They have a three-chambered heart. Congenital heart defects. Computed and magnetic tomography

home The same organs different types

may differ in structure and functionality. Our own heart has four separate chambers, while frogs, toads, snakes and lizards can get by with just three. You can learn about the functionality of three-chambered hearts in this article.

Vertebrate classes and cardiac chambers Vertebrates presented different classes : fish, amphibians, reptiles, mammals and birds. In vertebrates, the heart performs blood pumping function

throughout the body this is called blood circulation. Although the circulatory systems are similar in many ways, the hearts of different classes of vertebrates have different numbers of chambers. These chambers determine how efficiently the heart carries oxygen-rich blood and oxygen-poor blood back to the heart.

• Vertebrates can be divided by the number of heart chambers:
• Two chambers: one atrium and one ventricle (fish)
• Three chambers: two atria and one ventricle (amphibians, amphibians and reptiles)

Four chambers: two atria and two ventricles (birds and mammals)

Circulation The most vital substance, oxygen, enters the blood through the gills or lungs. To achieve more efficient use of oxygen, many vertebrates have two separate stages of blood circulation

: pulmonary and systemic.

In chamber pulmonary circulation, the heart sends blood to the lungs to enrich it with oxygen. The process begins in the ventricle, from there, through the pulmonary arteries, it enters the lungs. Blood returns from the lungs through the pulmonary veins and flows into the left atrium. From there it enters the ventricle, where the systemic circulation begins.

The circulatory system distributes oxygen-rich blood throughout the body. The ventricle pumps blood through the aorta, a massive artery that branches throughout the body. Once oxygen is delivered to the organs and limbs, it is returned through the veins, which lead it to the inferior vena cava or superior vena cava. Then from these two main veins it enters the right atrium. Once there, the oxygen-depleted blood returns to the pulmonary circulation. The heart is a complex pump and main body circulatory system

, ensuring the enrichment of the body with oxygen.: atrium and ventricle. One on each side, each with different functions. The left side provides systemic circulation, while the right side of the heart is responsible for pulmonary circulation, that is, for oxygenation.

Atria

The atria are the chambers through which blood enters the heart. They are located on the front side of the heart, with one atrium on each side. The right atrium receives venous blood through the superior vena cava and the inferior vena cava. The left one receives oxygenated blood from the lungs through the left and right pulmonary veins.

Blood flows into the atrium, bypassing the valves. The atria relax and dilate as they fill with blood. This process is called diastole fibrillation, we are with you we call it pulse. The atria and ventricles are separated by the mitral and tricuspid valves. The atria pass around atrial systole, creating brief atrial contractions. They, in turn, push blood from the atria through the valves and further into the ventricles. The elastic tendons that attach to the ventricular valve relax during ventricular systole and move into ventricular diastole, but the valve closes during ventricular systole.

One of the defining characteristics of the atria is that they do not interfere with venous blood flow to the heart. Venous blood entering the heart has very low pressure compared to arterial blood, and the valves take over the venous blood pressure. Atrial systole is incomplete and does not block the flow of venous blood through the atria into the ventricles. During atrial systole, venous blood continues to flow continuously through the atria into the ventricles.

Atrial contractions are usually minor, only preventing the significant backpressure that prevents venous blood from flowing. Atrial relaxation is coordinated with the ventricle to begin relaxing before the ventricles begin to contract, which helps prevent the heart rate from becoming too slow.

Ventricles

The ventricles are located at the back of the heart. The ventricle receives blood from the right atrium and pumps it through the pulmonary vein into the pulmonary circulation, which enters the lungs for gas exchange. It then receives oxygen-rich blood from the left atrium and pumps it through the aorta into the systemic circulation to supply the body’s tissues with oxygen.

The walls of the ventricles are thicker and stronger than those of the atria. The physiological loads that pump blood throughout the body from the lungs are much greater than the pressure created to fill the ventricles. During ventricular diastole, the ventricle relaxes and fills with blood. During systole, the ventricle contracts and pumps blood through the semilunar valves into the systemic circulation.

People are sometimes born with congenital anomalies, in the form of a single ventricle with two atria. Rudimentary parts of the ventricular septum may be present but not functional. The disease is called heart disease.

The only species of amphibian that has 4 chambers of the heart is the common crocodile. A number of animals have three chambers, that is, two atria and one ventricle.

• amphibians
• amphibians
• reptiles.

In nature, amphibians and most reptiles have a prechamber heart and consist of two atria and one ventricle. These animals also have separate chains of blood vessels, where separate chambers are responsible for oxygen saturation, and the venous chamber returns and flows into the right atrium. From there, blood is conducted to the ventricle and then pumped to the lungs. After being enriched with oxygen and freed from carbon dioxide, the blood returns to the heart and flows into the left atrium. Then it enters the ventricle a second time and is further distributed throughout the body.

The fact that these are cold-blooded animals, their bodies do not expend much energy to produce heat. Thus, reptiles and amphibians can survive with less efficient heart structures. They also capable of blocking the flow in the pulmonary artery to divert blood to the skin for cutaneous respiration during diving. They are also capable of shunting blood flow in the pulmonary artery system during a dive. This anatomical function is considered the most complex among cardiac structures in vertebrates.

All vertebrate animals such as fish, amphibians, reptiles, birds, and mammals use oxygen from the air (or dissolved in water) to effectively extract energy from food and emit carbon dioxide as a waste product.

Any organism must deliver oxygen to all organs and collect carbon dioxide. We know that this specialized system called the circulatory system: it consists of blood, they contain cells that carry oxygen, blood vessels(the tubes through which blood flows), and the heart (the pump that pumps blood through the blood vessels).

Although everyone thinks that fish only have gills, it is worth noting that many species also have lungs. In many fish, the circulatory system is a relatively simple cycle. The heart consists of two contractile chambers, the atrium and the ventricle. In this system, blood from the body enters the heart and is pumped through the gills, where it is enriched with oxygen.

To answer the question of how this phenomenon appeared, we must first understand what was behind the formation of such a complex shape of the heart and circulatory system during evolution.

About 60 million years, from the beginning of the Carboniferous period to the end Jurassic period, amphibians were the dominant land animals on the ground. Soon, due to their primitive structure, they lost their place of honor. Although among the various families of reptiles that descended from amphibians, isolated groups were more resilient. For example, archosaurs (which eventually evolved into dinosaurs) and therapsids (which eventually evolved into mammals). The classic amphibian was the big-headed Eryops, which measured about fourteen meters in length from head to tail and weighed about two hundred kilograms.

Word "amphibian" in Greek means "both types of life", and that pretty much sums up what makes these vertebrates unique: they lay their eggs in water because they require a constant source of moisture. But they can live on land.

Great progress in the evolution of vertebrates has given many species circulatory and respiratory systems, highly efficient. According to these parameters, amphibians, amphibians and reptiles are located at the bottom of the oxygen-respiratory ladder: their lungs have a relatively small internal volume and cannot process as much air as the lungs of mammals. Fortunately, amphibians can breathe through their skin, which, coupled with a three-chambered heart, allows them, albeit with difficulty, to fulfill their metabolic needs.

In the course of evolution, the blood system became more complex. From the moment the heart appears, the number of its chambers increases, and the vessels extending from it are differentiated. A three-chambered heart provides organisms with a number of advantages over a more simply constructed organ. Animals have higher vital energy.

Complication of the structure of the heart

The anterior part of the abdominal vessel pulsates in the lancelet.

In fish, the heart already consists of one atrium and one ventricle.

Who has a three-chambered heart? In amphibians, the atrium has two parts that open into the ventricle with a common opening.

This is also typical for reptiles. Already in lizards, snakes, turtles and crocodiles, each atrium has an independent opening that opens into the ventricle. The holes have valves. Reptiles, like amphibians, have a single ventricle, but it is divided by an incomplete septum that grows from bottom to top.

Birds and animals that feed their young with milk have two atria and the same number of ventricles. Both the atria and ventricles are completely separate from each other.

From the above list it is clear that a three-chambered heart is characteristic of amphibians and reptiles. However, the structure still differs not only among the classes of these animals, but also between genera. Thus, in crocodiles the septum between the back parts of the heart is almost complete. Despite this fact, crocodiles remain cold-blooded animals, because blood containing a large percentage of carbon dioxide enters the main arterial trunk. Mixed blood flows through the vessels leading to the body.

Outgrowths in the ventricle of the heart as the beginning of the formation of a septum

Those with a three-chambered heart have pulmonary and systemic circulations. This increases general level life. Moreover, those who have a three-chambered heart have a tendency to form outgrowths in the ventricle. The frog already has numerous protrusions, which significantly separates the arterial blood from that in which there is a high content of carbon dioxide. However, tadpoles have a single blood circulation.

The structure of the three-chambered heart of a frog

Amphibians have a heart with three chambers.

The ventricle has thick walls. The atria communicate with the ventricle through a common opening. The right atrium is larger in volume. It receives blood from all over the body, which has given off an element of oxidation. To the left side of the heart there's blood coming out from the lungs. The venous sinus is connected to the right atrium. It pumps blood to the heart. WITH right side there is an arterial cone. It is also present in lower fish. Includes a number of valves. Serves to pump blood into vessels. In amphibians, the cone is divided into two sections by a septum.

Diagram of blood flow in the heart of a frog

Blood with a high content of carbon dioxide mixed with oxygenated blood flows into the right atrium, and only enriched with an element for oxidation into the left atrium. The atria contract simultaneously. The blood passes into a single ventricle. Here the outgrowths prevent strong mixing of the blood. The conus arteriosus extends to the right of the ventricle, so blood containing large quantity carbon dioxide. It fills the cutaneous pulmonary arteries. The cone has a spiral valve. As blood pressure increases, it moves, opening the opening of the aortic arches. Mixed blood rushes here from the middle part of the ventricle. Next, the blood pressure increases even more, and the spiral valve opens the mouths of the carotid arteries, which go to the head. Blood flows into the carotid arteries, since the remaining vessels are already filled.

Circulatory system of lizards and other reptiles

In lizards and snakes, the two circulations are not completely separated. But the degree of their separation is higher than that of amphibians. Two aortic arches are preserved. The ventricle has a wall, but it does not completely separate into two halves. It is believed that crocodiles have a four-chambered heart. Although the hole between the ventricles still remains.

Thus, with a three-chambered heart they have greater mobility compared to fish. They can go to land, where they feel great. Life activity has increased evolutionarily.

Individuals with a three- and four-chambered heart always have two circles of blood circulation, which also greatly increases the mobility of organisms. And for land vertebrates this is necessary in conditions where holding the body is many times heavier than in aquatic environment. With two circulations, the oxygen-carrying blood is under sufficient pressure as it passes through the heart again. And it does not mix with the venous one.

Some frogs come out of hiding in early spring, when the snow has not yet melted. One of the first to appear in middle lane grass frogs.

Those with a three-chambered heart have greater mobility in cold conditions than other cold-blooded representatives.

For answers to tasks 29-32, use a separate sheet. First write down the number of the task (29, 30, etc.), and then the answer to it. Write down your answers clearly and legibly.

INFLUENCE OF ALCOHOL ON THE HUMAN BODY

Alcohol ( ethanol) destroys the physical and mental health person. It acts on the nervous system, disrupting the regulation of all organ systems, and changes human behavior.

From the stomach, alcohol enters the bloodstream within 2 minutes and spreads throughout the body. It is known that malfunctions nervous system and internal organs are associated with blood alcohol concentration.

At a blood alcohol concentration of 0.04%, cells in the cerebral cortex are affected. A person loses the ability to control his body and behavior.

Excitation processes in the cortex cerebral hemispheres begin to dominate the inhibition processes. A person loses restraint and modesty. He says and does things he would never say or do when sober.

At a blood alcohol concentration of 0.1%, deeper parts of the brain are inhibited. A staggering gait appears, movements become uncertain and fussy. A person’s ability to hear and visually perceive is weakened. Impaired eye movement causes objects to appear double. Loss of control over the muscles of the tongue will make speech difficult.

A blood alcohol concentration of 0.2% affects areas of the brain that control a person's emotional behavior. At the same time, base instincts awaken and sudden aggressiveness appears.

With a blood alcohol concentration of 0.3%, a person does not understand what he sees and hears. A blood alcohol content of 0.4% leads to loss of consciousness and involuntary emptying of the bladder. There is no sensitivity. At a concentration of 0.6-0.7% death occurs.

Alcohol is the cause of many misfortunes: car accidents, injuries and mutilations, loss of productivity and family, loss of spiritual needs, will and human appearance. More than 50% of crimes are committed while intoxicated. Alcohol is eliminated from the body only after 2 days, so people who drink half a liter of beer or wine a day do not recover from a state of chronic alcohol poisoning. Alcoholism develops as a result of frequent drinking.

Alcoholism is a disease characterized by an uncontrollable desire to drink alcohol, mental and physical disorders, and personality degradation.

The definition of youth beer alcoholism was given by the first Reich Chancellor of Germany, Bismarck: “Beer makes people lazy, stupid and powerless.” Boys and girls should remember that beer contains excess carbohydrates and disrupts metabolism, which leads to obesity. Beer contains plant analogues of female sex hormones, which in men causes atrophy of the genitals and growth of the mammary glands and indifference to the opposite sex. People suffering from alcoholism neglect their children, family, responsibilities, and friends in order to satisfy their destructive need for alcohol. Their children pay for their parents' alcoholism. Most congenital deformities, mental disorders, physical and mental retardation mental development is a consequence of parental alcoholism.

1) Why does drinking beer cause atrophy of the gonads, growth of mammary glands and indifference to the opposite sex in men?

2) Is it possible to die from drinking alcohol?

3) What is the cause of most congenital deformities, mental disorders, and retardation in physical and mental development?

Show answer

The correct answer must contain the following elements:

1) Beer contains plant analogues of female sex hormones, which lead to such consequences.

2) Yes. At a blood alcohol concentration of 0.6-0.7%, death occurs. Possible death from car accidents, injuries and injuries received while intoxicated.

3) In most cases, the cause is parental alcohol abuse.

Using the table “Maximum life expectancy of different types of vertebrates,” answer the questions and complete the task.

1) Which of the mammals presented in the table has the longest life expectancy?

2) Which bird will live the longest in the zoo?

3) Does the lifespan of an animal depend on its size?

Show answer

The correct answer contains the following elements:

1 person

3) Depends. The larger the animal, the longer it lives.

When choosing, keep in mind that Natalya drinks tea with one spoon of sugar and loves waffle cones.

In your answer, indicate the calorie content of dinner for four meals a day, the ordered dishes that should not be repeated, their energy value, which should not exceed the recommended calorie content of the dinner, and the amount of carbohydrates in it.

If a frog came to you for advice on whether it should change its three-chambered heart to a four-chambered one or a two-chambered one (by removing the septum between the atria), what would you advise it?

The frog should be advised to preserve its three-chambered heart. A two-chambered heart would be disadvantageous for a frog for the following reasons. With a three-chambered heart, blood carrying oxygen from the lungs enters the left atrium. Venous blood from muscles, internal organs, etc. enters the right atrium (blood from the skin also enters there). With simultaneous contraction of the atria, blood enters the single ventricle of the frog, but mixes little in it, since the ventricle contains a number of partitions and resembles a sponge in its structure. As a result, mixed blood, rather poor in oxygen, appears in the right half of the ventricle, and oxygen-rich blood in the left half. The analogue of the aorta (conus arteriosus) arises from the right side of the ventricle. The cone contains a special so-called spiral valve. Vessels carrying blood to the lungs and skin extend from the initial part of the cone; then the vessels going to the body and limbs depart; Vessels carrying blood to the brain and sensory organs located on the head extend even further. When the ventricle begins to contract, the pressure in it is still low, the spiral valve opens only the opening of the vessel going to the lungs and skin, and blood from the right half of the ventricle, poor in oxygen, begins to flow there. As the ventricle contracts, the pressure in it increases, and the spiral valve opens the opening of the next vessel; blood richer in oxygen flows to the body and internal organs. Finally, when the pressure increases further, the entrances to the carotid arteries, carrying blood to the head, will open. The most oxygen-rich blood will flow there from the left part of the ventricle, which is furthest away from the conus arteriosus. This blood only to a small extent enters other vessels, which were previously filled with previous portions of blood.
Thus, despite the presence of only one ventricle, the frog has a system for the expedient distribution of blood, enriched with oxygen to varying degrees, between the lungs, internal organs and the brain. If you remove the septum between the atria and make the heart two-chambered, then the blood coming from the lungs and venous blood will mix in this common atrium, which will significantly worsen the functioning of the circulatory system. The same mixed blood will enter the lungs as the brain. The efficiency of the lungs will decrease, the frog will receive less oxygen on average, and its activity level should also decrease. The brain will be especially affected, as it will begin to receive blood that is much poorer in oxygen.
Let us now consider the question of a four-chambered heart. It is easy to realize that in animals with a four-chambered heart, all the blood coming from the body must pass through the lungs, from where it returns to the second atrium. If the pulmonary vessels of a mammal or bird are blocked, all blood flow will stop. Frogs spend a significant part of their lives in water, in particular they spend the winter there. While underwater, the frog with a three-chambered heart can reduce the lumen of the pulmonary vessels and thereby reduce the flow of blood through the inactive lungs; in this case, the blood ejected from the ventricle into the pulmonary cutaneous artery enters mainly the skin and returns to the right atrium.
If the frog's heart were four-chambered and its pulmonary circulation was completely isolated, then this would be unprofitable. The frog would have to pump all the blood through the inactive lungs all winter, spending a noticeable amount of energy on this, which cannot be replenished in winter, and therefore, it would be necessary to accumulate additional reserves before wintering. Thus, a three-chambered heart is indeed most suitable for a frog with its amphibian lifestyle and important role skin respiration.

You will learn which vertebrates have a three-chambered heart in this article.

What animals have a three-chambered heart?

Amphibians ( amphibians) and reptiles ( reptiles or bastards) have a three-chambered heart and two circles of blood circulation.

Heart of an adult frogs three-chambered, consisting of a ventricle and two atria.

The three-chambered heart consists of two atria and one ventricle. (the crocodile is said to have a four-chambered heart), but the septum dividing the heart is incomplete, leaving a hole between the two chambers. Blood from the ventricle enters one of two vessels. It travels either through the pulmonary artery to the lungs or through the aorta to the rest of the body. Oxygen-enriched blood travels from the lungs to the heart and through the pulmonary vein to the left atrium. And the blood from carbon dioxide, returning from the body, enters the right atrium through the venous sinus. Both atria empty into one ventricle, mixing oxygenated blood coming from the lungs with oxygen-deprived blood coming from body tissues.

Although this system ensures that blood always flows to the lungs and then back to the heart, mixing blood in the same ventricle means that the organs do not receive oxygenated blood.