File:XXhpgaxis.jpg

The female endocrine Hypothalamic–Pituitary–Gonadal (HPG) axis.

The hypothalamus produces and secretes luteinizing hormone–releasing hormone (LHRH) into a system of blood vessels that link the hypothalamus and the pituitary gland. LHRH stimulates the pituitary gland by attaching to specific molecules (i.e., receptors).

After the coupling of LHRH with these receptors, a cascade of biochemical events causes the pituitary gland to produce and secrete two hormones, luteinizing hormone (LH) and follicle–stimulating hormone (FSH). LH and FSH are two of a class of hormones commonly known as gonadotropins.

They are secreted into the general circulation and attach to receptors on the ovary, where they trigger ovulation and stimulate ovarian production of the hormones estrogen and progesterone.

These female hormones cause monthly menstrual cycling and have multiple effects throughout the body. In particular, estrogen has profound effects on the skeletal system and is crucial to maintaining normal bone health (Kanis 1994).

Image Source: NIAAA Alcohol’s Effects on Female Reproductive Function, Mary Ann Emanuele, M.D., Frederick Wezeman, Ph.D., and Nicholas V. Emanuele, M.D.

Figure 1

http://pubs.niaaa.nih.gov/publications/arh26-4/274-281.htm