Studying the physiology of the cardiovascular system is very important for assessing the condition of any person. The heart, as well as the lymphatic and blood vessels, are directly related to this system. The circulatory system plays a key role in providing blood to the tissues and organs of the body. The heart, in fact, is a powerful biological pump. It is thanks to him that a stable and continuous movement of blood through the vascular system occurs. There are two circles of blood circulation in the human body.
Big circle
In the physiology of the cardiovascular system, an important role is played by a large circle of blood circulation. It originates from the aorta. The ventricle leaves to her left, ends with an increasing number of vessels, which as a result end up in the right atrium.
The aorta starts the work of all arteries in the human body - large, medium and small. Over time, arteries turn into arterioles, which, in turn, end with the smallest vessels - capillaries.
Capillaries with a huge network cover almost all organs and tissues of the human body. It is through them that blood transfers nutrients and oxygen itself to tissues. Back from them, various metabolic products penetrate into the blood. For example, carbon dioxide.
Briefly describing the physiology of the human cardiovascular system, it must be noted that capillaries end with venules. Of these, blood is sent to veins of various sizes. In the upper part of the human body, blood enters the upper vena cava, and in the lower, respectively, in the lower. Both the one and the other veins are connected in the atrium. Thus ends a large circle of blood circulation.
Small circle
The small circle in the physiology of the cardiovascular system is also important. It begins with the pulmonary trunk, which passes to the right ventricle, and then carries blood to the lungs. Moreover, venous blood flows through them.
The pulmonary trunk branches into two parts, one of which goes to the right, and the other to the left lung. And directly in the lungs, you can find pulmonary arteries, which are divided into very small ones, as well as arterioles and capillaries.
Flowing through the latter, the blood gets rid of carbon dioxide, and in return receives such necessary oxygen. Pulmonary capillaries end with venules, which ultimately form the veins of a person. Through the four main veins in the lungs, arterial blood gains access to the left atrium.
The structure and functions of the cardiovascular system, human physiology are described in detail in this article.
Heart
Speaking about the anatomy and physiology of the cardiovascular system, one should not forget that one of its key parts is the heart. This is an organ consisting almost entirely of muscle. Moreover, it is considered one of the most important in the human body. Using a vertical wall, it is divided into two halves. There is also a horizontal septum, which completes the division of the heart into four full cameras. This is the arrangement of the heart. The physiology of the human cardiovascular system is in many ways similar to many mammals.
The upper chambers of the heart are called the atria, and those located below are called the ventricles. The structure of the walls of the heart is interesting. They can be composed of three different layers. The innermost is called the "endocardium." He seems to line his heart from within. The middle layer is called "myocardium." It is based on the striated muscle. Finally, the outer surface of the heart is called the "epicardium", which is the serous membrane, which is the inner leaf for the pericardial sac or pericardium. The pericardium itself (or "cardiac shirt", as it is also called by experts) envelops the heart, providing its free movement. It is very similar to a bag.
Heart valves
In the structure and physiology of the cardiovascular system, do not forget about the valves of the heart. For example, between the left atrium and the left ventricle is only a bicuspid valve. At the same time, at the junction of the right ventricle and the corresponding atrium there is another valve, but already tricuspid.
There is also an aortic valve that separates it from the left ventricle and the valve of the pulmonary trunk.
When the atria contract, the blood from them begins to flow actively into the ventricles. And when, in turn, the ventricles contract, the blood is transmitted with great intensity to the aorta and the pulmonary trunk. During the relaxation of the atria, which is called “diastole,” the cavities of the heart are filled with blood.
For the normal physiology of the cardiovascular system, it is important that the valve apparatus work properly. After all, when the valves of the atria and ventricles are open, the blood coming from certain vessels as a result fills not only them, but also the ventricles, which need it. And during the atrial systole, the ventricles are completely filled with blood.
During these processes, the return of blood to the pulmonary and vena cava is completely excluded. This is because, due to contractions of the muscles of the atria, mouths of the veins are formed. And when the ventricular cavities are filled with blood, the valve flaps immediately close. Thus, there is a separation of the atrial cavity from the ventricles. There is a contraction of the papillary muscles of the ventricles just at the moment when the systoles become tense, they lose the opportunity to become turned towards the nearest atria. Moreover, during the completion of this process, the pressure in the ventricles increases, as a result, it becomes greater than in the aorta and even the pulmonary trunk. All these processes contribute to the opening of the valves of the aorta and pulmonary trunk. As a result, the blood from the ventricles is found in exactly those vessels in which it should be.
Ultimately, the importance of heart valves is difficult to underestimate. Their opening and closing are associated with changes in the final pressure in the cardiac cavities. The entire valve apparatus is responsible for ensuring the movement of blood in the cardiac cavities in one direction.
Properties of the heart muscle
Even describing very briefly the physiology of the cardiovascular system, it is necessary to talk about the properties of the heart muscle. She has three of them.
The first is excitability. The muscle of the heart is more excited than any other skeletal muscle. In this case, the reaction that the heart muscle is capable of is not always directly proportional to the external stimulus. It can be reduced as much as possible, responding to both small and powerful irritation.
Secondly, it is conductivity. The structure and physiology of the cardiovascular system are such that the excitation that propagates through the fibers of the heart muscle diverges at a slower rate than along the fibers of the skeletal muscle. For example, if the speed of the fibers of the muscles of the atria is about one meter per second, then the conductive system of the heart - from two to four and a half meters per second.
Thirdly, it is contractility. First, the muscles of the atria are contracted, after which comes the turn of the papillary muscles, and then the muscles of the ventricles. At the final stage, contraction occurs even in the inner layer of the ventricles. Thus, blood enters the aorta or pulmonary trunk. And more often there and there.
Also, some researchers refer to the physiology of the cardiovascular system as the ability of the heart muscle to work autonomously and increase the refractory period.
These physiological features can be discussed in more detail. The refractory period is very pronounced and elongated in the heart. It is characterized by a decrease in the possible excitability of the tissue during its maximum activity. When the refractory period is most pronounced, it lasts from one to three tenths of a second. At this time, the heart muscle does not have the ability to contract for too long. Therefore, in fact, the work is carried out on the principle of a single muscle contraction.
Surprisingly, even outside the human body, in some circumstances, the heart can work as autonomously as possible. Moreover, it is even able to maintain the correct rhythm. It follows from this that the cause of the contractions of the heart, when it is isolated, lies in itself. The heart can rhythmically contract under the influence of external impulses that arise in itself. This phenomenon is considered automatism.
Conductive system
In the physiology of the human cardiovascular system, a whole conducting system of the heart is distinguished. It includes working muscles, which are represented by the striated muscle, as well as special, or atypical, tissue. It is in her that excitement arises.
The atypical tissue of the human body consists of the sinus-atrial node, which is located on the posterior wall of the atrium, the atrioventricular node located in the wall of the right atrium, and the atrioventricular bundle, or the bundle of His. This bundle can pass through the septum and is divided at the end into two legs that go to the left and right ventricles, respectively.
Heart cycle
All heart work is divided into two phases. They are called systole and diastole. That is, contraction and relaxation, respectively.
In the atria, systole is much weaker and even shorter than in the ventricles. In the human heart, it lasts about one tenth of a second. But ventricular systole is a longer process. Its length can reach half a second. The total pause lasts about four tenths of a second. Thus, the entire cardiac cycle lasts from eight to nine tenths of a second.
Due to atrial systole, the active flow of blood into the ventricles is ensured. After that, the diastole phase begins in the atria. It continues throughout the systole of the ventricles. Just at this period, the atria are completely filled with blood. Without this, the stable operation of all human organs is impossible.
In order to determine what state a person is in, what is his state of health, heart performance is evaluated.
First you need to evaluate the stroke volume of the heart. It is also called systolic. So, it becomes known how much blood is sent by the ventricle of the heart to certain vessels. In a healthy adult of average configuration, the volume of such emissions is about 70-80 milliliters. As a result, when the ventricles contract, there are about 150 milliliters of blood in the arterial system.
It is also necessary to find out the so-called minute volume in order to assess a person’s condition. To do this, you need to find out how much blood is sent by the ventricle in one unit of time. As a rule, all this is evaluated in one minute. In a normal person, the minute volume should be from three to five liters per minute. Moreover, it can significantly increase with an increase in stroke volume and an increase in heart rate.
Functions
To thoroughly understand the anatomy and physiology of the cardiovascular system, it is important to evaluate its functions and understand them. Researchers distinguish two main and several additional.
So, in physiology, the functions of the cardiovascular system include transport and integrative. After all, the heart muscle is a kind of pump that helps blood circulate through a huge closed system. At the same time, blood flows reach the most remote corners of the human body, penetrate all tissues and organs, carry oxygen and various nutrients with them. It is these substances (they are also called substrates) that are necessary for the development and full functioning of body cells.
When the reverse outflow of blood occurs, it carries with it all the processed products, as well as harmful toxins and unwanted carbon dioxide. Only because of this, processed products do not accumulate in the body. Together, they are removed from the blood, in which they are helped by a special intercellular fluid.
Substances that are vital to the cells themselves pass through a large circle of blood circulation. So they do to the ultimate goal. At the same time, the pulmonary circulation is specifically responsible for the lungs and full oxygen metabolism. Thus, the two-way exchange between cells and blood is directly carried out in the capillaries. These are the smallest vessels in the human body. But at the same time, their importance should not be underestimated.
As a result, the transport function is divided into three stages. It is trophic (it is responsible for ensuring the uninterrupted supply of nutrients), respiratory (necessary for the timely delivery of oxygen), excretory (this is the process of taking carbon dioxide and products resulting from metabolic processes).
But the integrative function implies the reunion of all parts of the human body with the help of a single vascular system. The heart controls this process. In this case, it is the main body. That is why in case of even the smallest problems with the heart muscle or the detection of abnormalities in the functioning of the heart vessels, you should immediately consult a doctor. Indeed, in the long run this can seriously affect your health.
Considering briefly the physiology of the cardiovascular system, it is necessary to talk about its additional functions. These include regulatory or participation in all kinds of body processes.
The cardiovascular system discussed by us belongs to one of the main regulators of the body. Any change has an important effect on the general condition of a person. For example, when the volume of blood supply changes, the system begins to affect the volume of hormones and mediators delivered to the tissues and cells.
At the same time, do not forget that the heart is directly involved in a large number of global processes that occur in the body. This is inflammation, and the formation of metastases. Therefore, almost any disease to a greater or lesser extent affects the heart. Even ailments that are not directly related to cardiovascular activity, such as problems with the gastrointestinal tract or oncology, indirectly affect the heart. They can even negatively affect his work.
Therefore, it is always worth remembering that even minor disturbances in the functioning of the cardiovascular system can lead to serious problems. Therefore, they must be recognized in the early stages, using modern diagnostic methods. At the same time, the so-called percussion, or percussion, remains one of the most effective. It is interesting that congenital disorders can be determined in the first months of a baby’s life.
Age features of the heart
Age-related anatomy and physiology of the cardiovascular system is a special branch of knowledge. Indeed, over the years, the human body changes significantly. As a result, some processes slow down, more attention should be paid to their health, and especially to the heart.
It is interesting that the heart is quite strongly transformed throughout human life. From the very beginning of life, the atria is ahead of the growth of the ventricles, only by the age of two their development will stabilize. But after ten years, the ventricles begin to grow faster. The heart mass of a one-year-old baby already doubles, and by two and a half years - already three times. At the age of 15, a person’s heart weighs ten times more than a newborn’s.
Myocardium of the left ventricle also develops rapidly. When a child turns three years old, he weighs twice as much as the right myocardium. This ratio remains in the future.
At the beginning of the third dozen, the valves of the heart valves are compressed, and their edges become uneven. By senile age, atrophy of the papillary muscles inevitably occurs. Because of this, valve functions can be seriously impaired.
In adulthood and old age, the physiology and pathophysiology of the cardiovascular system are of greatest interest. This includes the study of the diseases themselves, pathological processes, as well as special pathologies that occur only with certain ailments.
Researchers of the heart and everything connected with it
This topic has repeatedly come under the scrutiny of doctors and major medical researchers. Indicative in this regard is the work of D. Morman "Physiology of the cardiovascular system," which he co-authored with his colleague L. Heller.
This is a profound academic study on the clinical physiology of the cardiovascular system, made by prominent American scientists. Its distinctive feature is the presence of several dozen bright and detailed drawings and diagrams, as well as a large number of tests for self-training.
It is noteworthy that this publication is intended not only for graduate students and students of medical universities, but also for practicing specialists, as they will find a lot of important and useful information for themselves in it. For example, this applies to clinicians or physiologists.
Books on the physiology of the cardiovascular system help build a complete picture of one of the key systems of the human body. Morman and Heller cover topics such as blood circulation and homeostasis, which characterize heart cells. They talk in detail about a cardiogram, problems of regulation of vascular tone, regulation of blood pressure, and dysfunctions of the heart. All this is a professional and accurate language that will be clear even to a novice doctor.
To know and study the anatomy and physiology of a person, the cardiovascular system is important to any specialist who respects himself. After all, as already noted in this article, almost every disease in one way or another is associated with the heart.