Module 3S2 Chemistry of Reproduction

Lesson 2—Female Hormones

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Although there is a lack of scientific understanding of the hormonal process that triggers an embryo to undergo female sexual development, there is a very good understanding of what happens during puberty, the menstrual cycle, and as a woman ages. Being female is designated by the chromosomal arrangement of two X chromosomes, which causes a female to develop female genitalia, begin having a menstrual cycle and undergo menopause. The beginning of the menstrual cycle allows the female to fulfill her role in the continuation of the species.

The beginning of puberty is similar in men and women. For women, as well as men, the beginning of puberty is defined when the hypothalamus begins producing more gonadotropin releasing hormone (GnRH). GnRH then stimulates the anterior pituitary to start producing both follicle stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH then act on the female gonads, the ovaries, to produce the female sex hormones estrogen and progesterone. Once estrogen and progesterone are secreted, they cause the maturation and development of the female primary and secondary sex characteristics, and the start of the menstrual cycle.

When Jane, from the Fertility Case Study – Couple 1 – was in high school, she was a competitive gymnast. Her skill level was very good and she was competing at the provincial and national level. In her Grade 11 year Jane was 17, she was 5-foot-3 and weighed 95 pounds. What most people did not know was that Jane had had an eating disorder since she was 10, and at 17, she had not yet started menstruating. When she started training in Grade 12, she was even more fragile looking than ever.  Her coach, being concerned about her well being, stopped her from competing in several early competitions and decreased her training by 2/3 of what she would normally do. The coach also contacted her parents, who were also concerned by the frail look of their daughter. 

Jane discovered that when a woman of reproductive age is placed under physically demanding training regimes, the stress of competition, and an eating disorder, her body may suffer from the absence of a menstrual period, called amenorrhea. 

Jane knew she wanted children in her life one day, so she decided to learn more about how normal female reproductive hormone control should be working, and how her training and eating disorder were affecting her reproductive system. To understand what was happening to her body she needed more information to make better decisions in her life now and in the future. 

Focusing questions in this lesson are:

• What are the female reproductive hormones?
• How do hormones maintain homeostasis in the female reproductive system?
• What role do the female hormones play in regulating the primary and secondary sex characteristics?

Module 3: Section 2—Lesson 2 Assignment

No formal assessment will be given in this lesson. An assessment will be given after you have completed the lesson on the menstrual cycle.

Here is a tutorial video for this lesson that you can watch if it suits your learning style.  Bio30 2.3.2S2 Female Hormones