Medical Terminology Simplified

Anatomy and Physiology Overview

The cardiovascular (CV) system is composed of the heart, which is essentially a muscular pump, and an extensive
network of blood vessels. The main purpose of the CV system, also called the circulatory system, is to deliver oxygen,
nutrients, and other essential substances to body cells and remove waste products of cellular metabolism. This process
is carried out by a complex network of blood vessels that includes arteries, capillaries, and veins—all of which are con-
nected to the heart. A healthy CV system is vital to a person’s survival. A CV system that does not provide adequate
circulation deprives tissues of oxygen and nutrients and fails to remove waste, resulting in irreversible changes to cells
that could be life-threatening.
The lymphatic system is closely linked to the CV system and depends on the pumping action of the heart to circulate
its substances throughout the body. The lymphatic system consists of a network of vessels and nodes, and a few spe-
cialized organs, including the tonsils, thymus, and spleen. Blood flows from the heart to blood capillaries and back to
the heart. Lymph capillaries collect tissue fluid, which is returned to the blood. (See Fig. 5–1.)

156 CHAPTER 5• Cardiovascular and Lymphatic Systems

Subclavian vein

Lymphatic

vessel

Valve

Lymph
node

Heart

Lymph

flow

Lymph

capillaries

Blood

capillaries

Blood

flow

Artery

Figure 5-1Interrelationship of the

cardiovascular and lymphatic system, in

which the blood flows from the heart to

blood capillaries and back to the heart

and lymph capillaries to collect tissue

fluid, which is returned to the blood

(arrows indicate the direction of blood

and lymph flow).