Women's Health I: The Menstrual Cycle and HPO Axis/GYN visit

Vocabulary flashcards covering the key terms, hormones, phases, and physiological concepts of the menstrual cycle and hypothalamic-pituitary-ovarian (HPO) axis from Women's Health I.

Hypothalamic-Pituitary-Ovarian (HPO) Axis

The neuroendocrine system consisting of the hypothalamus, anterior pituitary gland, and ovaries that regulates female reproductive physiology via stimulatory and inhibitory feedback loops.

Hypothalamus

A brain structure that controls anterior pituitary function by secreting releasing and inhibiting factors (such as pulse-released GnRH) to regulate the gynecologic system.

Gonadotropin-Releasing Hormone (GnRH)

A hormone released in pulses by the hypothalamus that signals the anterior pituitary gland to release Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH).

Follicle Stimulating Hormone (FSH)

A gonadotropin released by the anterior pituitary that travels to the ovaries to stimulate follicular growth and estrogen production.

Luteinizing Hormone (LH)

A gonadotropin released by the anterior pituitary that acts on the ovaries to trigger ovulation and support progesterone production.

Four Key Gonadotropins

The core hormonal messengers of the HPO axis: Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Estrogen, and Progesterone.

Menstrual Phase

The initial phase of the menstrual cycle, triggered by a drop in circulating estrogen and progesterone following corpus luteum involution.

Follicular Phase

The ovarian phase starting on day $1$ of menses and ending on the day of the LH surge, focused on developing a dominant follicle and secondary oocyte.

Approximate timing of the LH surge prior to ovulation

Day 10-14.

Dominant Follicle

The single ovarian follicle with the highest density of FSH receptors that continues to mature and produce peak estrogen levels while other recruited follicles undergo atresia.

LH Surge

The sudden surge of LH triggered by peak estrogen levels near the end of the follicular phase, serving as the most reliable single indicator of impending ovulation.

Ovulation

The release of an oocyte from the ruptured dominant follicle (induced by prostaglandins and proteolytic enzymes), occurring $10\text{ to }12\,\text{hours}$ after the LH surge and $24\text{ to }36\,\text{hours}$ after the estrogen peak.

Fertilization Window

The period lasting $12\text{ to }24\,\text{hours}$ after oocyte release during which fertilization can occur inside the fallopian tube.

Corpus Luteum

A temporary endocrine structure formed from the transformed dominant follicle post-ovulation that produces high levels of progesterone, peaking $7\text{ to }8\,\text{days}$ after ovulation.

Luteal Phase

The ovarian phase starting with ovulation and ending with menstruation, fixed at $14\,\text{days}$ in length, characterized by high progesterone levels that suppress GnRH.

Proliferative Phase

The endometrial phase following menses and ending at ovulation, driven by estrogen, during which endometrial thickness increases from $1\text{ to }2\,\text{mm}$ to $8\text{ to }12\,\text{mm}$.

Secretory Phase

The endometrial phase following ovulation where progesterone downregulates estrogen receptors and matures the endometrium (increasing vessel coiling and gland tortuosity) for embryo implantation.

Human Chorionic Gonadotropin (hCG)

A hormone produced by blastocyst cells that prevents corpus luteum involution, maintaining progesterone production until the placenta takes over around week $12$.

Spinnbarkeit

The high elasticity and stretchability characteristic of cervical mucus during periovulation, occurring alongside thin, clear, high-volume mucus with ferning.

Stratum Functionalis

The superficial layer of the endometrium that disintegrates and sheds during menstruation due to prostaglandin-mediated vasoconstriction of spiral arteries and tissue hypoxia.

Stratum Basale

The innermost layer of the endometrium that remains intact during menses and regenerates the functional layer in subsequent cycle phases.

HPO Axis Dysfunction Consequences

Pathological conditions resulting from disruptions along the HPO axis, including amenorrhea, anovulation, infertility, and irregular menstrual cycles.

5 P’s of a sexual health history intake

Partners, practices, protection from STI’s, past history of STI’s, pregnancy intention or preventions .

Name 4 aspects of trauma-informed care

Recognizes the widespread impact of trauma; prioritizes safety, trustworthiness, empowerment, collaboration and cultural humility; seeks to avoid re-traumatization; assumes anyone could have experienced trauma.

What type of language do you provide for your GYN exam?

Gender neutral.