In our article we will consider the circulatory system of mammals, its components and features of functioning. For all living organisms, it is essential. This is the implementation of gas exchange, transport of nutrients, the formation of immunity and maintaining homeostasis. Thanks to what features are such complex functions possible?
Who are mammals?
Mammals have a number of systematic features. First of all, it is feeding the young with milk, which is secreted by the specialized glands of the females. All mammals have limbs that are located under the body, and a hairline that periodically changes during molting. The skin of these animals contains not only mammary, but also sweat, sebaceous and odorous glands. Mammals are extremely warm-blooded organisms, which is provided by the features of the circulatory system.
The structure of the circulatory system of mammals
The most progressive structural features of the circulatory system among vertebrates are representatives of the Mammals class. It includes a four-chamber heart and a closed vascular system. Blood is able to perform its functions due to continuous movement. Therefore, the organs that form the circulatory system in mammals are mainly formed by muscle tissue. And the heart is no exception.
This is a hollow muscular organ consisting of four chambers: two atria and ventricles. These departments are separated by complete partitions and communicate via valves. For this reason, venous and arterial blood never mix, which, together with the perfect mechanisms of thermoregulation, determines the warm-bloodedness of mammals.
What is warm-bloodedness?
Warm-blooded animals are animals whose body temperature does not depend on the environment. This group includes birds and mammals, including humans. Why do other animals not have this progressive trait? It's all about the structure of the heart. Consider this issue by comparing representatives of different systematic units. Thus, the circulatory system of mammals and reptiles has significant differences. The heart of the latter consists of three chambers, between which there is an incomplete partition. It only partially prevents the mixing of venous and arterial blood. Therefore, all reptiles are cold-blooded and are forced to survive the wintering period at the bottom of reservoirs, in soil and other shelters.
Two circles of blood circulation
The circulatory system of mammals is also formed by blood vessels. Blood flows through them. Arteries emerge from the heart, the largest of which is called the aorta. Then they branch and pass into the capillaries. These are the smallest vessels. The capillary network is collected in venules. Gradually they increase in diameter. This is how veins are formed that carry blood to the heart.
The circulatory system of mammals forms two circles of blood circulation. Small passes only through the lungs. It begins in the right ventricle and carries blood through the arteries, capillaries and veins of this organ to the left atrium. As a result, oxygen from the air contained in the lungs passes into the blood, and carbon dioxide - in the opposite direction. The large circle of blood circulation begins in the left ventricle and, passing through the vessels of all organs of the body, carries blood to the right atrium.
Blood composition
The mammalian circulatory system would not be able to carry out its functions without the special fluid tissue that circulates through the vascular system. It is called blood. The basis of this tissue is the intercellular substance - plasma. In it there are shaped elements of three types, each of which performs its functions. Plasma transfers from the tissues to the organs of excretion the final metabolic products, excess fluid and salts. Since the basis of blood is water with a high heat capacity, it maintains a stable body temperature in mammals.
Red blood cells carry out gas exchange, transporting oxygen and carbon dioxide. These cells also cause red blood because they contain iron. White blood cells form the immunity of organisms. They intracellularly digest foreign particles by phagocytosis. Platelets provide a blood coagulation process. This is a complex chemical process of turning proteins into an insoluble form. Thanks to this, the body is protected from blood loss. But the implementation of all these vital functions is possible only with the combined activity of these cells, heart and blood vessels.
Features of the respiratory system
The mammalian circulatory system is anatomically and functionally associated with the respiratory system. The latter is represented in mammals by the airways and lungs. The first consists of a series-connected nasal cavity, nasopharynx, larynx, trachea and two bronchi. They are covered with lungs, which contain a large number of tiny vesicles - alveoli, braided by a dense network of capillary vessels. It is in the alveoli that gas exchange occurs. Mammal respiration is a complex process. Its implementation involves intercostal muscles, the walls of the abdominal cavity and the diaphragm.
The relationship of the circulatory and respiratory systems of mammals
The circulatory and respiratory systems of mammals are closely interconnected. When inhaling, oxygen enters the alveoli of the lungs through the respiratory tract. From here it penetrates the capillaries. Entering the blood, red blood cells attach oxygen. Instead of nuclei, these cells contain a special substance called hemoglobin. It consists of protein and an iron-containing compound - heme. This chemical element forms an unstable compound with oxygen. With blood flow, red blood cells carry it throughout the body. Giving up oxygen, they attach carbon dioxide, which again enters the lungs. With expiration, this metabolic product is removed from the body.
So, the circulatory system of mammals forms the heart and blood vessels. It has a closed type. The progressive features of the structure of this system is the presence of four chambers of the heart and a complete partition between them. This makes mammals warm-blooded. The respiratory system is anatomically and functionally related to the circulatory system. It consists of airways and lungs. It is only thanks to the coordinated activity of these systems that mammals breathe at the cellular, tissue and organism levels.