Hormones: chemical "messengers" secreted into the bloodstream primarily by “endocrine glands.” (Hockenbury, 54)

Glandular secretions that affect bodily functions or "behavior." (Coon, 75) One of many chemicals made by "glands" in the body. Hormones circulate in the bloodstream and control the actions of certain "cells" or "organs." Some hormones can also be made in the laboratory. (NCIt) Chemical substances having a specific regulatory effect on the activity of a certain organ or organs. The term was originally applied to substances secreted by various endocrine glands and transported in the bloodstream to the target organs. It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects. (MeSH)

Catecholamines: hormones secreted by the “adrenal medulla” that cause rapid physiological arousal. (Hockenbury, 483) These glands are on top of the "kidneys." Catecholamines are released into the "blood" when a person is under physical or emotional “stress.” The main catecholamines are “dopamine,”  “norepinephrine,” and “epinephrine.” (PubMedHealth2)

Epinephrine: a hormone which contributes to "alertness." (SAM Oct/Nov 2007, 61) Secreted by the adrenal glands. (Brooker, G-13) A hormone and “neurotransmitter.” (NCIt) Used in “asthma” and “cardiac” failure and to delay absorption of local “anesthetics.” (MeSH) Also referred to as ‘adrenaline.’

Estrogen: female hormone. The rise in estrogen in pubescent girls gives them fuller lips. Causes the growth of the breasts and buttocks. (Eagleman, 90) Stimulates the female reproductive organs, and the development of secondary female sex characteristics. (MeSH) Can also be made in the laboratory. They may be used as a type of birth control and to treat symptoms of ‘menopause,’  “menstrual” disorders, “osteoporosis,” and other conditions. (NCIt)

Growth Hormone:  a “protein” made by the “pituitary gland” that helps control body growth and the use of "glucose" and "fat" in the body. (NCIt) Growth hormone stimulates “mitosis,” "cell differentiation” and cell growth. “Species” specific growth hormones have been synthesized. (MeSH) Also referred to as ‘somatotrophin.’

Insulin: a protein hormone secreted by 'beta' cells of the "pancreas." Plays a major role in the regulation of glucose “metabolism,” generally promoting the cellular utilization of glucose. It is also an important regulator of protein and "lipid" metabolism. Insulin is used as a drug to control insulin-dependent "diabetes mellitus." (UMLS) One of many hormones that helps the body turn the food we eat into "energy." Also, insulin helps us store energy that we can use later. After we eat, insulin works by causing glucose to go from the blood into our body's cells to make fat, "sugar," and protein. When we need more energy between meals, insulin will help us use the fat, sugar, and protein that we have stored. This occurs whether we make our own insulin in the pancreas gland or take it by injection. (PubMedHealth2)  Its absence, or the inability of cells to recognize it, causes diabetes mellitus. (Lewis, 201)

Melatonin: a hormone produced by the “pineal glad” in darkness but not in bright light. Melatonin receptors in the brain, in a “nucleus” immediately above the “optic chiasm,” react to this hormone and synchronize the nucleus to the 24-hour day/night rhythm, thus informing the brain when it is day and when it is night. A derivative of “serotonin.” (OxfordMed) Melatonin helps control the body's sleep cycle, and is an “antioxidant.” It is also made in the laboratory and sold as a supplement. (NCIt) Found in animals and plants. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of sleep, “mood,” and “reproduction.” Melatonin is also an effective antioxidant. (MeSH)

Norepinephrine: a hormone manufactured by the “adrenal glands.” (Hockenbury 48) Found in plants and is used pharmacologically. (MeSH) Editor’s note - norepinephrine is also a neurotransmitter. Also referred to as 'noradrenaline.'

Oxytocin: a natural hormone secreted in the “hypothalamus” of a woman’s brain. (Fields, 257) Plays the role of ‘Cupid’ uniting mother and child in a the powerful maternal behavior of bonding to her offspring immediately after birth. (Fields, 258) Sometimes called the ‘commitment neuromodulator’ because it reinforces bonding. When mothers look at photos of their children, brain regions rich in oxytocin are activated. While dopamine induces excitement, oxytocin induces a calm, warm mood that increases tender feelings and attachment and may lead us to lower our guard. In an experiment when people sniffed oxytocin and then participated in a financial game, they were more prone to trust others with their money. Walter J. Freeman proposes that oxytocin melts down existing neuronal connections that underlie existing attachments, so new attachments can be formed. (Doidge, 119) The brain’s "love" hormone, normally released during orgasm (in both sexes), labor, and nursing. Linked by Ian McGregor to “ecstasy” use. McGregor found that taking the drug ecstasy activated oxytocin-containing "neurons" in the hypothalamus, the part of the brain that normally releases the hormone. (Discover, “Science and Islam,” 16)

Testosterone: male hormone. In boys produces a more prominent chin, a larger nose, and a fuller jaw. Encourages the growth of muscles and broad shoulders. (Eagleman, 90) A hormone made mainly in the “testes.” It is needed to develop and maintain male sex characteristics, such as facial hair, deep voice, and muscle growth. Testosterone may also be made in the laboratory and is used to treat certain medical conditions. (NCIt)

Thyroxine (T4): the chief hormone secreted by the "thyroid gland," which increases the metabolic rate and regulates growth and development in animals. (Oxford) A hormone that contains “iodine.” T4 increases the rate of “chemical reactions” in cells and helps control growth and development. T4 can also be made in the laboratory and is used to treat thyroid disorders. (NCIt)

Triodothyronine (T3): a thyroid hormone containing 3 iodine atoms generally synthesized from ‘levothyroxine,’ and has greater biological activity. T3 enters the cell and binds to nuclear thyroid hormone “receptors,” and the ‘hormone-receptor complex’ in turn triggers gene "expression” and produces proteins required in the regulation of cellular “respiration,”  ‘thermogenesis,’ cellular growth and differentiation, and (in the) metabolism of proteins, carbohydrates and lipids. T4 and T3 also possess “cardiac” stimulatory effect. (NCIt)

Vasopressin: a “pituitary” hormone in humans and other mammals which promotes the retention of water by the kidneys and, when given in large quantities, raises the "blood pressure." (Oxford) Produced in a region of the brain called the hypothalamus. It is then stored and released from the pituitary gland. (PubMedHealth2) Also, a “neuromodulator” released in male mammals when they become fathers. (Doidge, 119) This hormone can contract smooth muscle during (the birth process) and lactation. It is also involved in "cognition," "tolerance," adaptation and complex sexual and maternal behavior, as well as in the regulation of water excretion and "cardiovascular" functions. (NCIt)  Also referred to as 'antidiuretic hormone' and 'ADH.'