18.1: Introduction

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Rosanna Hartline
West Hills College Lemoore

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Introduction

Systemic arteries and veins, anterior views

Above: Overview of the systemic arteries and veins.

The cardiovascular system is responsible for transporting oxygen, nutrients, and waste materials around the body. These substances are dissolved or suspended in the blood tissue and carried around a system of tubes called blood vessels. If it were possible to stretch out all of the blood vessels in the body, they would measure 60,000 to 100,000 miles, enough circle the earth roughly four times.

As discussed in Chapter 17: Cardiovascular System - The Heart, there are two circuits of circulation from the heart: the pulmonary circuit and the systemic circuit. The pulmonary circuit transfers deoxygenated blood from the heart to the lungs and the oxygenated blood from the lungs back to the heart. The systemic circuit transports oxygenated blood from the heart to all of the body tissues and returns deoxygenated blood from the tissues to the heart. In anatomical diagrams, blood vessels carrying oxygenated blood are usually shown red and blood vessels carrying deoxygenated blood are usually shown blue. It is for this reason that blood vessels in the systemic circuit that are shown as red in anatomical diagrams are either arteries or arterioles (carrying oxygen-rich blood away from the heart and toward the body tissues) and blood vessels in the systemic circuit that are shown blue are either veins or venules (carrying oxygen-poor blood toward the heart from the body tissues). The terms arteriole and venule are terms used to describe blood vessels that are smaller in size than arteries and veins, respectively.

The smallest blood vessels of the body are the capillaries. This is where transfer of oxygen, nutrients, and waste materials occurs between the blood and the body tissues.

Attributions

"Blood vessels" by Professor Philip Cowley is licensed under CC BY-NC-SA 4.0
"Human Anatomy Lab Manual" by Malgosia Wilk-Blaszczak, Mavs Open Press, University of Texas at Arlington is licensed under CC BY 4.0