No need to explain that the heart, even in the body of an animal, is the strongest muscle. And, of course, no animal can exist without it. Although there are some exceptions. This organ is different from a human because it is “modified by nature.”
The human heart is at the highest stage of development. Thanks to a system of valves and pacemakers, it is an efficient pump that supplies the entire body with blood. Thanks to the circulation of blood in the veins and arteries, the body receives nutrients obtained from food during digestion and efficient gas exchange.
Animal
If the blood does not reach the organ within a few minutes, irreversible changes in the tissues occur in this place and their death due to failure of functioning. Therefore, the animal's heart is constantly beating. The rhythm of the organ consists of successive spasms of the body. The tone of the beats corresponds to the contractions of the cavities of the heart and their diastole.
Building
As mentioned earlier, the structure of the heartanimals - this is a cone-shaped muscle. With the base of the basis cordis and the apex of the apex cordis facing cranio-ventrally. Animals have a four-chambered heart with two atria and the same number of ventricles. The atrium at the base of the organ is almost imperceptible. On the outside, the ventricles and atria are separated by a large groove. The ears protrude a little. They contain scallop-shaped muscles, which, when contracted, contribute to the expulsion of blood. The remaining area is occupied by the ventriculum (ventricles). Inside the heart is divided into two halves: the right and left atria. They do not communicate with each other.
The structure of the left ventricle of the heart in mammals
The aorta emerges from the left ventriculum, it is divided at the base into the brachiocephalic trunk and the thoracic aorta.
The brachiocephalic trunk supplies blood to the front of the torso. With the thoracic aorta, everything is much more complicated. It enters the chest cavity, then into the diaphragm and is now called the abdominal aorta, then in the region of the sacral vertebrae it exits into the middle sacral artery. But her path does not end there either, she gets into the tail part of the animal's body.
The structure of the right ventricle of the heart in mammals
The right ventricle leaves the artery to the lungs. Then it splits into two parts (stem) leading to the right side of the lung and the left side of the lung.
Circulatory system
According to the regularity of the course of blood vessels, there are those that bring blood to the heart. And those who bring.
The circulatory system is oneof the many systems in the body that are essential for the proper functioning and function of the animal's heart. Without blood vessels, organic particles contained in food could not be delivered to organs and tissues. The circulatory system also removes waste products of metabolism (toxins). These functions are identical for vertebrates and invertebrates. And the existing differences in the structure of this system between groups developed in the course of evolution.
Pet organ
The heart of pets is four-chambered. And blood circulation occurs by contractions of the valvular apparatus of the heart. Blood flows in one direction. And the walls of the heart consist of:
- inner layer of the endocardium;
- middle myocardial layer;
- outer layer of the epicardium.
Circulation and organ structure in vertebrates
The heart of vertebrates and the circulatory system consists of the same elements, that is, the heart, veins, arteries, aorta and blood vessels. There are differences in the structure of the circulatory system that took place during evolution. They mainly relate to the structure of the organ, and were associated with a displacement of the pulmonary system.
Circulation and features of the heart in protozoan vertebrates
Let's consider how the heart of chordates works. In the simplest vertebrates - fish - it consists of four chambers: the arterial cone, the ventricle, the vestibule and the venous esophagus. Blood flows from the arterial cone into the aorta. And then to the gills, where it is saturated with oxygen. Then,passing through the abdominal aorta, delivers blood to all tissues. On the contrary, blood from the veins enters the venous sinus.
Some fish have special changes in the structure of blood vessels, similar to those preserved in modern amphibians. Amphibians are thought to have evolved from these groups of fish. In the hearts of amphibians, the atrium was divided into two left, right and venous compartments, has access to the left vestibule. The contraction of the ventricles forces deoxygenated blood to be pushed out of the right atrium into the aorta and hence into many small pulmonary arteries. Oxidized blood in the right atrium enters the ventricles of the hearts of animals.
And leaves it at the end of the contraction. Blood from the right ventricle cannot enter the pulmonary arteries because they are filled with blood that was previously infused. Blood can flow through an organ several times without complete circulation around the body. This is due to the phenomenon of mixing oxygenated and deoxygenated blood in the chamber of the heart.
Amphibians
In reptiles and amphibians, the heart in the arterial cone and chamber has a special septum. With the disappearance of gills in venous amphibians and gill arch arteries, evolution created a combination of dorsal and abdominal aortas. These junctions are called the aortic arches and the entire circulation is a large pathway of blood circulation that occurs in fish. In connection with the acquisition of lungs in the respiratory function of these animals, a second circulation has developed. Called pulmonary or small.
Imperfection of the circulatory systemamphibians is to mix the blood in the chamber. The blood flowing from the lungs is not sufficiently oxygenated. It mixes with the one that flows through the tissues. And it leaves too much oxygen there. It also mixes with the blood flowing through the blood vessels in the skin, acquiring a certain amount of oxygen there. Due to the difficulties caused by the mixing of oxygenated blood with the non-oxygenated evolution of the circulatory system, she moved to separate the venous blood from the arterial pathways.
Features of reptiles
The heart of an animal of this species has a septum in the chamber, but it is incomplete. A complete septum separating the right and left chambers is located in the heart of birds and mammals. In animals of these groups, the blood does not completely mix. The arterial cone is reduced and forms only the basis of the aorta and pulmonary arteries. In order for blood to fully circulate through the body of an animal, it must pass through the chambers of the animal's heart twice.
Therefore, in birds and mammals, the blood is saturated with oxygen much better than that which flows in the body of lower animals. The highly oxygenated liquid makes it possible to noticeably increase metabolism and thus maintain a constant body temperature of the animal even in cold conditions. Because of this, birds and mammals are warm-blooded.
Organ structure in simple invertebrates
Simple invertebrates do not have a separate circulatory system. Nutrients inside the cell are transported todiffusion basis. In some simple organisms (for example, amoebae), food compounds are distributed in the body due to cytoplasmic movements that are observed during the movement of the animal. In those simple organisms that cannot move due to the rigid structure of the body, food particles spread through the rhythmic flow through the cytoplasm of their body.
The chambers use an absorbent cavity - for digestion, for digestion and for transporting nutrient particles throughout the body. These same particles from the absorbent cavity enter their cells as a result of diffusion and from there spread throughout the body. This transport further facilitates the movements of the animal.
Animals without a heart
Let's divide terrestrial invertebrates into two groups. The first of these includes organisms that are independent of water, but living in a humid environment. These are inhabitants of the soil, plants (for example, bark), living organisms (worms and parasites of the human body), wet stones and caves. During drought they die or undergo spore forms. Some of them are: flatworms, freshwater nematodes and oligochaetes such as earthworms and some leeches. Organisms belonging to the second group have become independent of water, reaching a fairly high activity (these are various insects and spiders).
In simple animals such as food worms, food enters the body through the mouth and is digested in the gastric cavity. All the work of the heart muscle is performed by the circulatory system, regulated by the vascular system and closely interconnected with the digestive system. Food particles enter the cells of the inner layers by diffusion. These layers penetrate into the middle layer with large intercellular spaces in which tissue fluid flows. Such a fluid transports nutrients to all cells, this transport is assisted by muscle contractions occurring in the body wall.
Among the invertebrates, there are species that have a closed circulatory system. An example would be worms. These animals have blood and blood vessels, but are not differentiated into veins and arteries. The entire circulatory system consists of two large vessels - abdominal and dorsal, the blood of which flows in opposite directions.
In the abdominal cavity - from front to back, and in the dorsal cavity - back. Smaller blood vessels that supply blood to the skin, intestines, and other parts of the body emerge from these large vessels. The flow of blood from the abdomen to the dorsal ventricle accommodates five pulsating vascular pairs in the anterior part of the body. Thanks to them, the circulatory system is closed.
Organ in molluscs and arthropods
In arthropods and mollusks, the primitive baggy development of the animal heart is already observed. Their circulatory system consists of blood vessels that transport blood from the heart to special fissures, from where it is distributed throughout the body. Bypassing all the tissues, the fluid returns to these vessels. And of them - in the heart. During the circulation of blood in the body, tissues and organs are supplied with oxygen and nutrients, and unnecessary and harmful substances are removed from them.
Conclusion
So, we looked at how the heart of various animals works. As you can see, this is a very responsible organ in any living organism. And not only for a person is the heart so important.
