Please note that this is a much-simplified view of a very complex system for which even minute changes in the chemical balance can cause very serious changes in the body.
"Hormones, always in astoundingly small quantities usually weighed in millionths of grams, often start reaction chains that influence the entire future course of the life process.
They serve not as the building stones but rather as executive officers, organizing and directing growth, differentiation and maintenance of organisms by control over enzymatic chemical transformations.
Their importance becomes most evident in their failures, under pathologic conditions and in senescence." (Encyclopaedia Britannica)
Hormones are Chemical Messengers synthesized and secreted in small amounts into blood or lymph vessels by the Endocrine glands, which effect the functions of the body’s cells and organs. Their usual chemical classification is into AMINES (e.g. Noradrenaline, Thyroxine),PEPTIDES (e.g. Oxytocin), PROTEINS (e.g. Insulin) and STEROIDS (e.g. Aldosterone, Testosterone). They are usually carried by the blood to bind to specific protein receptors within or on target cells some distance away. Hormone-receptor binding triggers a series of events within the cell, culminating in a cellular response (such as contraction or secretion). Some disorders (e.g. Diabetes insipidus, insulin resistance) are due to the absence or abnormality of Receptor sites.
AMINES are organic compounds derived from ammonia by the substitution of the hydrogen atoms by one, (PRIMARY), two (SECONDARY) or three (TERTIARY) alkyl groups. They are basic compounds with pH about 9.
About 24 amino acids are involved in protein synthesis and 10 of these cannot be made by the human body. They must therefore form an essential part of the diet as ESSENTIAL AMINO ACIDS.
All except the simplest GLYCINE are CHIRAL and include ALANINE, PHENYLANINE, GLUTAMIC ACID, CYSTEINE and HISTIDINE.
PEPTIDES are Molecules obtained by the partial hydrolysis of proteins, a short chain (OLIGOMER) of, AMINO ACIDS. Longer polymers (over 50 amino acids) are called POLYPEPTIDES or PROTEINS.
The amide linkage in proteins is known as the PEPTIDE LINKAGE. (An OLIGOMER is a small polymer consisting of three to ten monomer units, examples of which are OLIGOPEPTIDES and OLIGOSACCHARIDES)
A PROTEIN is one of the three essential types of energy feeds. It is a natural condensation polymer of amino acids occurring mainly as structural tissue in animals but also as enzymes in both animals and plants. Nearly all proteins are derived from 20 amino acids and include water-soluble globular proteins such as haemoglobin.
The ADRENOCORTICOTROPHIC Hormone (ACTH) also known as CORTICOTROPHIN is a chemical substance (PEPTIDE) produced in the front lobe of the PITUITARY gland. It stimulates the synthesis and release of GLUCOCORTICOIDS from the Adrenal Cortex, and is released in response to physical, emotional or chemical stress through a releasing factor produced in the HYPOTHALAMUS.
The ANTIDIURETIC HORMONE (ADH) also known as VASOPRESSIN is a chemical substance (PEPTIDE) manufactured in the hypothalamus but stored and released from the back part of the PITUITARY GLAND. It is one of the most fundamental hormones, being instrumental in conserving body fluids and has known effects en memory, circadian rhythm (daily biological periodicity e.g. sleep cycle, breathing, rise and fall of CORTISOL production controlled by the brain), and the control of blood pressure in the brain.
An absence or inadequate production of the antidiuretic hormone may cause diabetes insipidus, which is an uncommon disorder in which a large volume of dilute urine is produced daily, independently of the volume of fluid ingested. It may also be caused by chemical imbalance such as potassium depletion.
The FOLLICLE-STIMULATING Hormone (FSH) is a chemical substance (a GLYCOPROTEIN GONADOTROPHIN) secreted by the front lobe of the Pituitary gland. In Females it stimulates the early maturation of ovarian follicles and in Males the production of sperm.
The GROWTH Hormone (GH) also known as SOMATOTROPHIN or SOMATOTROPHIC Hormone is a POLYPEPTIDE, which is secreted by the front lobe of the Pituitary gland and effects protein, carbohydrate and lipid metabolism. Any abnormal secretion may result in abnormal enlargement or underdevelopment of skeletal features.
Small PEPTIDE factors such as EPIDERMAL GROWTH FACTOR (EGH) and PLATELET-DERIVED GROWTH FACTOR (PDEF) produced by certain cells have growth promoting effects on other specific types of cell when released. They nay play a role in some CANCERS.
The LUTEINZING Hormone (LH) is a GLYCOPROTEIN, a gonadotrophic hormone secreted by the front lobe of the Pituitary gland. In females it is involved in the final maturation of ovarian follicles, the process of ovulation and the initial formation of the CORPUS LUTEUM. In males it is known as the INTERSTITIAL CELL-STIMULATING Hormone (ICSH), which stimulates the interstitial (Leydig) cells of the testes to secrete testosterone.
The MELANOCYTE-STIMULATING Hormone (MSH) also known as INTERMEDIN is a POLYYPEPTIDE hormone present in the intermediate lobe of the Pituitary gland. It stimulates the synthesis and dispersion of MELANINS, which give, in different concentrations, the coloration (shades of yellow and brown) to the eyes, skin and hair.
In humans they may help protect the skin against the damaging effects of sunlight ultra-violet radiation.
Amounts present in skin depend on both genetic and environmental factors. An over-growth of the melanin-producing cells in the basal layer of the skin can cause a pigmented tumour or MELONOMA, which may become malignant and spread to other parts of the body.
Incidents have increased rapidly in recent years.
The PARATHYROID Hormone also known as PARATHORMONE is a POLYPEPTIDE synthesized and released by the chief cells of the parathyroid glands and released in response to lowered blood calcium levels. It has the opposite effect to CALCITONIN and raises the calcium level by stimulating the removal of calcium from bone and from the renal tubule into the blood, and it promotes the conversion of Vitamin D to an active form, which stimulates intestinal calcium absorption.
CALCITONIN, also called THYROCALCITONIN, is a POLYPEPTIDE Hormone secreted by "C" cells in the Thyroid gland and released in response to elevated blood calcium levels, lowering extracellular calcium levels.
The PARATHYROID glands are usually a set of four glands closely associated with the back of the thyroid gland within its capsule. Each cell consists of CHIEF cells, which produce parathyroid hormone and OXYPHIL cells whose function is unknown. lf the parathyroid glands are removed death follows within a few days.
The PARATHYROID Hormone is another in the peptide group which, with calcitonin, controls the calcium level in the blood. If the levels are inadequate to provide the proper ratio of phosphorus to calcium then the hormones trigger a process that removes minerals from the bones. Many pesticides interfere with the calcium transport system and since the body depends on natural organophosphates for life OP pesticides which act at the phosphorus atom may well cause imbalance in the blood levels.
The RELEASING Hormone is one of a group of hormones produced in the HYPOTHALAMUS and released by the neurones of the median eminence of the hypothalamus in response to stimuli from the brain. It is transported to the front lobe of the PITUITARY gland, where it stimulates or inhibits the release of a specific pituitary hormone (e.g. growth-hormone-releasing hormone), Previously known as a. releasing factor this tern is new confined to hypothalamic hormones whose chemical structures are unknown (e.g. prolactin-releasing factor). DOPAMINE promotes the release of growth hormone from the pituitary gland.
The SEX Hormones are STEROID hormones produced. and secreted mainly by the gonads and also by the ADRENAL glands, necessary for sexual development and the control of reproductive function.
The most important are certain androgens (TESTOSTERONE and DIHYDROTESTOSTERONE) found predominantly in males and PROGESTOGENS (PROGESTERONE) and certain OESTROGENS (DESTRADIOL, DESTRONE and.OESTRIOL) predominantly in females.
They probably act on the brain to influence sexual and other behaviour.
SECOND MESSENGER is a term used to describe INTERMEDIATE FACTORS (e.g. NUCLEOTIDES, PHOSPHOLIPIDS and CALCIUM IONS) present within the cell wall or interior. When activated by a variety of neurotransmitters or hormones (the FIRST MESSENGERS) they initiate a sequence of events leading ultimately to a cellular response (such as contraction, relaxation, secretion, or change in electrical activity)
STEROIDS are natural products including many HORMONES, BILE ACIDS, and the STEROLS, derived from the non-glyceride portion of fats, the best known of which is CHOLESTEROL. The molecule contains the CYCLOPENTANO-PERHYDROPHENANTHRENE NUCLEUS. Steroids are responsible for maintaining many vital functions, including sexual characteristics, salt and water balance, and muscle and bone mass.
ANDROGENS are usually sex hormones which induce masculine characteristics. They include TESTOSTERONE which may he converted to DIHYDROTESTERONE by such target organs as the PROSTATE gland. Androgens are necessary for the development of male genitalia in the foetus and the secondary characteristics (growth of penis and testes, pubic, facial and body hair, increased muscle strength and deepening voice) and in adults the production of sperm and maintenance of libido.
Small amounts are present in women.
LECITHIN is a phospholipid that forms part of bile and is involved in the break down of CHOLESTEROL which forms the hormones.
CHOLESTEROL is the most abundant steroid and is an essential component of plasma membranes, and the substance from which BILE SALTS and the ADRENO-CORTICAL and SEX HORMONES are formed. It is ingested in the diet as a constituent of egg yoke, meats (particularly offal) and some shellfish and is transported in the blood and synthesized in the liver, gastro-intestinal tract and other tissues. It is implicated in the cause of atherosclerosis (deposition of cholesterol and triglycerides on the inner arterial wall)
CORTICOSTEROIDS are steroid hormones secreted by the Adrenal Glands and include HYDROCORTISONE, CORTICOSTERONE and ALDOSTERONE. Their effects are numerous influencing metabolism, salt and water balance, and the function of many organs. Synthetic corticosteroids (eg cortisol and prednisolone) are use to treat a aide range of diseases including arthritis and cancer.
CORTISOL also known as HYDROCORTISONE is found in the Adrenal Cortex and is the major GLUCOCORTICOID hormone. It promotes the conversion of protein and fat into GLUCOSE (gluconeogenesis) and has an important role in the body’s resistance to physical and psychological stress, especially after trauma. Its synthesis and release is controlled by ADRENOCOTICOTROPHIC hormone. GLUCOCORTICOIDS are steroid hormones synthesized and released from the Adrenal cortex, important in carbohydrate metabolism and resistance of body to stress.' They include CORTISOL (HYDROCORTISONE),
CORTICOSTERONE and CORTISONE. They are used in replacement therapy as in ADDISONS DISEASE and to suppress inflammatory and allergic disorders.
Corticosterone and ALDERSTERONE have numerous effects on the metabolism, the salt and water balance and the function of many organs.
Synthetic corticosteroids are used to treat a variety of diseases including arthritis and cancer.
MINERALOCORTICOIDS are steroid hormones (mainly ALDOSTERONE) synthesised and released from the Adrenal Cortex and are important in the body’s Sodium and Potassium balance and the maintenance of extracellular fluid volume.
OESTROGEN is a steroid SEX Hormone produced in the Ovary, Placenta, Testis and Adrenal Cortex. They are responsible for the development of the female secondary sexual characteristics as well as promoting sexual readiness and preparing the uterus for implantation. They are used in contraceptives and in the treatment of cancers such as that of the prostate. They are also found in plants.
PROGESTERONE is a steroid hormone found in both sexes and is critical for the establishment and maintenance of pregnancy. It is primarily secreted by the ovaries and placenta and acts to prepare the uterus for implantation of the embryo. It inhibits ovulation during pregnancy and prepares the breasts for lactation. It also acts to raise body temperature.
TESTOSTERONE is the male sex hormone produced in the testes and is responsible for the development of the primary sex organs, secondary sexual characteristics and sexual behaviour.
SEROTONIN, also known as 5-DIHYDROXYTRYPTAMINE (5-HT), is a MONOAMINE widely distributed in blood, brain, and certain gut cells and is synthesized from the amino-acid TRYPTOPHAN.
It is important in Haemostasis and is probably a neurotransmitter in the Central Nervous System. It is involved with controlling bleeding, in sleep, mood, prolactin secretion and circadian rhythms, neurotransmission in the Central Nervous System and other important functions.
PARACRINE is a chemical messenger (e.g. PROSTAGLANDINS, PANCREATIC SOMATOSTATIN, KININS), which are produced by specific cells for transport to adjacent cells where it has a regulatory effect. It is rapidly inactivated by local enzymes. It may function as a hormone, neurohormone or as a neurotransmitter anywhere in the body.
ADRENALINE also known as EPINEPHRINE (in USA) is a hormone released by the ADRENAL MEDULLA in response to stress and in some other circumstances. It increases Heart Rate, raises blood pressure, and causes release of sugar into the blood from LIVER stores preparing the body for the FIGHT OR FLIGHT REACTION.
It may also he a neurotransmitter for the brain with many functions including cardiovascular and respiratory responses. Used therapeutically in acute asthma, heart attack and severe allergic responses.
The ADRENAL GLANDS also known as the SUPRARENAL GLANDS are found above the kidneys and comprise an outer cortex and inner medulla. The Cortex consists of three zones, which produce specific steroid hormones. The Outer zone produces mineralocorticoids (eg ALDOSTERONE) while the intermediate and inner zones produce glucocorticoids (eg CORTISOL) and sex hormones (ANDROGENS, OESTROGENS, and PROGESTAGENS). The medulla secretes a specific CATECHOLAMINE (either adrenaline or noradrenaline).
CATECHOLAMINES are biologically important chemicals (DOPAMINE, NORADRENALINE and ADRENALINE), which are all important to the Sympathetic and Central Nervous Systems. They are crucial to the control of Blood Pressure and in the “flight or fight response”.
Note that "Syndromes of depression may be a associated with a partial or absolute deficit of catecholamines, especially norepinephrine, in functionally important zones of the brain. In contrast, in some manic conditions, an excess of catecholamines is found. (Hormones. From molecules to disease. Baulieu & Kelly 1990)
VASOPRESIN is a peptide which helps control body fluids, breathing and blood pressure in the brain amongst other important functions. It is also known as ANTIDIURETIC HORMONE (ADH) and if this is absent or at inadequate levels diabetes may result.
SECRETIN stimulates the excretion of bile and intestinal secretions which aid fat digestion and has been beneficial in the treatment of Autism.
CHOLECYSTOKININ is involved in both triggering the feeling of satiety after eating and in the reactions to fear.
GASTRIN is not only secreted in response to alcohol and proteins in the gut but it also controls the sphincter muscles that prevent the stomach contents rising in the throat. If this substance is inhibited then the individual will suffer with rising acid, which can damage the teeth and cause cancer of the oesophagus.
Endocrine system disrupting chemicals are extremely dangerous. They should never, ever, have been allowed as food additives or released into the Environment.
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