The Menstrual Cycle – Key Vocabulary

A set of vocabulary flashcards summarizing essential terms, phases, hormones, and structures involved in the menstrual cycle.

Menarche

The onset of a female’s first menstrual period; average age is about 12 years.

Menstruation

Monthly shedding of the endometrium when fertilization does not occur, typically every 26-32 days.

Ovarian Cycle

One of the two concurrent menstrual cycles; develops ovarian follicles, triggers ovulation, and forms the corpus luteum. Consists of follicular, ovulation, and luteal phases.

Uterine Cycle

Cyclical changes in the endometrium driven by hormones to prepare for possible implantation; includes proliferative, secretory, ischemic, and menstrual phases.

Follicular Phase

Days 1-14 of the ovarian cycle when follicles grow; stimulated mainly by FSH after GnRH release.

Ovulation

Mid-cycle (day 14) rupture of the mature follicle releasing an oocyte; triggered by a surge of LH.

Luteal Phase

Days 15-28 of the ovarian cycle; corpus luteum forms and secretes hormones until menstruation begins.

Proliferative Phase

Days 5-14 of the uterine cycle when the endometrium thickens under estrogen influence; parallels the follicular phase.

Secretory Phase

Day 15 to ~3 days before menses; endometrium becomes highly vascular and glandular under progesterone from the corpus luteum.

Ischemic Phase

Brief phase when declining estrogen and progesterone cause uterine arterioles to constrict, leading to tissue ischemia.

Menstrual Phase

Days 1-4 of the uterine cycle marked by shedding of the endometrial lining due to a sharp drop in estrogen and progesterone.

Gonadotropin-Releasing Hormone (GnRH)

Hypothalamic hormone that initiates the menstrual cycle by stimulating the anterior pituitary to release FSH and LH.

Follicle-Stimulating Hormone (FSH)

Anterior pituitary hormone that promotes growth of ovarian follicles during the follicular phase.

Luteinizing Hormone (LH)

Anterior pituitary hormone that triggers ovulation and supports corpus luteum formation.

Estrogen

Ovarian hormone that stimulates endometrial proliferation and contributes to secondary sex characteristics; rises during the follicular and proliferative phases.

Progesterone

Hormone secreted mainly by the corpus luteum after ovulation; prepares and maintains the endometrium for implantation.

Corpus Luteum

Hormone-secreting structure formed from the ruptured follicle after ovulation; produces progesterone and some estrogen.

Oocyte

The mature egg cell released during ovulation; viable for about 24 hours.

Endometrium

Innermost uterine layer that undergoes cyclical changes during the uterine cycle.

Myometrium

Thick smooth-muscle middle layer of the uterus responsible for contractions.

Perimetrium

Serosal outer layer covering the body of the uterus.

Hypothalamus

Brain region that secretes GnRH, serving as the first hormonal control center of the menstrual cycle.

Anterior Pituitary Gland

Endocrine gland that releases FSH and LH in response to GnRH, orchestrating ovarian events.

Corpus Albicans

Scar-like structure that forms when the corpus luteum degenerates if pregnancy does not occur.

Menstrual Cycle Length

Typical interval of 26-32 days from the first day of one menses to the first day of the next.