Understanding Menstruation

Understanding menstruation requires a bit of biology. First, you must understand the interaction between the reproductive organs-- the uterus, the cervix, the vagina, the ovaries, and the fallopian tubes--and the role hormones play in your monthly cycle. The uterus is a pear-shaped organ which, in its non-pregnant state, is collapsed and about the size of your fist. It is located between the bladder and the lower intestines.

The lower third of the uterus is called the cervix. The cervix has an opening called the os which opens into the vaginal canal and permits your period to flow out.

Extending from each side of the uterus are the fallopian tubes. Near the end of each fallopian tube is an ovary.

The ovaries are almond-sized organs which produce eggs. Each ovary contains from 200,000 to 400,000 follicles. These follicles contain the material necessary to produce eggs.

The inner lining of the uterus is called the endometrium. The endometrium sheds during menstruation. Your menstrual flow also contains blood and mucus from the cervix and vagina. When pregnancy occurs, the endometrium thickens and fills with blood vessels that mature into the placenta that houses the growing fetus.

The area of the brain called the hypothalamus, together with the pituitary gland, control the hormones necessary for reproductive health.

There are 6 hormones that serve as chemical messengers to your reproductive system: Gonadotropin-releasing hormone (GnRH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Estrogen Progesterone Testosterone

During your menstrual cycle, GnRH is released first by the hypothalamus. This causes a chemical reaction in the pituitary gland and stimulates the production of FSH and LH. Estrogen, progesterone, and testosterone (yes, the male hormone) are produced by the ovaries in reaction to stimulation by FSH and LH. When these hormones work in unison, normal menstrual cycles occur.

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