Endocrine System: Hormonal Feedback, Pregnancy, and Pheromones

Vocabulary flashcards covering hormones, feedback mechanisms, reproductive physiology, and pheromones from the lecture.

GnRH (Gonadotropin-Releasing Hormone)

A hypothalamic hormone that stimulates the anterior pituitary to release gonadotropins (LH and FSH); its secretion can be increased by estradiol surges (positive feedback).

Estradiol

A potent estrogen produced by the ovaries; high levels promote GnRH release (positive feedback) and drive the cycle.

Positive feedback

A regulatory loop in which rising hormone levels promote further release of that hormone or its upstream activator (e.g., estradiol surges increasing GnRH).

Negative feedback

A regulatory loop in which rising hormone levels suppress upstream hormone production, dampening the system (e.g., progesterone reducing GnRH).

Progesterone

A pro-pregnancy hormone produced after fertilization; maintains pregnancy and helps shut off estrogen-driven signaling by signaling the uterus/placenta to sustain gestation.

Pregnancy

State following fertilization where the embryo implants in the uterus and progesterone supports maintenance of the pregnancy.

Ovary

Gonad where estrogen (estradiol) is primarily produced; later contributes to progesterone production during pregnancy.

Placenta

Organ that supports pregnancy and becomes a major source of progesterone as gestation progresses.

Estrogen

Class of sex hormones including estradiol; promotes development and maintenance of female reproductive tissues.

Shutoff valve (progesterone effect)

Metaphor for progesterone’s role in dampening or ending the estrogen-driven hormone cascade.

Steroid hormones

Lipid-soluble hormones (e.g., estrogen, progesterone) that cross cell membranes and regulate gene expression via intracellular receptors.

Protein (peptide) hormones

Water-soluble hormones that bind to surface receptors and trigger second messenger systems; do not typically cross cell membranes.

Pheromones

Chemical signals released by individuals to affect the behavior or physiology of conspecifics; often linked to reproduction and communication outside the endocrine system.

Volatile pheromones

Airborne pheromones that can be detected in the environment via inhalation by other individuals.

Olfactory bulb

Brain region that processes smells and pheromone signals; essential for detecting pheromones via chemoreceptors.

Chemoreceptors

Sensory receptors that detect chemical signals (like pheromones) and relay information to the brain.