Arteries: Definition, Structure, Types, Functions, Diseases

Arteries are the elastic, muscular tubes (blood vessels) responsible for carrying the blood away from the heart and distributing it to several other organs and tissues. Simply, the blood vessels that carry blood away from the heart are arteries.

  • All arteries carry the oxygenated blood except the pulmonary arteries, which carry the deoxygenated blood from the right ventricle to the lungs for purification, and the umbilical arteries, which supply deoxygenated blood to the placenta from the fetus. 
  • Arteries carry the blood at a high pressure, of about 120 mm of Hg; hence they are thick, muscular, and robust in nature to sustain the pressure and do not need valves to check the backflow of the blood. Hence, they are valveless thick-walled blood vessels.
  • Artery arises from the left ventricle of the heart as a single main and largest artery called the aorta. The aorta is divided into four sections – ascending aorta, aortic arch, thoracic aorta, and abdominal aorta. From each section, different arteries, called the major arteries arise. These major arteries branch repeatedly to form a network of systemic arteries that supply blood to all organs and tissues of the body. The arteries become finer and finer as they branch out, and finally become arterioles; the finer arteries that supply to tissues. These arterioles further become smaller and are connected to capillaries to supply blood to every cell of the body. 

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Structure of Arteries

Arteries are thick-walled, muscular, and valveless blood vessels. Anatomically, the wall of the artery is made of three layers, the tunica externa, the tunica media, and the tunica intima

  1. Tunica Externa

It is the outermost layer of arteries, also known as tunica adventitia. It is primarily composed of connective tissue made of collagens and elastic tissues.

 This layer attaches arteries to the surrounding tissues and provides structural support. This layer sustains the blood pressure and checks overexpansion of the arteries.

Structure of Arteries
Structure of Arteries
  1. Tunica Media

It is the middle layer primarily composed of smooth muscle fibers arranged circularly. It also contains some amount of collagen and elastic tissues.

In smaller arteries and arterioles, smooth muscle cells are abundant; whereas, in larger arteries and aorta, collagen and elastic tissues are in considerable amounts. 

Tunica media functions to control the diameter of arteries; hence regulating the blood pressure and the blood flow.  

  1. Tunica Intima 

It is the thinnest and the innermost layer of the arterial wall. It is primarily composed of smooth endothelial cells. A single-layer simple squamous epithelial layer surrounded by a very thin layer of connective tissue with elastic fiber form this layer. 

This layer provides a smooth surface for easy flow of blood and also prevent from a blood clot. This layer is also known to release proteinaceous substances that regulate the arterial diameter. 

Types of Arteries

Based on the structure, arteries are mainly classified into 2 main types, viz. elastic arteries and muscular arteries.

  1. Elastic Arteries

These are the arteries that have a considerable amount of elastic fibers as their structural component in their tunica media layer. These arteries can expand and contract more significantly than other arteries due to the presence of elastic fibers. The Aorta, major branches of the aorta, and other major arteries (larger arteries) are elastic arteries. 

  1. Muscular Arteries

These arteries have a low amount of elastic fibers in the tunica media but contain a very high proportion of muscle cells.  These arteries are branches of major arteries and function to supply blood to organs and tissues.

Based on the types of blood they carry and the location of delivery, arteries can be classified into two types, viz. pulmonary arteries and systemic arteries. 

  1. Systemic Arteries

These arteries supply oxygenated blood from the left ventricle to every tissue of the body for cellular respiration and nutrient circulation. 

  1. Pulmonary Arteries

These arteries carry deoxygenated blood collected by veins from the right ventricle to the lungs for re-oxygenation i.e. exchange of metabolic CO2 with the atmospheric O2 at the alveoli of the lungs. 

Some of the major arteries are summarized in the table below.  

The Sections of the Aorta
Ascending AortaAortic ArchThoracic AortaAbdominal Aorta
Major Arteries Arising from the Sections of the AortaThe left and the right coronary arteriesBrachiocephalic trunk

Left common carotid artery

Left subclavian artery

Axillary artery

Branchial artery

Radial and ulnar artery
Intercostal arteries (10 pairs) Celiac trunk

Superior mesenteric artery

Renal arteries

Gonadal arteries

Lumbar arteries

Inferior mesenteric artery

Common iliac arteries

Functions of Arteries

  • Systemic arteries carry the oxygenated blood from the heart to every organ and tissue of the body. Hence, their major function is to transport oxygen, nutrients, hormones, and other biomolecules or components to every part of our body. 
  • The elasticity of the arterial wall functions to propel the blood together with the pumping action of the heart. 
  • Pulmonary arteries carry the deoxygenated blood from the right ventricle to the lungs for oxygenation. 

Arteries and Diseases

Arteries suffer from various medical conditions called arterial diseases. They may be infectious diseases caused by microorganisms or maybe other non-infectious medical conditions.

Coronary Artery Disease
Coronary Artery Disease

Some of them are tabulated below:

Disease Introduction
Aortic DiseaseThe conditions where the aorta experiences some abnormalities like dilation and bulging of the wall (aneurysm).  
Coronary Artery DiseaseCondition when the coronary arteries fail to transport blood smoothly to the heart muscles due to blockage or inflammation.
Peripheral Artery DiseaseCondition when the systemic arteries fail to transport blood smoothly due to blockage or inflammation or constriction.
Pulmonary EmbolismCondition due to blockage of an artery supplying to the lungs mostly due to the formation of a blood clot.
AtherosclerosisDevelopment of abnormalities called lesions in the arterial walls and stiffening of the arterial walls.


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About Author

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Prashant Dahal

Prashant Dahal completed his bachelor’s degree (B.Sc.) Microbiology from Sunsari Technical College, affiliated with Tribhuvan University. He is interested in topics related to Antimicrobial resistance, the mechanism of resistance development, Infectious diseases (Pneumonia, tuberculosis, HIV, malaria, dengue), Host-pathogen interaction, Actinomycetes, fungal metabolites, and phytochemicals as novel sources of antimicrobials and Vaccines.

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