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18515789 blood circulation

18515789 blood circulation

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BLOOD CIRCULATION

General.

The blood system of vertebrates is a closed system, i.e. the blood vessels are not open -ended.

In the organs the arteries divide to form arterioles (small arteries) which in turn divide to form

numerous capillaries. The capillaries unite to form larger vessels, called the venules (small

veins). The venules leave the tissues and join with other venules to form veins. Veins leave the

organs and eventually join the venae cavae. It is thus clear that the arterial and venous blood

link up by means of capillaries in the tissues.

In this section we will discuss the main circulatory system.

Pulmonary Circulation.

The pulmonary artery arises from the right ventricle and tranports deoxygenated blood

(oxygen-poor) to the lungs, where the blood becomes oxygenated again. The four pulmonary

veins return the oxygenated blood (oxygen-rich) to the left atrium of the heart. The pulmonary

circulation is also referred to as the lesser circulation. The summary of the pulmonary

circulation is thus:

Right Ventricle - pulmonary artery - lungs - pulmonary veins - left atrium - left ventricle.

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Pulmonary and Systemic Circulation

Systemic Circulation.

Oxygenated blood is pumped from the left ventricle into the aorta. Branches of the aorta convey

blood to all the tissues and organs of the body (except the lungs). The tissue cells are

oxygenated and deoxygenated blood returned to the heart via the superior and inferior

venae cavae. The blood then flows via the tricuspid valve into the right ventricle, from where it

joins the pulmonary circulation. The systemic circulation is also referred to as the greater

circulation. The summary of the systemic circulation is thus:

Left ventricle - aorta - organs - venae cavae - right atrium - left ventricle.

The Hepatic Portal System of Circulation.

This system serves the intestines, spleen, pancreas and gall bladder. The liver receives it

blood from two main sources. The main sources are the hepatic artery, which as a branch of the

aorta, supplies oxygenated blood to the liver and the hepatic portal vein, which is formed by the

union of veins from the spleen, the stomach, pancreas, duodenum and the colon. The hepatic

portal vein transports, inter alia, the following blood to the liver:

• absorbed nutrients from the duodenum;

• white blood cells (added to the circulation) from the spleen;

• poisomous substances, such as alcohol which are absorbed in the intestines, and

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BLOOD CIRCULATION | General| Pulmonary Circulation| Systematic Circulation| Hepatic Portal System Circulation| Coronary Circulation | General. The blood system of vertebrates is a closed system, i.e. the blood vessels are not open -ended. In the organs the arteries divide to form arterioles (small arteries) which in turn divide to form numerous capillaries. The capillaries unite to form larger vessels, called the venules (small veins). The venules leave the tissues and join with other venules to form veins. Veins leave the organs and eventually join the venae cavae. It is thus clear that the arterial and venous blood link up by means of capillaries in the tissues. In this section we will discuss the main circulatory system. Pulmonary Circulation. The pulmonary artery arises from the right ventricle and tranports deoxygenated blood (oxygen-poor) to the lungs, where the blood becomes oxygenated again. The four pulmonary veins return the oxygenated blood (oxygen-rich) to the left atrium of the heart. The pulmonary circulation is also referred to as the lesser circulation. The summary of the pulmonary circulation is thus: Right Ventricle - pulmonary artery - lungs - pulmonary veins - left atrium - left ventricle. Pulmonary and Systemic Circulation Systemic Circulation. Oxygenated blood is pumped from the left ventricle into the aorta. Branches of the aorta convey blood to all the tissues and organs of the body (except the lungs). The tissue cells are oxygenated and deoxygenat ...
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