How blood circulates in the body, and how blood circulates in the body

Blood always flows in a certain direction along a certain tube in the human body, which is called blood circulation, and this set of circulatory pipes composed of heart and blood vessels is called blood circulatory system. It is the "inland waterway network" that maintains the human life activities of the municipalities directly under the central government.

People eat, drink, breathe, the nutrients in the food are mainly absorbed in the small intestine, oxygen to the lungs, it is the blood circulation that sends them to the billions of cells throughout the body, where they are further transformed into the necessary pastoral energy for life activities. At the same time, the blood circulation timely transports the carbon dioxide and waste products produced during the activities of various tissues and organs of the body to the lungs, kidneys and **, and excretes them from the body.

The entire blood circulation is made up of three parts.

The blood containing a large amount of oxygen in the left ventricle flows through the aorta, middle artery, arterioles, and branches into the capillaries of the whole body, and the nutrients and oxygen are handed over to the tissues, and after the waste and carbon dioxide are recovered, it returns to the right atrium and right ventricle through the venules, middle veins, and large veins. This circulation passes through the whole body, so it is called "systemic circulation".

From here, carbon dioxide-filled blood returning to the right ventricle travels through the pulmonary arteries in the capillaries of the lungs to release carbon dioxide to absorb fresh oxygen, and then returns to the left atrium and left ventricle through the pulmonary veins. This circulation is called the "pulmonary circulation", also known as the "small circulation". It only takes 20 to 25 seconds for blood to circulate in the large circulation, and 4 to 5 seconds to circulate in the small circulation.

The circulation of blood in the capillaries is called "microcirculation". Because the capillaries are the "destination" to complete the transportation task, it is also called "peripheral circulation leather". There are 100 billion to 160 billion capillaries in the human body.

These capillaries play an important role in health by ensuring that the cells in the body live in an environment that is neither dry nor waterlogged, neither too acidic nor too alkaline, and has proper nutrition.

Blood circulation not only transports nutrients, oxygen, carbon dioxide and waste products, but also carries various hormones throughout the body. Hormones are signaling molecules, and various cells receive different signals from the blood, knowing what they should do now and how they are doing, so that the activities of the whole body can work well together.

According to the different circulatory pathways, it is divided into systemic circulation and pulmonary circulation. The two cycles run at the same time and communicate with each other.

Systemic circulation (large circulation): When the ventricle contracts, blood is shot into the aorta from the left ventricle, and then through the branches of the aorta at all levels to the capillaries of the whole body, where the blood exchanges substances with surrounding tissues and cells, and then through the veins at all levels, and finally returns to the right atrium through the superior and inferior vena cava and coronary sinus. The main function of systemic circulation is to nourish all organs, tissues and cells of the whole body with high oxygen content and nutrient-rich blood, and to transport metabolites back to the heart.

After circulation, the blood turns from bright red to dark red.

The right atrium flows back to the right ventricle.

Pulmonary circulation (small circulation): Blood is ejected from the right ventricle, through the pulmonary trunk and its branches to the alveolar capillaries, where gas exchange takes place, and then enters the left atrium through the pulmonary veins. The pulmonary circulation is characterized by a short flow of blood and its main function is to oxygenate the blood and excrete carbon dioxide.

The left atrium flows back into the left ventricle.

1. Large circulation (systemic circulation): left ventricle - aorta - middle artery - arteriole - arteriole - capillary artery - (material exchange) - capillary vein - venule - venule - middle vein - superior and inferior vena cava - right atrium.

2. Small circulation (pulmonary circulation): right ventricle - pulmonary artery - middle artery - arteriole - arteriole - pulmonary capillary artery - (gas exchange) - capillary static potato pulse - venules - venules - venules - middle vein - pulmonary vein - left atrium.

The main significance of blood circulation is to ensure the body's metabolism. The tissues of the animal body obtain various nutrients, water and oxygen from the blood, and use these substances for oxidation to produce heat energy and ensure normal function.

There are only two ways for blood circulation in the human body: systemic circulation and pulmonary circulation. The blood ruler rubber contains the blood from the left ventricle into the aorta, and then flows through the arteries, capillary networks, and veins throughout the body, and finally collects into the superior and inferior vena cava, such as the circulation that flows back to the right atrium, which is called systemic circulation.

In the systemic circulation, blood flows through the capillary network, which not only sends nutrients to the cells, but also takes away the waste products produced by the cells; And the hemoglobin in red blood cells releases the oxygen it binds to for the cells to use.

The blood coming back from the vein enters the right atrium through the tricuspid valve to the right ventricle, the right ventricle exits the parapulmonary vein to exchange oxygen in the lungs, enters the pulmonary artery into the left ventricle, passes through the mitral valve sub-left ventricle, and the left arm accompanies the ventricle to the round rubber artery arch into the whole body, the cardiopulmonary circulation is a small circulation, and the circulation between the heart and the whole body is a large circulation.

Systemic circulation: left ventricle - aorta - arteries at all levels - capillaries throughout the body - veins at all levels - superior and inferior vena cava - right atrium (blood enters the aorta from the left ventricle, and then flows through the arteries at all levels, capillary networks, and veins at all levels throughout the body, and finally collects into the superior and inferior vena cava, and flows back to the right atrium.) This circulatory pathway is called the systemic circulation.

In the systemic circulation, when the blood flows through the capillary network around the tissues and cells of various parts of the body, not only the nutrients transported are sent to the cells, and the carbon dioxide and other waste products produced by the cells are taken away, but the hemoglobin in the red blood cells releases the oxygen it binds for the cells to use. In this way, the blood changes from oxygen-rich, brightly red arterial blood to less oxygen-rich, dark red venous blood. ）

Pulmonary circulation: right ventricle - pulmonary artery - pulmonary capillaries - pulmonary vein - left atrium (blood flowing back to the right atrium is pressed into the pulmonary artery through the right ventricle, flows through the capillary network of the lungs, and then flows back to the left atrium from the pulmonary vein, this circulation pathway is called pulmonary circulation.) As blood flows through the capillary network of the lungs, carbon dioxide from the blood enters the alveoli, and oxygen from the alveoli enters the bloodstream, where it binds to hemoglobin in red blood cells.

In this way, the blood changes from venous blood with less oxygen and dark red color to oxygen-rich arterial blood with bright red color. ）

Systemic circulation is the blood from the left side of the heart to the right side, and pulmonary circulation is the blood from the right side of the heart back to the left, thus forming a complete blood circulation pathway.