Hormones! From PMS to menopause, these messengers of womanhood can affect your mood, your weight, your food cravings – even your desire for sex. For many women, it’s smooth sailing, but for others, it’s a shipwreck at every turn of the hormonal bend,” said Colette Bouchez an award-winning medical journalist.
Women’s bodies are chock full of hormones, and they don’t always cheer us up! Often, it is the opposite. Many of these female hormones are crucial to fertility. We know the beginning of the reproductive years starts with puberty, and the end of the fertile years is called menopause.
Most women often struggle with issues such as PMS and hormonal fluctuations throughout the month. Menopause is no cake walk, either. But if we understand our hormones, it may make it easier to cope. There are off course ways to ease the symptoms of these troubles through diet, exercise, and if necessary hormone replacement therapy (HRT).
But a better understanding of these hormone fluctuations throughout our lives will help deal with them, as well as help women who are trying to become mothers, because in the end, female fertility is in fact the sole purpose of several female hormones.
The Basics on Male and Female Hormones
Hormones are often referred to as “chemical messengers,” hormones carry information and instructions from one group of cells to another. But let’s dive deeper.
Secreted chemicals that travelling in the bloodstream: Hormones are chemicals secreted by specialized cells, groups of cells, or a neuron (then it’s called a neurohormone) into the blood which travel to a distant and specific target. Collectively, the secreting cells and the target cells are known as the endocrine system.
Really tiny: Hormones exert their control at very low concentrations: nanomolar concentrations (10-9 M) to picomolar concentrations (10-12 M).
Three types: A hormone can be
- an amine (derived from amino acids),
- a peptide (derived from proteins), or
- a steroid (derived from cholesterol).
Hormones from the pituitary that target the gonads (ovaries or testes) are called gonadotropins, and are peptide hormones. The sex hormones synthesized in the ovaries and testes are steroid hormones.
Receptor Binding mechanism: A particular hormone binds to specific receptors on the target cell and initiates further responses from that cell. Since hormones affect only their target cell’s receptor, they illicit no response from a cell lacking the correct receptor.
Limited time frame: Hormones act only for a limited time, and their levels must be controlled to be effective.
Negative-feedback system: All of the gonadotrophic female hormones are controlled by negative-feedback, except for oxytocin that uses positive feedback control.
The Hypothalamus and the Pituitary
Master switchboard: The hypothalamus is located above the pituitary gland and is called the “master switchboard”. It signals the pituitary, the “master gland” to synthesize and release hormones that regulate many bodily functions. The hypothalamus synthesizes two hormones in the neuronal cell body and sends them to the posterior pituitary through an axon. The two hormones are the anti-diuretic hormone and the female hormones oxytocin (OT).
The posterior pituitary then releases it into the blood stream. The anterior pituitary gland synthesizes and releases the other trophic female hormones. Trophic hormones cause the release of a different hormone at another location. In the case of female hormones, the target cells are in the ovaries.
The hypothalamus and the pituitary are intimately linked and in very close proximity. They are separated by a portal system of capillaries and neurons.
The pituitary is really two fused glands, called the anterior and posterior pituitary. The anterior pituitary secretes trophic female sex hormones. These are luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin. The posterior pituitary secretes the female neurohormone oxytocin.
- LH and FSH target the ovaries (testes in males) to control various sex characteristics and reproductive actions.
- Prolactin targets the breast tissue and carries the signal to begin milk production.
- Oxytocin triggers breast milk release during breast feeding, is responsible for uterine contractions during childbirth, and plays a role in maternal nurturing behavior and other kinds of bonding, such as emotional bonding with a partner.
The placenta also secretes hormones, but only when a woman is pregnant.
- Estrogens from the placenta ultimately prepare the uterus for the birthing process.
- Progesterone keeps the placenta in the proper state for fetal development, prevents the secretion of LH and FSH from the anterior pituitary to prevent ovulation, and suppresses uterine contractions.
- Chorionic somatomammotropin (CS), also called placental lactogens, is believed to control mother and fetal metabolism.
- Chorionic gonadotropin (CG) is produced by the fetus. It tells the body it is pregnant and prevents luteal regression. CG is the first chemical in the body that signals pregnancy.
- Relaxin is thought to work with progesterone for pregnancy maintenance, and also helps the ligaments in the pelvic region relax at the end of pregnancy to aid in the childbirth process.
This introduction to female hormones touches on the basics of the endocrine system, as it relates to reproduction. I find it helpful to start at the very beginning and work your way through the intricate mechanisms for a full understanding of what is happening in your body every month and when you are pregnant, or trying to become pregnant.
For further reading I highly recommend these books for a better understanding of female hormones: “The Female Brain“, by Louann Brizendine, reviews and prices here and “Human Physiology: An Integrated Approach, 4th Edition” by Dee Unglaub Silverthorn, reviews and prices here.
But if you have no time for reading these, then a further article (part 2) will focus on the functions of female hormones produced by the ovaries, the emotions and behaviors they may cause, and ways to possibly ease negative symptoms.