-chambered heart. From its right half, blood goes to the lungs, from the left - to the systemic circulation (to the organs that consume the oxygen received in the lungs). But between the bases of the vessels extending from the heart there is a gap - the Panizzian foramen. During the normal operation of the heart, part of the arterial blood passes through this hole from the left half of the heart to the right half and enters the left aortic arch (look at the picture so as not to get confused in the right-left relationship!). Vessels leading to the stomach depart from the left aortic arch. The right aortic arch departs from the left ventricle, supplying the head and forelimbs. And then the aortic arches merge into the dorsal aorta, which provides blood supply to the rest of the body. Why is it so difficult?

First, let’s figure out why we need two circles of blood circulation at all. Fish make do with one thing: heart - gills - consumer organs - heart. Here the answer is clear. The lungs will not be able to withstand the pressure required to pump blood through the entire body. This is why the right (pulmonary) half of the heart is weaker than the left; That is why it seems to us that the heart is located in the left side of the chest cavity. But why does part of the blood flowing through the systemic circulation (from the left half of the heart) pass through the right, “pulmonary” part of the heart and the left aortic arch in crocodiles? In humans, incomplete separation of blood flows can be caused by heart disease. Why do crocodiles need such a “vice”? The fact is that the heart of a crocodile is not an unfinished human heart, it is “conceived” more complex and can function in two different modes! When the crocodile is active, both aortic arches carry arterial blood. But if the foramen of Panizzia is closed (and crocodiles “know how” to do this), venous blood will flow into the left aortic arch.

Traditionally, such a device is explained by the fact that it supposedly allows the crocodile hidden at the bottom to turn off the pulmonary circulation. In this case, venous blood is sent not to the lungs (which cannot be ventilated anyway), but immediately to the large circle - along the right aortic arch. Somewhat “better” blood will go to the head and to the front legs than to other organs. But if the lungs are disabled, is there much use in circulating the blood?

American biologists have figured out how to test the long-standing assumption that crocodiles transfer blood from one circulation to another not in order to hide, but for the sake of better digestion of food (carbon dioxide is the substrate for the production of acid by the stomach glands). Researchers have verified that in healthy young alligators, in the process of digesting food, venous, carbon dioxide-rich blood flows through the left aortic arch (the one that supplies blood to the digestive system). Then they began to interfere with the heart function of experimental crocodiles using surgical methods. In some of them, the transfer of venous blood to the left aortic arch was forcibly blocked; others underwent surgery simulating such an intervention. The effect was assessed by measuring the activity of gastric secretions and by X-ray observation of the digestion of bovine vertebrae swallowed by crocodiles. In addition, semiconductor sensors were placed in the unfortunate alligators, which made it possible to measure their body temperature. As a result of these manipulations, it was possible to convincingly confirm the hypothesis put forward - the transfer of venous blood into the systemic circulation increases the production of acid in the stomach and accelerates the digestion of food.

Crocodiles are capable of feeding on fairly large prey, swallowing the prey whole or in large pieces (remember what we said about the structure of the jaws?). The body temperature of these predators is unstable, and if they do not have time to digest their prey quickly enough, they will simply be poisoned by it. The complex structure of the circulatory system and its ability to work in two different modes is a way to activate digestion. And your purpose digestive system justifies crocodiles: a series of x-rays shows how solid bovine vertebrae “melt” in acid in the stomachs of predators!

So, now we know what is important in the life of crocodiles. What integral beings they are!

D. Shabanov. Heart of a crocodile // Computerra, M., 2008. – No. 10 (726). - pp. 36–37

Researchers from the University of Chicago explained the structural features of the circulatory system of crocodiles. In experiments with American alligators, they were able to show that the ability to let venous blood bypass the lungs to the body tissues is necessary for them to digest food. The scientists' work was published in the journal Physiological and Biochemical Zoology.

Crocodiles, like other reptiles, have preserved right and left aortic arches. However, unlike other reptiles, the crocodile's heart is four-chambered, that is, it is divided into two atria and two ventricles.

The right aortic arch departs from the left ventricle, through which oxygenated blood, after circulating through the lungs, goes to the tissues and organs. The left aortic arch arises from the right ventricle and carries venous blood containing little oxygen. At the exit from the heart, partial mixing of venous and arterial blood from the two aortic arches occurs. The mixing of venous and arterial blood is characteristic of the imperfect circulatory systems of amphibians and reptiles.

However, crocodiles can "severe" the connection between the aortic arches. In this case, venous blood from the left arch does not mix with arterial blood from the right. That is, the main blood circulation proceeds according to a pattern characteristic of mammals.

The left aortic arch leads to the crocodile's stomach. When the junction of the arches is “blocked,” venous blood flowing through the left arch goes straight there. Scientists were able to show that in the glands located in the stomach, reactions occur with the participation of carbon dioxide in the blood, resulting in the formation of bicarbonate and acid, which helps the crocodile digest the bones of its victims. The concentration of acid in the stomach of a crocodile during active digestion is more than ten times higher than the concentration characteristic of mammals.

Crocodiles are known for being able to digest huge amounts of food - up to a quarter of it own weight. If you artificially prevent venous blood from entering the stomach bypassing the lungs, the crocodile's digestion is disrupted and it cannot cope with the digestion of its usual food.

Scientists have put forward several assumptions to explain such a high concentration of acid. Firstly, the acid prevents the proliferation of bacteria, which is especially important considering that undigested food is in the crocodile’s stomach quite for a long time. Secondly, bicarbonate is necessary for crocodiles to neutralize large amounts of lactic acid, which is formed in the muscles when attacking the victim. If the blood is not “cleansed” in time, the dose of lactic acid can be fatal. "The Alternate Route" helps the crocodiles do this.

As a third possible reason scientists call the need to quickly secrete large number acids. This is especially important for young crocodiles. Digestion proceeds better in warmth, and warm places also attractive to natural enemies, of which there are many in young animals that have not reached full strength. As soon as the crocodile enters the heat, it must begin to digest its food, and to do this it needs to quickly secrete a lot of acid, for which it uses the “blocking” of the aortic arches.