Artery

Arterial System en

An artery is a type of blood vessel that is specifically designed to carry blood away from the heart. Unlike veins, which return blood to the heart, arteries transport blood to various parts of the body to ensure the delivery of oxygen and essential nutrients to cells and tissues.

Types of Arteries

• Pulmonary Arteries: These arteries are responsible for carrying blood that is relatively low in oxygen content from the right ventricle of the heart to the lungs. Here, the blood is oxygenated before being sent back to the heart.
• Systemic Arteries: These arteries convey oxygen-rich blood from the left ventricle of the heart to the rest of the body tissues.

Structure and Function

Blood is thrust from the ventricles into expansive elastic arteries. These arteries then undergo repeated branching, evolving into progressively smaller arteries until they culminate in minuscule arteries known as arterioles. Arterioles are instrumental in steering blood flow into the tissue capillaries. The systemic arterial system contains approximately 10% of the body's total blood volume at any given point.

Artery Wall Structure

The wall of an artery can be divided into three distinct layers:

Histopathology of arcuate artery nephrosclerosis

1. Tunica Intima (or Tunica Interna): This innermost layer is made up of simple squamous epithelium that is ensconced by a connective tissue basement membrane embedded with elastic fibers.
2. Tunica Media: Predominantly comprised of smooth muscle, this middle layer is usually the most substantial. Apart from providing support to the vessel, it plays a pivotal role in adjusting the vessel diameter, which in turn influences blood flow and blood pressure.
3. Tunica Externa (or Tunica Adventitia): This outer layer, which secures the vessel to the neighboring tissue, is constructed from connective tissue integrated with a mix of elastic and collagenous fibers. Near the tunica media, the connective tissue is denser, becoming more lax towards the vessel's periphery.

Capillaries

Capillaries stand as the tiniest and most abundant blood vessels, forging the link between arteries and veins. Their main role is to facilitate the exchange of substances between blood and tissue cells.

Depending on the metabolic demands of body tissues, the distribution of capillaries varies. Tissues that are metabolically active, such as the liver, kidneys, and skeletal muscles, have intricate capillary networks due to their increased need for oxygen and nutrients. In contrast, tissues like connective tissues possess fewer capillaries. It's worth noting that the epidermis of the skin, as well as the lens and cornea of the eye, are devoid of capillaries. Approximately 5% of the overall blood volume resides in the systemic capillaries at any given time, with an additional 10% situated in the lungs.

Regulation of blood flow from arterioles into capillaries is managed by smooth muscle cells located in the arterioles, right at their branching point to form capillaries.

See also

• Veins
• Blood circulation
• Heart
• Cardiovascular system

Also see veins.

Artery Resources
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