Body circulation
definition
The body's circulation describes the system in which blood is pumped from the heart into the body and then comes back here.
Opposite this is the pulmonary circulation, too small cycle called, in which the oxygen-poor blood is transported from the heart to the lungs, here is enriched with oxygen and flows back to the heart.
Structure of the body circulation
The circulatory system includes the heart and all the vessels through which blood flows through the body.
The body's circulation begins in the heart, namely in the left ventricle. From this the blood is expelled into the main artery (aorta). The aorta runs from the heart in a gentle arc downwards completely through the entire trunk. Numerous other arteries branch off from the aorta. From these, in turn, further arteries branch off, which further divide into arterioles and ultimately into capillaries.
Capillaries are the smallest vessels in the body's circulation. This is where the exchange of oxygen and nutrients takes place in return for metabolic end products such as carbon dioxide between the blood and the correspondingly supplied organ.
Illustration of the blood circulation
Human blood circulation
A - pulmonary circulation
(small cycle)
Right HK> Lung>
Left HK
B - body circulation
(big cycle)
Left HK> Aorta> Body
red - oxygenated blood
blue - deoxygenated blood
- Neck-head-vein -
Brachiocephalic vein - Superior vena cava -
Superior vena cava - Right atrial -
Atrium dextrum - Right ventricle -
Ventriculus dexter - Right lung -
Pulmodexter - Lower vena cava -
Inferior vena cava - Common pelvic vein -
Vena illiaca commonis - Clavicle artery -
Subclavian artery - Aortic arch - Arcus aortae
- Left atrium -
Atrium sinistrum - Left ventricle -
Ventriculus sinister - Left lung -
Pulmo sinister - Abdominal aorta -
Abdominal aorta - Femoral artery -
Femoral artery
HK = ventricle
You can find an overview of all Dr-Gumpert images at: medical illustrations
The aorta ends in the Pelvic area in the two big ones Pelvic arteries (Common iliac arteries) on. From these two pelvic arteries, in turn, further arteries, arterioles and capillaries branch off, which are used to supply the lower extremities, i.e. the legs and Feet, are responsible.
At the exit point of the aorta from the left ventricle, the aorta describes an arc, the so-called Arcus aortae. Among other things, important arteries originate from this arch, which are used for the supply of the upper extremity (arms and legs) and the head can be further divided into arteries, arterioles and capillaries.
So that the blood can flow back to the heart after the supply of organs and other structures, the capillaries open into Venules. These venules then combine to form larger ones Veins. These veins ultimately all flow into the large vena cava (Vena cava).
This large vena cava can be divided into two areas, the superior and inferior vena cava. The lower great vena cava (Inferior vena cava) arises from the confluence of the two large veins from the lumbar region (Common iliac veins) and takes numerous other veins from the pelvic and abdominal area, thus all blood from the area below the Diaphragm on.
The superior great vena cava (Superior vena cava) is responsible for the area above the diaphragm. It thus contains the blood that Arms and head flows back to the heart and arises from the confluence of the two larger vessels, the right and left Brachiocephalic vein.
Both large vena cava flow into the from below or above right atrium of the heart.
The heart
The heart is a muscular hollow organ and represents the center of the body's circulation. It ensures that the blood is expelled into the main artery and is therefore pumped through the entire body.
The heart consists of the left and right atria and the left and right ventricles.
The blood is expelled into the main artery from the left ventricle, the muscularly stronger chamber.
When the blood returns to the heart from the circulatory system, the blood first flows into the right atrium. From here the blood flows into the right ventricle. The blood flows from the right ventricle via the small circulation, the pulmonary circulation, to the lungs, where it is enriched with oxygen.
When the blood returns from the lungs to the heart, it first flows into the left atrium and from there into the left ventricle.
Here then the body cycle begins again.
Vessels
The vessels make up the main part of the body's circulation. A distinction is made between vessels that flow away from the heart and thus bring blood to the organs, and vessels that flow back to the heart and thus bring the blood back to the heart and thus also to the lungs for oxygenation.
The vessels that flow away from the heart (they are usually drawn in red for oxygen-rich blood) are the aorta, arteries, and arterioles. Usually the capillaries are also included.
The vessels that lead back to the heart are the venules and veins. These are usually shown in blue for low-oxygen blood.
physiology
There are various components that support a functioning body circulation.
First, this is the Striking strength of the heart. Because the heart contract, so the muscle tissue of the heart can contract, with each heartbeat sufficient blood volume is drawn into the aorta given and that blood in the Vessels pumped on. This process can be seen as a pulse in various places, for example on the wrist Radial arteries and ulnaris also keys.
Next must be the Elasticity of the vessels be secured. This elasticity means that the vessels move with the volume of blood Passively expand and contract again. This is especially for that Air vessel function important to the aorta.
The Windkessel function describes the phenomenon that after a heartbeat blood enters the aorta is pumped. This causes the aorta to expand to accommodate the ejected blood. Once the heart relaxes, the aorta also relaxes and the blood reservoir is driven further away from the heart. This also compensates for the strong pressure difference that exists between Systole (Tension and expectoration of the heart) and diastole (Relaxation and filling phase of the heart) arises between the heart and aorta.
Elasticity is just as important in all other vessels of the human body. These too must be able to expand or contract. So this can for example adapt to external conditions. This includes that vessels themselves narrow if there is insufficient volume in order not to let the lower blood volume sink into the periphery, for example in the leg vessels.
The pulmonary circulation
The pulmonary circulation is also known as the small body circulation. Its main function is to enrich the blood with oxygen (O2) and to release harmful carbon dioxide (CO2).
The pulmonary circulation begins in the right atrium of the heart (atrium dextrum), which leads via the tricuspid valve (valva atrioventricularis dextra) into the right ventricle (ventriculus dexter). The venous blood, which comes from the periphery of the body, is pumped through the pulmonary arteries (arteria pulmonalis) into the two lungs. Gas is exchanged in the capillaries by enriching the blood with oxygen (O2) and at the same time releasing carbon dioxide (CO2). The now arterial blood is transported to the left atrium via four pulmonary veins (pulmonary veins), from where it enters the left main chamber. This is where the great body circulation follows, which supplies the entire body with oxygen-rich blood.
What is the difference between the large and small circuit?
The small and large body circuits both carry blood within our body, but they have different functions.
The great body circulation begins in the left ventricle (ventriculus sinister). Arterial blood, which is enriched with oxygen (O2), is pumped into the body via the aorta. This blood supplies the most diverse areas, such as our organs, our brain and all muscles. For this reason, there is high pressure (approx. 120mmHg) in the great body circulation, as the blood has to overcome a long distance. The used venous blood now contains little oxygen and a lot of carbon dioxide (CO2).
It is returned to the right heart via the upper and lower vena cava (vena cava superior / inferior), where the small circulation (also called pulmonary circulation) connects. Starting from the right atrium (atrium dexter) via the right ventricle (ventriculus dexter) the blood reaches the lungs, where the gas exchange takes place. This is where carbon dioxide is released and oxygen is absorbed, so that arterial blood returns to the left heart via the pulmonary veins. From here the great body cycle begins again. In the pulmonary circulation it is not about the supply of the tissue with oxygen, but purely about the gas exchange, so that low pressures (approx. 15mmHg) are sufficient here.
Summary
The body cycle describes the system that ensures that all parts and organs of the body are supplied with sufficient blood and thus with nutrients and oxygen. Relevant diseases that disrupt a well-functioning body circulation are all pathologies that reduce the function of the vessels or the heart. For example, a calcification and thus narrowing of arteries (Arterial stenosis) or a reduced work performance of the heart (Heart failure) make it difficult for the body to function properly.
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