Facts on File Encyclopedia of Health and Medicine

PREFACE TO VOLUME 2

Volume 2 of the four-volume The Facts On File
Encyclopedia of Health and Medicine presents the
body systems that nourish, cleanse, and protect
the body. These are the systems of cells and fluids
and the structures that transport them throughout
the body. Though distinct in their functions and
purposes, these systems overlap and integrate
with one another in inseparable ways.

The Cardiovascular System

Volume 2 opens with “The Cardiovascular Sys-
tem,” the structures and functions that carry
blood throughout the body. An amazing pump—
the heart—and miles of blood vessels—the arter-
ies and veins—are the hallmarks of this system
that mostly functions without conscious aware-
ness save for the regular rhythm of the heartbeat.
Advances in medical technology make it possi-
ble to treat cardiovascular disease that even 30
years ago would have been fatal. Medications and
devices can regulate the functions of the heart to
overcome or compensate for disease and damage.
Heart transplantation and mechanical heart sub-
stitutes, once the dream of surgeons but the
venue of fiction, are now among the standard
treatment options for some heart conditions.
Many of the entries in “The Cardiovascular Sys-
tem” discuss these sophisticated therapeutic
approaches. Yet lifestyle strongly influences car-
diovascular health, which encyclopedia users will
detect as a prevalent theme in this section.

The Blood and Lymph
These two fluid-based systems of the blood and
the lymph have separate yet interconnected circu-
latory networks. The blood bridges the functions
of the cardiovascular and pulmonary systems, cir-
culating through arteries, veins, and capillaries to

carry oxygen and nutrients to, and metabolic

wastes from, cells throughout the body. The cells

that do this work, the erythrocytes, make up

about half the blood’s cells and give blood its char-

acteristic red color. The lymph network is the

immune system’s major highway; its cells are

lymphocytes. These white blood cells lack color,

giving lymph the appearance of watery milk.

Lymph circulates through its own structure of

lymph vessels though crosses from the lymphatic

circulation to the blood circulation at two junc-

tions, the cisterna chyli and the thoracic duct.

The Pulmonary System

The pulmonary system is the body’s primary

interaction with the external atmosphere. The

lungs pull oxygen-bearing air deep into the body

where an intricate molecular exchange takes

place to load each outgoing breath with metabolic

waste. The laws of physics—particularly those

relating to relationships between pressure and

volume, regulate the functions of the pulmonary

system. The pulmonary system intimately inter-

acts with the blood and the cardiovascular system.

Without these interactions, the functions of the

pulmonary system are of little value to the body.

Acquired pulmonary disease often coexists with

cardiovascular disease; entries in this section pro-

vide both discussion and cross-references to estab-

lish such connections.

The Immune System and Allergies

The immune system is a complex network of pri-

marily cells and substances that circulate in the

lymph and the blood and reside in the tissues.

With much current research focused on HIV/AIDS

and the understanding and treatment of cancer,

knowledge of the immune system’s functions con-

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