HEART-STRUCTURE AND FUNCTIONS



Circulation and heart

The heart is a vital organ whose task is to pump blood throughout the body. Blood transfers oxygen and nutrients to the body and tissues for nutrition and functioning of the organs, and it transfers  away from organs substances that are unnecessary or harmful. Regarding the carbohydrates, the most important is glucose, which is the primary source of energy for the cells in the body. When oxygen is transferred to tissues and organs, blood ‘takes’ carbon dioxide  and transfers it to lungs, through which it is released into the environment. In the lungs, from the inhaled air, the blood takes oxygen and carries it to the tissue, thereby closing the circulation circle. Blood ‘travels’ through tubes built of muscular and connective tissue from the heart to the organs and from the organs back to the heart. The tubes that transfer blood from the heart to the organs are arteries, and those that return blood from the organs to the heart are veins. Blood ‘travels’ through arteries and veins thanks to heart pumping, which is a ‘drive motor’ for circulation (circulation = blood flow through the body).

The heart has atria and ventricles. The left and right atrium are the ‘lobby’ through which the blood passes before it enters the left or right chamber. The blood goes from the left atrium to the left ventricle, passing through the mitral valve, then from the left atrium to aorta, passing through the aortic valve. Aorta is the main and largest artery. It comes out directly from the heart, and all other arteries are branches of the aorta. They branch like a water supply network through a city, becoming increasingly branched and thinner. When the arteries are completely branched and reach a microscopic size they are called arteriole and pass into the capillaries, even smaller blood vessels. Through thin walls of capillaries in tissues and organs, blood transfers oxygen and nutrients to organs, and takes up waste matter and carbon dioxide. They are transferred by traveling from the capillaries to venules, these flow into veins,  larger as blood flows further, finally forming two large veins (superior and inferior, so called vena cava) that enter the right atrium. This is a major (or systemic) blood circulation.

From the right atrium  the blood, through the tricuspid valve, enters the right ventricle. The right ventricle pumps blood through the so-called pulmonary arteriy into the pulmonary circulation system. In the same way, these arteries branch to lung capillaries. Through their thin walls, the carbon dioxide is released from the blood in the lungs, and oxygen enters the blood from inhaled air. It is transported by blood that goes from the capillaries to the lung veins, and these flow into the left atrium. This is a small (pulmonary) blood circulation. From the left atrium the blood goes back to the left ventricle and the cycle continues.

Waste matter, products of metabolism in cells  are taken to the liver or to the kidneys (depending on certain properties of these substances), and through the liver, through the system of the bile and through the intestine, it is released out, while those through the kidneys are through  the urinal tract system released out by the urine.

As we can see, the role of blood is extremely important, and without the blood inflow, the organs, and therefore the organism, could not function. The driving force for blood flowing through the body is the heart as a pump, and blood flow pathways are integrated into the circulation system.

Heart – structure

The heart is a hollow muscular organ that has the task of pumping blood. The atria and ventricles, as well as the valves, have already been mentioned. The right and left sides of the heart are normally separated from each other by muscular tissue compartments and the blood from these two sides does mot mix. The blood passes from the left atrium into the left ventricle and into the aorta. On the other side, the blood from the right atrium passes into the right ventricle, then into the pulmonary artery and continues to the lungs. Atria are cavities in the upper part of the heart, having thin walls and serve as a lobby before blood enters into the ventricles. They also partially pump blood to the ventricles. Valves are slim membranous structures, which serve as a ‘door’ that allows blood to pass only in one direction. This ‘door’ must be fully opened when the blood is pumped forward, and then closed, not allowing the return of blood backwards. This opening and closing takes place at every heartbeat and tension of the valvular structures at opening and closing, along with some other phenomena, produces the well-known sound of heartbeats, which we can hear if we putan  ear on someone’s chest, or if we listen to the heart with a stethoscope (medical headphones ).

Between the left atrium and left ventricle there is a mitral valve. By opening it allows the blood to flow from the atrium to the ventricle, and by closing it prevents the return of blood from the left ventricle to the left atrium.

At the exit from the left ventricle there is an aortic valve. By opening it allows the blood to flow from the ventricle into the aorta, and by closing it prevents the return of blood from the aorta to the left ventricle.

Between the right atrium and the right ventricle there is a tricuspid valve. By opening it allows the blood to flow from the right atrium to the right ventricle, and by closing it prevents the return of blood from the right ventricle to the right atrium.

At the exit from the right ventricle is a pulmonary valve. By opening it allows blood to flow from the right ventricle into the pulmonary artery, and pby closing it prevents a return of blood from the pulmonary artery to the right ventricle.


About Heart Center BH

Copyright by BHSrce 2017. All rights reserved.