What is the Function of Hormones?
The function of hormones is many. Hormones are chemical messengers that regulate bodily functions. Hormones are made in cells of glands. They are then transported by the blood to other tissues/organs in the body stimulating cells into action. Like a thermostat hormones are regulated by negative and positive feedback loops that maintain hormone levels in a certain physiologic range.
Hormones work in close conjunction with the nervous system and some prefer to refer to that linked relationship as the neuroendocrine system.  Along with the nervous system, hormones enable cells in one part of the body to communicate with cells in another part. This video provides a simple overview of how hormones work.
Hormones make the many biochemical and neurochemical processes of the body operate more efficiently and effectively. We can live with suboptimal levels of hormones, but we can live far better with optimal levels. Restoring hormone levels to healthy levels through hormone replacement is primarily a quality of life decision. But, studies do also show that hormone levels in the upper third of the reference range is associated with lower mortality rates than levels in the lower third to the reference range.
Most hormone levels decline with aging (cortisol and insulin tend to be exceptions). Some of that decline may not necessarily be related to aging, but rather related to lifestyle habits. A key to youthful aging is to maintain hormone balance.
The Main Hormones Involved in Replacement Therapy
In this discussion we are going to focus on hormones involved in hormone replacement therapy. Many of these hormones are derived from cholesterol (cholesterol has many health benefits contrary to popular belief) and are called steroid hormones. They are fat soluble and made in the gonads and adrenal glands.
Function of Hormones
Pregnenolone is a steroid hormone made in the adrenal glands and precursor to estrogen, progesterone, testosterone, and adrenal hormones.  In the brain pregnenolone improves nerve transmission and memory. It inhibits pain and inflammation. It has been used to treat depression, memory loss, arthritis, and fatigue
DHEAÂ is a steroid hormone and the most abundant hormone we make. It is made in the adrenal glands and is also a precursor hormone to estrogen, progesterone, and testosterone. DHEA promotes weight loss, improves bone density, lowers cholesterol, improves brain function and mood, improves immune function, and enhances tissue repair.
Estrogen is a steroid hormone largely made in the ovaries. Estrogen is really a group of hormones of which there are 3 main ones in women; estrone, estradiol, and estriol. Estradiol is the most important. Estradiol plays a major role in reproduction and sexual function. It affects mood and bone density. Many symptoms of menopause are related to low estrogen.
Progesterone is a steroid hormone also largely produced in the ovaries. Progesterone regulates the menstrual cycle along with estrogen. It enhances blood flow, strengthens bones, and also affects brain and mood function. It typically has a calming effect.
Testosterone is a steroid hormone made in the testes in men and ovary and adrenal glands in women. Testosterone is responsible for secondary male sex characteristics. It helps to build muscle and bone. In the brain testosterone gets converted into estradiol which has positive effects on the brain, mood, and emotions.
Thyroid is made in the thyroid gland found in the front aspect of the neck. The main thyroid hormones are T3 and T4. T3 is the most biologically active. T4 gets converted into T3 but that conversion is affected by age, medications, and illness. In that sense T4 is a prohormone. Thyroid hormones regulate metabolism and essentially make the many organ-systems of the body work faster and more efficiently. The brain works faster, the GI tract moves faster,  the cardiovascular system works faster improving circulation, etc.
Melatonin is made in the pineal, a small pea-size gland in the brain. Melatonin helps to regulate sleep. It’s a powerful antioxidant. It enhances immune function and can improve the release of sex hormones and growth hormone, and decreases cortisol – the stress hormone. Medications (many blood pressure meds) and high glycemic meals can lower melatonin.
Growth hormone is made in the anterior pituitary gland in the brain. In adults growth hormone is primarily a healing hormone. It is released during deep sleep and after vigorous exercise with smaller pulses being release throughout the day. Many of the effects of growth hormone are mediated through IGF-1. Growth hormone improves body composition, improves central nervous system function, enhances skin thickness, repairs tissues, and potentiates the effects of many of the other hormones.
See related articles.
Melatonin: The Other Anti Aging Hormone
