What Really Happens During Your Menstrual Cycle.

Do you know how many hormones play a role each month in causing your periods to be normal or abnormal? Can you name all of the parts of the female reproductive system? There is a delicate interaction between your reproductive organs and your hormones that influence the timing and amount of blood flow you experience during your monthly menstrual cycle. To understand how your reproductive organs and hormones interact first you should know something about the biology behind your menstrual cycle. Any change in your hormones or reproductive organs can have a significant affect the timing of your periods, the amount of blood flow you experience during menstruation, and your fertility.

What Are the Reproductive Organs?

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 contains the growing fetus.

What Hormones Interact with the Reproductive Organs?

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

Six hormones serve as chemical messengers to your reproductive system. These hormones include:

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.