The female reproductive system produces egg cells, supports fertilization, and can nourish a developing embryo during pregnancy. Its main organs include the ovaries, fallopian tubes, uterus, cervix, and vagina. Understanding this system helps explain puberty, the menstrual cycle, fertility, pregnancy, and many common health conditions.
It also shows how structure and function work together in a complex body system.
Each menstrual cycle is controlled by changing levels of hormones from the brain and ovaries. Follicle stimulating hormone and luteinizing hormone help regulate the ovaries, while estrogen and progesterone help regulate the uterus. Ovulation releases an egg from an ovarian follicle, and the uterine lining changes to prepare for possible implantation.
If fertilization and implantation do not occur, hormone levels fall and menstruation begins.
Key Facts
- Ovaries produce oocytes, estrogen, and progesterone.
- The fallopian tubes, or oviducts, move the oocyte toward the uterus and are the usual site of fertilization.
- Ovulation is triggered by a surge in luteinizing hormone, often written as an LH surge.
- A typical menstrual cycle is about 28 days, but normal cycles can vary from about 21 to 35 days.
- The endometrium thickens under the influence of estrogen and progesterone to prepare for implantation.
- If fertilization does not occur, estrogen and progesterone decrease, causing the endometrium to shed as menstruation.
Vocabulary
- Uterus
- The uterus is a muscular organ where the endometrium thickens each cycle and where an embryo can develop during pregnancy.
- Ovary
- An ovary is a gland that contains follicles, releases oocytes, and produces estrogen and progesterone.
- Fallopian tube
- A fallopian tube is a duct that carries an oocyte from the ovary toward the uterus and is the most common site of fertilization.
- Endometrium
- The endometrium is the inner lining of the uterus that thickens during the cycle and is shed during menstruation if pregnancy does not occur.
- Corpus luteum
- The corpus luteum is the structure formed from a ruptured ovarian follicle after ovulation that secretes progesterone and some estrogen.
Common Mistakes to Avoid
- Calling the vagina the whole reproductive system is incorrect because the vagina is only one canal, while the system also includes the ovaries, fallopian tubes, uterus, and cervix.
- Thinking fertilization usually happens in the uterus is incorrect because fertilization most commonly occurs in the fallopian tube.
- Assuming ovulation and menstruation happen at the same time is incorrect because ovulation usually occurs about two weeks before menstruation in a typical cycle.
- Forgetting the role of progesterone is incorrect because progesterone from the corpus luteum helps maintain the thickened endometrium after ovulation.
Practice Questions
- 1 A student has a 28 day menstrual cycle. If menstruation begins on day 1 and ovulation occurs about 14 days before the next period, on about which day does ovulation occur?
- 2 A menstrual cycle lasts 32 days. Estimate the day of ovulation if ovulation occurs about 14 days before the next period begins.
- 3 Explain why damage or blockage in a fallopian tube can reduce fertility even if the ovaries and uterus are functioning normally.