The Reproductive System
The organs, structures, and functions of the repro-
ductive system make possible the continuation of
human life. The reproductive system remains in a
state of immaturity until puberty, when the
endocrine system initiates hormonal changes to
stimulate the development of secondary sexual
characteristics. Hormones remain the foundation
of reproductive function for all of adulthood.
Pregnancy, the key function associated with the
reproductive system, represents an intricate physi-
ologic choreography in which female and male
gametes—ovum and sperm—unite to establish a
new life. The woman’s body carries the new life
for nearly 10 months, changing and adapting, as a
result of hormones, until it is capable of independ-
ent survival.
Psychiatric Disorders and Psychologic Conditions
Biochemical balance and imbalance are integral to
the functions and conditions that involve the mind
and emotions. The section “Psychiatric Disorders
and Psychologic Conditions” brings Volume 3 to a
close. Though much of the working of the mind
remains a mystery, researchers have made much
progress to understand the integrated functions of
the endocrine and nervous systems as they relate to
psychiatric disorders and psychologic conditions.
Pharmaceutical therapies (medications) to alter
neurotransmitter balances in the brain are often
the foundation of treatment approaches. Their
effects on neurologic function and emotional
processes can be profound, even when doctors do
not entirely understand the mechanisms of action
that produce such results.xiv Preface