"What is a hormone?"
In simplest terms, hormones are chemical messengers that course through your bloodstream and enter tissues where they turn on switches to the genetic machinery that regulate everything from reproduction to emotions, general health, and well being. Hormones can be thought of as the life-giving force that animates you physically, mentally, and emotionally.
"Where are hormones made?"
Different glands and organs throughout the body produce hormones:
· the pancreas produces the hormone insulin;
· the ovaries produce estrogens and
progesterone;
· other glands, such as the pituitary and
hypothalamus in the brain, secrete hormones
such as FSH (follicle stimulating hormone) and
LH (luteinizing hormone) that control how much
estrogen and progesterone are produced by the
ovaries.
"The Steroid Hormone Family"
Some hormones are composed of large proteins and others of small fatty substances derived from cholesterol. One class derived from cholesterol belongs to a family of hormones termed steroids. The steroid family is broken down into five major categories including including:
· the estrogens (estradiol, estriol, estrone),
· progesterone,
· androgens (DHEA, testosterone,
androstenedione),
· glucocorticoids (cortisol, cortisone),
· mineralcorticoids (aldosterone).
Cholesterol is converted to the mother steroid hormone, pregnenolone, which is then further converted in the ovaries, testes, and adrenal glands to the other hormones, as directed by protein hormone signals from the brain.
"The Brain Controls Steroid Hormone Synthesis"
How much, and what type of steroid hormone is produced is controlled by specific chemical messages from the brain.
· In women, the brain message FSH (follicle stimulating hormone) signals the ovaries to
produce estrogens. LH (luteinizing hormone), produced during the second half of the menstrual cycle then signals the ovaries to produce progesterone, which helps to balance and slow estrogen-stimulated growth.
· In men, LH signals the testes to manufacture testosterone.
· Stress—physical, emotional, or dietary—signals the brain to produce ACTH (adrenocorticotropin hormone), which in turn signals the adrenal glands to produce cortisol that regulates glucose levels in the blood and activates immune response to foreign invaders such as viruses and bacteria.
· There are complex interactions between hormones and neurotransmitters (Epinephrine, Norepinephrine, Glutamate, Dopamine, Serotonin and GABA). These interactions modulate their effectiveness, salience, mood and the perception of pain.
"Why only some tissues respond to hormones"
Once the steroid hormones are released into the bloodstream, they are carried within seconds to different tissues throughout the body. While all cells of the body are bathed in the steroid hormones, only some respond to the hormone signal. For example, cells in the breast, uterus, and brain respond to estrogens, whereas muscle cells do not.
Response to a specific hormone requires the presence of a specific steroid-binding receptor protein within the cell. When the steroid enters the cell, it binds and activates the receptor, which in turn, activates unique gene sites that orchestrate the production of new cell products such as enzymes, structural proteins, and new receptors to other hormones. For example:
· Estrogens bind to estrogen receptors in cells of the breast and uterus and trigger the synthesis of
growth-promoting factors, leading to cell growth and division.
· Estrogens also induce receptors for progesterone, allowing subsequent cell response to
progesterone produced during the luteal phase of the menstrual cycle.
· Progesterone, through its own receptor system, invokes the synthesis of its own unique cell
products, including secretory proteins (needed for the fertilized egg to adhere to the wall of the
uterus) and proteins that down-regulate the receptor for estrogen, shutting off further tissue
response to estrogens.
· In the brain, estrogens promote synthesis of neurotransmitters such as serotonin, essential for
normal brain function. Estrogens also modulate dopamine, the neurotransmitter responsible for
salience.
Each of the different steroid hormones is responsible for regulating thousands of unique and different cellular products needed for general cell maintenance and repair as well reproduction, immune modulation, and brain function. In short, steroid hormones are powerful molecules essential for maintaining physical and mental health. So it is not difficult to see why an imbalance of any one hormone can throw your physical and mental health out of balance, causing aggravating and even serious health problems.
As we age, we may develop an imbalance or deficiencies in hormones. This may produce symptoms that range from annoying, e.g. hot flashes, to dangerous, e.g. broken bones from osteoporosis, or heart disease. Testing and correction of hormone deficiencies and imbalances is available through Piedmont Physical Medicine.
