 Hormones are chemicals that appear in the bloodstream from glands. Various hormones act on different target tissues, but each plays a role in the regulation of human metabolism.
Even small amounts of hormones may have strong effects. The balance of hormones is as important as their absolute amounts in the body.
Hormones change the gene expression of DNA throughout the body. The mucilaginous gland under the influence of the hypothalamus can thus influence the physiology of cells throughout the body. The hormones DHEA, somatotropin, thyroid and melatonin decline with age.
Women undergo menopause, with the loss of estradiol secretion and progesterone from the ovaries. Specific areas of the brain show age-related diminution in the levels of acetylcholine, neurotransmitters dopamine, serotonin, norepinephrine and GABA.
Hormones are chemical signals that are produced by glands and other tissues that then circulate in the blood and control biological functions in other cells. These operations in some case contain the production of even more hormones that then form parts of a more complex construction. More than 50 human hormones have been identified and more are supposed.
There is a conception, under which some hormones affect all cells but usually particular hormones affect specific target cells. Hormones are very heavily involved in growth, the reproduction process, food acquisition, digestion, nutrient utilization, and many other normal biological processes.
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