It is said that modern endocrinology was born when the German zoologist and physiologist Arnold Adolph Berthold (1803-1861) carried out experiments in the 1800’s. He set out to determine what role the gonads, the ovaries and testicles, played in the development of secondary sex characteristics.
He saw that castrated cockerels never developed wattles (the reddish lobe hanging from the head or neck) or combs (the crest that grows on the crown), the way cockerels should. The cockerels also did not show typical male behavior after castration. I am thankful that we have come a long way since then.
The female hormones of the endocrine system help to regulate and maintain the health and functioning of the reproductive system as well as other areas. Part 1/3 explained that the female hormones produced by the ovaries are estrogen, progesterone and testosterone.
They play actually a variety of different roles in developing secondary sex characteristics, controlling fertility, and regulating menstrual cycles.
Sometimes problems cause a female hormone imbalance. These usually are associated with the ovaries, such as ovarian cysts, ovarian cancer, and polycystic ovarian syndrome. The differing levels of estrogen, progesterone, and testosterone throughout the month can cause mood swings and other behaviors.
Female Hormone, Estrogen
Estrogen is the most widely known hormone. Estrogen is actually the name for a group of three very similar hormones:
- estrone,
- estriol, and
- estradiol.
Uniquely responsible for reproduction: The estrogenic hormones are uniquely responsible for the growth and development of female sexual characteristics and reproduction in both humans and animals.
Estradiol in high volumes: Estradiol is the most highly produced of these hormones during the reproductive ages. The anterior pituitary sends follicle stimulating hormone (FSH) and luteinizing hormone (LH) to the ovaries, which causes them to release estrogen into the blood stream.
The pituitary and hypothalamus receive the message that estrogen and progesterone are being produced by the ovaries, and it slows or stops the release of LH and FSH. FSH causes some of the ovarian follicles to mature. A burst of LH is released from the pituitary, called the preovulatory LH surge, causing ovulation of the mature follicle in the ovary. The cells left around the released follicle form the corpus luteum.
Production location: The ovaries produce most of the estradiol and estrone, and the placenta produces estriol. The adrenal glands and fat tissues also produce some estrogen.
Estrogen targets cells that are located in areas that include the uterus, breasts, brain, heart, liver, and bone.
Estrogen is responsible for
- the female shape by controlling factors, such as
- limiting muscle mass and height, and
- plays a dominant role in breast formation during puberty and pregnancy.
- controlling the uterine lining growth during the first part of the menstrual cycle.
Moodswings: The differing levels of estrogen and progesterone throughout the month may cause mood swings.
Allopregnenolone, the body’s relaxation hormone, disappears in the days before the menstrual period. This is one of the causes of PMS.
Female hormone, Progesterone
One goal: Progesterone has actually only one goal and that is to thicken the uterine lining to prepare it for receiving a fertilized egg after ovulation has occurred. But is has several consequences when lacking as we see further.
Mechanics: As the mature egg travels through the fallopian tube on its way to the uterus, progesterone is released from the corpus luteum. We gave two options:
- If the egg becomes fertilized, it implants in the uterus. In this case, the corpus luteum continues to produce progesterone. LH is necessary for the continued growth and functioning of the corpus luteum. The placenta also begins to produce progesterone, which maintains the uterus during pregnancy. Progesterone helps to protect the fetus from the mother’s immune system. It keeps the mother’s body from rejecting the fetus as foreign. Women who have many miscarriages may need progesterone therapy to prevent this from happening.
- If pregnancy doesn’t occur, then progesterone levels quickly drop. Pregnant women’s progesterone levels are 10 times higher than non-pregnant women.
Contraception pills contain a compound that mimics progesterone, and is often combined with estrogen. The preovulatory surge of LH that causes ovulation doesn’t happen when on birth control, because these circulating hormones inhibit LH secretion.
And Female hormone: Testosterone
Although usually considered a male hormone, testosterone is also a female hormone. Comparable to estrogenic hormones that are sometimes mistakenly referred to as exclusively female hormones when in fact both men and women produce them. However, the role estrogen plays in men is not entirely clear.
Role: Testosterone is commonly known as the responsible hormone for our sex drive. Testosterone is indeed responsible for much of the female libido. In a more general way, it gives a supply of sassiness and a zest for life. Androstenedione is the precursor to testosterone. It slows at menopause and perishes along with the ovaries. After menopause, testosterone levels drop as well as estrogen levels. Testosterone levels fall to 50% of their prior level, and they are completely absent in some women.
Mechanics: Approximately 40% to 50% of the testosterone in a woman is produced in the ovaries and adrenal glands.
Hormonal imbalance
Overproduction of testosterone: A female hormone imbalance causing overproduction of testosterone results in physical changes that include a decrease in breast size, changes in body shape, excess hair growth, oily skin, and lack of a menstrual period. This could be due to an ovarian tumor, in which case the tumor is removed, and the symptoms usually disappear. These tumors are usually not cancerous, and they will not come back once removed. In the case of polycystic disorder, careful monitoring is necessary. There is no prevention known at this time, but maintaining a proper weight and exercising will help.
Estrogen drop: At the same time the testosterone levels are falling after menopause, estrogen levels also fall. A drop in estrogen causes symptoms that include
- Bone loss or brittle bones. After menopause your body breaks down more bone than it rebuilds. In the years immediately after menopause, women may lose as much as 20 percent of their bone mass.
- Vaginal dryness,
- Decreased sensitivity of the clitoris, and
- Thinning of the walls of the vagina. This may cause sex to be painful.
Estrogen replacement therapy after menopause not only addresses sexual dysfunction, but it helps to protect against osteoporosis and heart disease.
When a uterus is present, it is a good idea to also add progesterone to keep it from becoming cancerous. If estrogen replacement doesn’t correct the loss of interest in sex, then testosterone may be added. Extra estrogen does increase the risk of breast cancer by promoting breast tissue growth, however not everyone agrees on the degree of risk.
Oxytocin
Oxytocin is another female hormone released by the pituitary, and is often called the “love drug.”
Here are some examples of love:
- Suckling by the infant during breast feeding releases oxytocin, which causes milk ejection.
- Oxytocin is also released when the cervix dilates and it causes the uterine contractions.
- When the female hormone oxytocin is released by the mother during labor, it sends oxytocin across the placental wall to calm the baby while it is being born to protect against injury.
- Oxytocin increases a variety of good feelings :
- security,
- contentment,
- trust,
- empathy, and
- it plays a role in bonding.
Paul Zak, PhD, a researcher at Claremont Graduate University in Claremont, California, says the higher the oxytocin levels of a women, the happier she is. He commented that
“Those with higher oxytocin had more sex with fewer partners.”
Oxytocin and Bonding
Bonding is an important behavior necessary in forming relationships between a child and mother and between people, such as men and women. A 20 second hug between partners causes the release of oxytocin in their brains. Oxytocin triggers trust.
Its release is not caused by hugs but by positive emotional interactions, like:
- gazing into another’s eyes,
- touching,
- kissing, and off course
- orgasm.
The female hormones estrogen and progesterone also increase the effects of oxytocin and dopamine for a feel-good euphoria of sorts.
However, stress can turn off these happy chemicals. But is nice to know that oxytocin supplements in the form of a nasal inhaler do exist. They are actually often used in oxytocin research.
So, here you go. The female hormone, estrogen, along with progesterone, testosterone and others, play a large part of our daily lives for our entire lives. A female hormone imbalance could cause distress or physical illness. Knowledge about how to re-balance hormones has come a very long way. Luckily for women today, there are female hormone therapies to replace the lost hormones and regain functioning in all areas of life.
To know about these hormone replacement therapies, we have another article coming up: part 3/3!