Veins, Arteries and Capillaries Functions

Veins, Arteries and Capillaries Functions

In General, it should be understood that blood circulation in the body is carried out through the arteries, capillaries and veins. We will tell you more about the functions of each of them in this article.

Functions of Arteries in Human Body

Arteries type part of the circulatory system. They carry blood that is oxygenated after it has been pumped from the heart. Coronary arteries likewise assist the heart in pumping blood by sending out oxygenated blood to the heart, enabling the muscles to function. Arteries carry oxygenated blood away from the heart to the tissues, except for pulmonary arteries, which carry blood to the lungs for oxygenation (generally veins carry deoxygenated blood to the heart however the pulmonary veins carry oxygenated blood also). There are two types of unique arteries. The pulmonary artery carries blood from the heart to the lungs, where it receives oxygen. It is special because the blood in it is not “oxygenated”, as it has not yet gone through the lungs. The other unique artery is the umbilical artery, which carries deoxygenated blood from a fetus to its mother.

Arteries have a blood pressure higher than other parts of the circulatory system. The pressure in arteries differs during the cardiac cycle. It is greatest when the heart contracts and lowest when heart unwinds. The variation in pressure produces a pulse, which can be felt in various areas of the body, such as the radial pulse. Arterioles have the greatest cumulative impact on both local blood circulation and on general blood pressure. They are the primary “adjustable nozzles” in the blood system, throughout which the best pressure drop happens. The combination of heart output (cardiac output) and systemic vascular resistance, which refers to the collective resistance of all of the body’s arterioles, are the principal factors of arterial blood pressure at any given minute.

Functions of Capillaries

The capillaries are accountable for facilitating the transportation and exchange of gases, fluids, and nutrients in the body. While the arteries and arterioles act to transfer these products to the capillaries, it is at the level of capillaries where the exchange happens.

The capillaries also work to receive carbon dioxide and waste items that are then delivered to the kidneys and liver (for wastes) and the lungs (for exhalation of co2).

In the lungs, oxygen diffuses from the alveoli into capillaries to be attached to hemoglobin and be brought throughout the body. Co2 (from deoxygenated blood) in turn flows from the capillaries back into alveoli to be exhaled into the environment.

Also, fluids and nutrients diffuse through selectively permeable capillaries into the tissues of the body, and waste items are picked up in the capillaries to be transported through veins to the kidneys and liver where they are therefore processed and removed from the body.

Functions of Veins

After the capillaries release oxygen and other compounds from blood into body tissues, they feed the blood back towards the veins. First the blood gets in microscopic vein branches called venules. The venules carry out the blood into the veins, which carry it back to the heart through the venae cavae. Vein walls are thinner and less elastic than artery walls. The pressure pushing blood through them is less. In fact, there are valves within the lumen of veins to prevent the backflow of blood.

Veins can differ considerably in size. The largest vein in the body is called the vena cava, which is Latin for ‘hollow vein.’ There are two areas of the vena cava, one below the heart and one above it. The area above the heart is called the superior vena cava, and it returns blood from the head, neck, chest, and upper limbs back to the heart. You can remember this term by associating the word ‘exceptional’ with ‘above.’

The lower section is called the inferior vena cava, and it returns blood from all other parts of the body back to the heart. Similar to the aforementioned example, ‘inferior’ can be related to ‘below.’ As we get farther away from the heart and toward extremities, veins branch out and get smaller sized and smaller. The tiniest veins are called venules.


If you buy something through a link on this page, we may earn a small commission.

/// About Reyus Mammadli (article's author)

Health and Welfare
Add a comment