There is no need to explain that the heart, even in the animal’s body, is the strongest muscle. And, of course, no animal can exist without it. There are some exceptions, though. This organ is different from the human, because it is "modified by nature."
The human heart is at the highest stage of development. Thanks to the system of valves and pacemakers, it is an effective pump that supplies the whole body with blood. Due to the circulation of blood in the veins and arteries, the body receives nutrients obtained from food during digestion and effective gas exchange.
In an animal
If the blood does not reach the organ within a few minutes, irreversible changes in the tissues and their death due to failure of functioning occur in this place. Therefore, the heart of the animal constantly beats. The rhythm of an organ consists of consecutive spasms of the body. The tone of strokes corresponds to contractions of the cardiac cavities and their diastole.
Structure
As mentioned earlier, the heart structure of animals is a cone-shaped muscle. With the base basis cordis and apex apex cordis facing cranio-ventrally. In animals, the heart is four-chamber 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. Ears bulge a little. Scallop-like muscles are located in them, which, when reduced, contribute to the expulsion of blood. The remaining area is occupied by 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
An aorta emerges from the left ventriculum; it is divided at the base into a brachiocephalic trunk and a thoracic aorta.
The brachiocephalic trunk supplies the anterior 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 enters the middle sacral artery. But this does not end her path, she falls into the tail of the animal.
The structure of the right ventricle of the heart in mammals
An artery enters the lungs from the right ventricle. Then it is divided into two parts (trunk) leading to the right side of the lung and the left side of the lung.
Circulatory system
According to the laws of the course of blood vessels, there are those that remove blood in the heart. And those that bring.
The circulatory system is one of many systems in the body necessary for the proper functioning and functioning 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 unnecessary metabolic products (toxins). These functions are identical for vertebrate and invertebrate animals. And the existing differences in the structure of this system between groups developed during evolution.
Organ in Pets
The heart of pets is four-chamber. And blood circulation occurs through contractions of the valvular apparatus of the heart. Blood flows in one direction. And the walls of the heart consist of:
- the inner layer of the endocardium;
- the middle layer of the myocardium;
- the outer layer of the epicardium.
Blood circulation and organ structure in vertebrates
The heart of vertebrate animals and the circulatory system consists of the same elements, that is, the heart, veins, arteries, aorta and blood vessels. Differences in the structure of the circulatory system that occurred during evolution are observed. Basically, they relate to the structure of the organ, and were associated with a displacement of the pulmonary system.
Blood circulation and heart features in the simplest vertebrates
Consider how the heart of chordate animals is arranged. In the simplest vertebrates - fish - it consists of four chambers: the arterial cone, ventricle, vestibule and venous esophagus. Blood flows from the arterial cone to the aorta. And then to the gills, where it is saturated with oxygen. Then, passing through the abdominal aorta, it delivers blood to all tissues. In contrast, blood from 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, and has an exit to the left lobby. Ventricular contraction causes non-oxygenated blood to be pushed from the right atrium into the aorta and, therefore, into many small pulmonary arteries. The oxidized blood in the right atrium enters the ventricles of the heart of animals.
And leaves him at the end of the cut. 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 blood circulation around the body. This is due to the phenomenon of mixing oxygenated and deoxidized blood in the heart chamber.
Amphibians
In reptiles and amphibians, the heart in the arterial cone and chamber has a special septum. With the disappearance of the gills in the venous amphibians and arteries of the gill arches, evolution created a combination of the dorsal and abdominal aorta. These compounds are called arches of the aorta and the entire blood circulation - a large path of blood circulation that occurs in fish. In connection with the acquisition of lungs in the respiratory function of these animals, a second blood circulation developed. Called pulmonary or small.
The imperfection of the circulatory system of amphibians is the mixing of blood in the chamber. Blood flowing from the lungs is not sufficiently saturated with oxygen. It mixes with the one that flows through the tissue. And leaves too much oxygen there. It also mixes with blood flowing through blood vessels in the skin, acquiring a certain amount of oxygen there. Due to the difficulties caused by mixing oxygenated blood with the non-oxygen evolution of the circulatory system, she moved to the separation of venous blood from arterial pathways.
Reptile features
The heart of an animal of this kind has a partition in the chamber, but it is incomplete. A complete partition separating the right and left chambers is located in the heart of birds and mammals. In animals of these groups, blood does not completely mix. The arterial cone is reduced and forms only the base of the aorta and pulmonary arteries. In order for blood to circulate completely through the body of the animal, it must pass twice through the chambers of the heart in animals.
Therefore, in birds and mammals, the blood is saturated with oxygen much better than the one that flows in the body of lower animals. Highly oxygenated liquid allows you to significantly increase metabolism and, thus, maintain a constant body temperature of the animal, even in cold conditions. Due to this, birds and mammals are warm-blooded.
Organ structure in simple invertebrates
Simple invertebrate organisms do not have a separate circulatory system. The nutrients within the cell are carried through diffusion. In some simple organisms (for example, amoeba), food compounds are distributed in the body due to the 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 propagate through the rhythmic flow through the cytoplasm of their body.
The cells use an absorbent cavity - for cleavage, 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 movement of the animal.
Animals without a heart
Divide terrestrial invertebrates into two groups. The first of them includes organisms that are independent of water, but living in a humid environment. These are inhabitants of soil, plants (for example, bark) of living organisms (worms and parasites of the human body), wet stones and caves. During a drought, they die or undergo spore forms. Here are some of them: flatworms, freshwater nematodes and oligochaetes, such as earthworms and some leeches. Organisms belonging to the second group became independent of water, reaching quite 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. Particles of food enter the cells of the inner layers by diffusion. These layers penetrate the middle layer with large intercellular spaces in which tissue fluid flows. Such a fluid transports nutrients to all cells, and muscle contractions in the body wall help this transport.
Among invertebrates, there are species that have a closed circulatory system. An example would be worms. These animals have blood and blood vessels, however undifferentiated into veins and arteries. The whole circulatory system consists of two large vessels - the abdominal and dorsal, whose blood flows in opposite directions.
In the abdominal cavity - from front to back, and in the dorsal - back. Smaller blood vessels supplying blood to the skin, intestines, and other parts of the body exit these large vessels. The flow of blood from the abdominal cavity into the dorsal ventricle allows you to place five pulsating vascular pairs in the front of the body. Thanks to them, the circulatory system is closed.
Organ in mollusks and arthropods
In arthropods and mollusks, a primitive baggy development of the heart of animals is already observed. Their circulatory system consists of blood vessels that transport blood from the heart to particular fissures, from where it is distributed throughout the body. Bypassing all tissues, the fluid returns to these vessels. And of these, in the heart. During blood circulation in the body, tissues and organs are supplied with oxygen and nutrients, and unnecessary and harmful substances are removed from them.
Conclusion
So, we examined how the heart of various animals is arranged . 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.