What are arteries and what is the arterial system?
Arteries are blood vessels that are responsible for carrying blood from the heart to all other organs and tissues within the human body (centripetal force). With exception of the pulmonary arteries, which carry deoxygenated blood and waste products, all other arteries generally carry oxygenated blood. The arterial walls are composed of three layers, arranged one over the other: the outmost layer known as tunica externa (connective tissue made up of collagen fibers), the connective tissue also known as tunica media (made of smooth muscles cells and elastic tissue), and the innermost layer, also known as tunica intima (mainly made of endothelial cells).
Depending on their diameter, arteries can be large, medium or small. If the diameter is less than 3 mm, they are called arterioles. Arterioles are small vessels that constitute the end portions of the artery’s branches and those which precede corresponding capillaries.
The arterial system is a part of the circulatory system, in reference to high pressure. The main structures that form the system include:
- Pulmonary arteries
- Systemic arteries
- Aorta
Pulmonary arteries
The pulmonary arteries are responsible for transporting deoxygenated blood and waste products from the heart to the lungs. Together with the pulmonary veins, they make up the pulmonary circulation (also called "heart-lung circulation" or "small circulation") or part of the circulatory system. Pulmonary circulation is a part of the cardiovascular system and is responsible for carrying deoxygenated blood and waste products from all the organs and tissues of the body away from the heart, to the lungs, and returning oxygenated blood back to the heart, as well as enriched nutrients to all other organs and tissues.
Systemic arteries
The systemic arteries are blood vessels that are responsible for transporting oxygenated blood and nutrients from the heart to all other organs and tissues within the body. The chest and abdomen, crossed from the aorta, receive blood directly from its many side branches, while the more peripheral parts of the body (head, neck, pelvis, upper and lower limbs) receive blood from the large arteries issued from the aorta itself (humeral artery, femoral artery, carotid artery, etc.)
The aorta
The aorta is the ultimate arterial vessel of the human body. It originates from the left ventricle of the heart, through an opening (regulated by the aortic valve), rises upward a short distance (known as “ascending aorta) and then sags back down to form the aortic arch (or systemic arch). It continues to form the descending aorta, which is composed of two portions, the thoracic aorta and the abdominal aorta, and then stops in front of the fourth lumbar vertebra, where it bifurcates into two common iliac arteries.
What functions do the arteries and the arterial system serve?
Arteries are responsible for carrying blood away from the heart and directing it toward all other tissues and organs of the body. The arterial system is extremely important in delivering oxygen and nutrients to all cells and tissues, as well as removing carbon dioxide and waste products. It also helps maintain the balance of proteins and ensures that the immune system is not compromised.
Severe complications such as myocardial infarction and stroke are known as the leading causes of death, as a direct result from a deteriorated arterial system.
