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 System,”
the structures and functions that carry
blood throughout the body. An amazing pump—
the heart—and miles of blood vessels—the arteries
and veins—are the hallmarks of this system
that mostly functions without conscious awareness
save for the regular rhythm of the heartbeat.
Advances in medical technology make it possible
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 substitutes,
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 System”
discuss these sophisticated therapeutic
approaches. Yet lifestyle strongly influences cardiovascular
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 circulatory
networks. The blood bridges the functions
of the cardiovascular and pulmonary systems, circulating
through arteries, veins, and capillaries to
The Immune System and Allergies
The immune system is a complex network of primarily
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 conxiii
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 characteristic
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 junctions,
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 interacts
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 provide
both discussion and cross-references to establish
such connections.