Introduction: Genitals and Gender: What Makes Us Male and Female?
PART I The Endocrine System
Hormones Act in a Great Variety of Ways throughout the Body
RESEARCHERS AT WORK: Our current understanding of hormones developed in stages
Hormones are one of several types of chemical communication
Hormones can be classified by chemical structure
Hormones Act on a Wide Variety of Cellular Mechanisms
Hormones initiate actions by binding to receptor molecules
Hormones can have different effects on different target organs
BOX 8.1: Techniques of Behavioral Endocrinology
Each Endocrine Gland Secretes Specific Hormones
The posterior pituitary releases two hormones directly into the bloodstream
Posterior pituitary hormones can affect social behavior
Feedback control mechanisms regulate the secretion of hormones
Hypothalamic releasing hormones govern the anterior pituitary
Two anterior pituitary tropic hormones act on the gonads
The gonads produce steroid hormones, regulating reproduction
Hormonal and neural systems interact to produce integrated responses
PART II Reproductive Behavior
Reproductive Behavior Can Be Divided into Four Stages
Copulation brings gametes together
Gonadal steroids activate sexual behavior
RESEARCHERS AT WORK: Individual differences in mating behavior
The Neural Circuitry of the Brain Regulates Reproductive Behavior
Estrogen and progesterone act on a lordosis circuit that spans from brain to muscle
Androgens act on a neural system for male reproductive behavior
Maternal behaviors are governed by several sex-related hormones
The Hallmark of Human Sexual Behavior Is Diversity
Hormones play only a permissive role in human sexual behavior
PART III Sexual Differentiation and Orientation
Genetic and Hormonal Mechanisms Guide the Development of Masculine and Feminine Structures
Sex chromosomes direct sexual differentiation of the gonads
Gonadal hormones direct sexual differentiation of the body
Changes in sexual differentiation processes result in predictable changes in development
Dysfunctional androgen receptors can block masculinization of the body
Some people seem to change sex at puberty
SIGNS & SYMPTOMS: Defining an Athlete’s Sex
How should we define sex—by genes, gonads, genitals?
RESEARCHERS AT WORK: Gonadal hormones direct sexual differentiation of behavior and the brain
Early testicular secretions result in masculine behavior in adulthood
Several regions of the nervous system display prominent sexual dimorphism
Social influences also affect sexual differentiation of the nervous system
Do Fetal Hormones Masculinize Human Behaviors in Adulthood?
What determines a person’s sexual orientation?