< previous page page_10 next page >

Page 10
The Normal Female
Reproductive Cycle
The Hypothalamus and Pituitary
The normal cycle in the human female involves a complex communication among several glands and organs. In the brain an area known as the hypothalamus, a master control center for many bodily functions, secretes gonadotropin-releasing hormone (GnRH). This hormone signals the pituitary gland, a tiny gland in the brain which is attached to the hypothalamus by way of the hypothalamic-pituitary axis, to secrete several hormones depending on the perceived needs of the body. In the case of the gonadotropin-releasing hormone from the hypothalamus, the pituitary will secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones will in turn signal the production of estrogen and progesterone.
The Phases of the Cycle
The production and release of brain hormones basically divides the female endocrine cycle into three distinct phases. The first is known as the follicular or preovulatory phase. This phase begins on the very first day of the woman's bleeding and lasts approximately 14 days. During the beginning of that phase,

 
< previous page page_10 next page >

If you like this book, buy it!