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The endocrine system is the system of glands, each of which secretes different types of hormone directly into the bloodstream (some of which are transported along nerve tracts[citation needed]) to regulate the body. The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. It derives from the Greek words "endo" meaning inside, within, and "crinis" for secrete. The endocrine system is an information signal system like the nervous system, yet its effects and mechanism are classifiably different. The endocrine system's effects are slow to initiate, and prolonged in their response, lasting from a few hours up to weeks. The nervous system sends information very quickly, and responses are generally short lived. Hormones are substances (chemical mediators) released from endocrine tissue into the bloodstream where they travel to target tissue and generate a response. Hormones regulate various human functions, including metabolism, growth and development, tissue function, and mood. The field of study dealing with the endocrine system and its disorders is endocrinology, a branch of internal medicine. Features of endocrine glands are, in general, their ductless nature, their vascularity, and usually the presence of intracellular vacuoles or granules storing their hormones. In contrast, exocrine glands, such as salivary glands, sweat glands, and glands within the gastrointestinal tract, tend to be much less vascular and have ducts or a hollow lumen. In addition to the specialised endocrine organs mentioned above, many other organs that are part of other body systems, such as the kidney, liver, heart and gonads, have secondary endocrine functions. For example the kidney secretes endocrine hormones such as erythropoietin and renin. The endocrine system is made of a series of glands that produce chemicals called hormones. A number of glands that signal each other in sequence are usually referred to as an axis, for example, the hypothalamic-pituitary-adrenal axis. Contents [hide] 1 Endocrine organs and secreted hormones 1.1 Hypothalamus 1.2 Pineal body (epiphysis) 1.3 Pituitary gland (hypophysis) 1.3.1 Anterior pituitary lobe (adenohypophysis) 1.3.2 Posterior pituitary lobe (neurohypophysis) 1.4 Thyroid 1.5 Alimentary system 1.5.1 Stomach 1.5.2 Duodenum 1.5.3 Liver 1.5.4 Pancreas 1.6 Kidney 1.7 Adrenal glands 1.7.1 Adrenal cortex 1.7.2 Adrenal medulla 1.8 Reproductive 1.8.1 Testes 1.8.2 Ovarian follicle and corpus luteum 1.8.3 Placenta (when pregnant) 1.8.4 Uterus (when pregnant) 1.9 Calcium regulation 1.9.1 Parathyroid 1.9.2 Skin 1.10 Miscellaneous 1.10.1 Heart 1.10.2 Bone marrow 1.10.3 Adipose tissue 2 Major endocrine systems 3 Diseases 4 Other types of signaling 4.1 Autocrine 4.2 Paracrine 4.3 Juxtacrine 5 See also 6 References [edit]Endocrine organs and secreted hormones

Endocrine glands in the human head and neck and their hormones [edit]Hypothalamus Secreted hormone	Abbreviation	Produced by	Effect Thyrotropin-releasing hormone	TRH	Parvocellular neurosecretory neurons	Stimulate thyroid-stimulating hormone (TSH) released from anterior pituitary (primarily) Dopamine (Prolactin-inhibiting hormone)	DA or PIH	Dopamine neurons of the arcuate nucleus	Inhibit prolactin released from anterior pituitary Growth hormone-releasing hormone	GHRH	Neuroendocrine neurons of the Arcuate nucleus	Stimulate Growth hormone (GH) release from anterior pituitary Somatostatin (growth hormone-inhibiting hormone)	SS, GHIH, or SRIF	Neuroendocrine cells of the Periventricular nucleus	Inhibit Growth hormone (GH) release from anterior pituitary Inhibit thyroid-stimulating hormone (TSH) release from anterior pituitary Gonadotropin-releasing hormone	GnRH or LHRH	Neuroendocrine cells of the Preoptic area	Stimulate follicle-stimulating hormone (FSH) release from anterior pituitary Stimulate luteinizing hormone (LH) release from anterior pituitary Corticotropin-releasing hormone	CRH or CRF	Parvocellular neurosecretory neurons of the Paraventricular Nucleus	Stimulate adrenocorticotropic hormone (ACTH) release from anterior pituitary Oxytocin	OT or OXT	Magnocellular neurosecretory neurons of the Supraoptic nucleus and Paraventricular nucleus	Uterine contraction Lactation (letdown reflex) Vasopressin (antidiuretic hormone)	ADH or AVP or VP	Parvocellular neurosecretory neurons, Magnocellular neurosecretory neurons of the Paraventricular nucleus and Supraoptic nucleus	Increases water permeability in the distal convoluted tubule and collecting duct of nephrons, thus promoting water reabsorption and increasing blood volume [edit]Pineal body (epiphysis) Secreted hormone	From cells	Effect Melatonin	Pinealocytes	Antioxidant Monitors the circadian rhythm including inducement of drowsiness and lowering of the middle body temperature sleep cycle [edit]Pituitary gland (hypophysis) [edit]Anterior pituitary lobe (adenohypophysis) Secreted hormone	Abbreviation	From cells	Effect Growth hormone (somatotropin)	GH	Somatotrophs	Stimulates growth and cell reproduction Stimulates Insulin-like growth factor 1 release from liver Thyroid-stimulating hormone (thyrotropin)	TSH	Thyrotrophs	Stimulates thyroxine (T4) and triiodothyronine (T3) synthesis and release from thyroid gland Stimulates iodine absorption by thyroid gland Adrenocorticotropic hormone (corticotropin)	ACTH	Corticotrophs	Stimulates corticosteroid (glucocorticoid and mineralcorticoid) and androgen synthesis and release from adrenocortical cells Beta-endorphin	-	Corticotrophs	Inhibits perception of pain Follicle-stimulating hormone	FSH	Gonadotrophs	In females: Stimulates maturation of ovarian follicles in ovary In males: Stimulates maturation of seminiferous tubules In males: Stimulates spermatogenesis In males: Stimulates production of androgen-binding protein from Sertoli cells of the testes Luteinizing hormone	LH	Gonadotrophs	In females: Stimulates ovulation In females: Stimulates formation of corpus luteum In males: Stimulates testosterone synthesis from Leydig cells (interstitial cells) Prolactin	PRL	Lactotrophs	Stimulates milk synthesis and release from mammary glands Mediates sexual gratification Melanocyte-stimulating hormone	MSH	Melanotropes in the Pars intermedia of the Anterior Pituitary	Stimulates melanin synthesis and release from skin/hair melanocytes [edit]Posterior pituitary lobe (neurohypophysis) Secreted hormone	Abbreviation	From cells	Effect Oxytocin		Magnocellular neurosecretory cells	Uterine contraction Lactation (letdown reflex) Vasopressin (antidiuretic hormone)	ADH or AVP	Parvocellular neurosecretory neurons	Increases water permeability in the distal convoluted tubule and collecting duct of nephrons, thus promoting water reabsorption and increasing blood volume Oxytocin and anti-diuretic hormone are not secreted in the posterior lobe, merely stored. [edit]Thyroid Secreted hormone	Abbreviation	From cells	Effect Triiodothyronine	T3	Thyroid epithelial cell	(More potent form of thyroid hormone) Stimulates body oxygen and energy consumption, thereby increasing the basal metabolic rate Stimulates RNA polymerase I and II, thereby promoting protein synthesis Thyroxine (tetraiodothyronine)	T4	Thyroid epithelial cells	(Less active form of thyroid hormone) (Acts as a prohormone to triiodothyronine) Stimulates body oxygen and energy consumption, thereby increasing the basal metabolic rate Stimulates RNA polymerase I and II, thereby promoting protein synthesis Calcitonin		Parafollicular cells	Stimulates osteoblasts and thus bone construction Inhibits Ca2+ release from bone, thereby reducing blood Ca2+ [edit]Alimentary system

[edit]Stomach Secreted hormone	Abbreviation	From cells	Effect Gastrin (Primarily)		G cells	Secretion of gastric acid by parietal cells Ghrelin		P/D1 cells	Stimulate appetite, secretion of growth hormone from anterior pituitary gland Neuropeptide Y	NPY		increased food intake and decreased physical activity. It can be associated with obesity. Somatostatin		D cells	Suppress release of gastrin, cholecystokinin (CCK), secretin, motilin, vasoactive intestinal peptide (VIP), gastric inhibitory polypeptide (GIP), enteroglucagon Lowers rate of gastric emptying Reduces smooth muscle contractions and blood flow within the intestine.[1] Histamine		ECL cells	stimulate gastric acid secretion Endothelin		X cells	Smooth muscle contraction of stomach[2] [edit]Duodenum Secreted hormone	From cells	Effect Secretin	S cells	Secretion of bicarbonate from liver, pancreas and duodenal Brunner's glands Enhances effects of cholecystokinin Stops production of gastric juice Cholecystokinin	I cells	Release of digestive enzymes from pancreas Release of bile from gallbladder hunger suppressant [edit]Liver Secreted hormone	Abbreviation	From cells	Effect Insulin-like growth factor (or somatomedin) (Primarily)	IGF	Hepatocytes	insulin-like effects regulate cell growth and development Angiotensinogen and angiotensin		Hepatocytes	vasoconstriction release of aldosterone from adrenal cortex dipsogen. Thrombopoietin		Hepatocytes	stimulates megakaryocytes to produce platelets[3] [edit]Pancreas Secreted hormone	From cells	Effect Insulin (Primarily)	β Islet cells	Intake of glucose, glycogenesis and glycolysis in liver and muscle from blood intake of lipids and synthesis of triglycerides in adipocytes Other anabolic effects Glucagon (Also Primarily)	α Islet cells	glycogenolysis and gluconeogenesis in liver increases blood glucose level Somatostatin	δ Islet cells	Inhibit release of insulin[4] Inhibit release of glucagon[4] Suppress the exocrine secretory action of pancreas. Pancreatic polypeptide	PP cells	Self regulate the pancreas secretion activities and effect the hepatic glycogen levels. [edit]Kidney Secreted hormone	From cells	Effect Renin (Primarily)	Juxtaglomerular cells	Activates the renin-angiotensin system by producing angiotensin I of angiotensinogen Erythropoietin (EPO)	Extraglomerular mesangial cells	Stimulate erythrocyte production Calcitriol (1,25-dihydroxyvitamin D3)		Active form of vitamin D3 Increase absorption of calcium and phosphate from gastrointestinal tract and kidneys inhibit release of PTH Thrombopoietin		stimulates megakaryocytes to produce platelets[3] [edit]Adrenal glands [edit]Adrenal cortex Secreted hormone	From cells	Effect Glucocorticoids (chiefly cortisol)	zona fasciculata and zona reticularis cells	Stimulates gluconeogenesis Stimulates fat breakdown in adipose tissue Inhibits protein synthesis Inhibits glucose uptake in muscle and adipose tissue Inhibits immunological responses (immunosuppressive) Inhibits inflammatory responses (anti-inflammatory) Mineralocorticoids (chiefly aldosterone)	Zona glomerulosa cells	Stimulates active sodium reabsorption in kidneys Stimulates passive water reabsorption in kidneys, thus increasing blood volume and blood pressure Stimulates potassium and H+ secretion into nephron of kidney and subsequent excretion Androgens (including DHEA and testosterone)	Zona fasciculata and Zona reticularis cells	In males: Relatively small effect compared to androgens from testes In females: masculinizing effects [edit]Adrenal medulla Secreted hormone	From cells	Effect Adrenaline (epinephrine) (Primarily)	Chromaffin cells	Fight-or-flight response: Boost the supply of oxygen and glucose to the brain and muscles (by increasing heart rate and stroke volume, vasodilation, increasing catalysis of glycogen in liver, breakdown of lipids in fat cells) Dilate the pupils Suppress non-emergency bodily processes (e.g., digestion) Noradrenaline (norepinephrine)	Chromaffin cells	Fight-or-flight response: Boost the supply of oxygen and glucose to the brain and muscles (by increasing heart rate and stroke volume, vasoconstriction and increased blood pressure, breakdown of lipids in fat cells) Increase skeletal muscle readiness. Dopamine	Chromaffin cells	Increase heart rate and blood pressure Enkephalin	Chromaffin cells	Regulate pain [edit]Reproductive

[edit]Testes Secreted hormone	From cells	Effect Androgens (chiefly testosterone)	Leydig cells	Anabolic: growth of muscle mass and strength, increased bone density, growth and strength, Virilizing: maturation of sex organs, formation of scrotum, deepening of voice, growth of beard and axillary hair. Estradiol	Sertoli cells	Prevent apoptosis of germ cells[5] Inhibin	Sertoli cells	Inhibit production of FSH [edit]Ovarian follicle and corpus luteum Secreted hormone	From cells	Effect Progesterone	Granulosa cells, theca cells	Support pregnancy:[6] Convert endometrium to secretory stage Make cervical mucus thick and impenetrable to sperm. Inhibit immune response, e.g., towards the human embryo Decrease uterine smooth muscle contractility[6] Inhibit lactation Inhibit onset of labor. Other: Raise epidermal growth factor-1 levels Increase core temperature during ovulation[7] Reduce spasm and relax smooth muscle (widen bronchi and regulate mucus) Anti-inflammatory Reduce gall-bladder activity[8] Normalize blood clotting and vascular tone, zinc and copper levels, cell oxygen levels, and use of fat stores for energy Assist in thyroid function and bone growth by osteoblasts Increase resilience in bone, teeth, gums, joint, tendon, ligament, and skin Promote healing by regulating collagen Provide nerve function and healing by regulating myelin Prevent endometrial cancer by regulating effects of estrogen Androstenedione	Theca cells	Substrate for estrogen Estrogens (mainly estradiol)	Granulosa cells	Structural: Promote formation of female secondary sex characteristics Accelerate height growth Accelerate metabolism (burn fat) Reduce muscle mass Stimulate endometrial growth Increase uterine growth Maintain blood vessels and skin Reduce bone resorption, increase bone formation Protein synthesis: Increase hepatic production of binding proteins Coagulation: Increase circulating level of factors 2, 7, 9, 10, antithrombin III, plasminogen Increase platelet adhesiveness Increase HDL, triglyceride, height growth Decrease LDL, fat deposition Fluid balance: Regulate salt (sodium) and water retention Increase growth hormone Increase cortisol, SHBG Gastrointestinal tract: Reduce bowel motility Increase cholesterol in bile Melanin: Increase pheomelanin, reduce eumelanin Cancer: Support hormone-sensitive breast cancers[9] (Suppression of production in the body of estrogen is a treatment for these cancers.) Lung function: Promote lung function by supporting alveoli.[10] Inhibin	Granulosa cells	Inhibit production of FSH from anterior pituitary [edit]Placenta (when pregnant) Secreted hormone	Abbreviation	From cells	Effect Progesterone (Primarily)			Support pregnancy:[6] Inhibit immune response, towards the fetus. Decrease uterine smooth muscle contractility[6] Inhibit lactation Inhibit onset of labor. Support fetal production of adrenal mineralo- and glucosteroids. Other effects on mother similar to ovarian follicle-progesterone Estrogens (mainly Estriol) (Also Primarily)			Effects on mother similar to ovarian follicle estrogen Human chorionic gonadotropin	HCG	Syncytiotrophoblast	promote maintenance of corpus luteum during beginning of pregnancy Inhibit immune response, towards the human embryo. Human placental lactogen	HPL	Syncytiotrophoblast	increase production of insulin and IGF-1 increase insulin resistance and carbohydrate intolerance Inhibin		Fetal Trophoblasts	suppress FSH [edit]Uterus (when pregnant) Secreted hormone	Abbreviation	From cells	Effect Prolactin	PRL	Decidual cells	milk production in mammary glands Relaxin		Decidual cells	Unclear in humans and animals [edit]Calcium regulation Further information: Calcium metabolism

[edit]Parathyroid Secreted hormone	Abbreviation	From cells	Effect Parathyroid hormone	PTH	Parathyroid chief cell	Calcium: Stimulates Ca2+ release from bone, thereby increasing blood Ca2+ Stimulates osteoclasts, thus breaking down bone Stimulates Ca2+ reabsorption in kidney Stimulates activated vitamin D production in kidney

Phosphate: Stimulates PO3-4 release from bones, thereby increasing blood PO3-4. Inhibits PO3-4 reabsorption in kidney, so more PO3-4 is excreted Overall, small net drop in serum PO3-4. [edit]Skin Secreted hormone	From cells	Effect Calcidiol (25-hydroxyvitamin D3)		Inactive form of vitamin D3 [edit]Miscellaneous

[edit]Heart Secreted hormone	Abbreviation	From cells	Effect Atrial-natriuretic peptide	ANP	Cardiac myocytes	Reduce blood pressure by: reducing systemic vascular resistance, reducing blood water, sodium and fats Brain natriuretic peptide	BNP	Cardiac myocytes	(To a lesser degree than ANP) reduce blood pressure by: reducing systemic vascular resistance, reducing blood water, sodium and fats [edit]Bone marrow Secreted hormone	From cells	Effect Thrombopoietin	liver and kidney cells	stimulates megakaryocytes to produce platelets[3] [edit]Adipose tissue Secreted hormone	From cells	Effect Leptin (Primarily)	Adipocytes	decrease of appetite and increase of metabolism. Estrogens[11] (mainly Estrone)	Adipocytes [edit]Major endocrine systems

The human endocrine system consists of several systems that operate via feedback loops. Several important feedback systems are mediated via the hypothalamus and pituitary.[12] TRH - TSH - T3/T4 GnRH - LH/FSH - sex hormones CRH - ACTH - cortisol Renin - angiotensin - aldosterone [edit]Diseases

Disability-adjusted life year for endocrine disorders per 100,000 inhabitants in 2002.[13] no data less than 80 80-160 160-240  240-320  320-400  400-480  480-560  560-640  640-720  720-800  800-1000  more than 1000 Main article: Endocrine diseases Diseases of the endocrine system are common,[14] including conditions such as diabetes mellitus, thyroid disease, and obesity. Endocrine disease is characterized by disregulated hormone release (a productive pituitary adenoma), inappropriate response to signaling (hypothyroidism), lack of a gland (diabetes mellitus type 1, diminished erythropoiesis in chronic renal failure), or structural enlargement in a critical site such as the thyroid (toxic multinodular goitre). Hypofunction of endocrine glands can occur as a result of loss of reserve, hyposecretion, agenesis, atrophy, or active destruction. Hyperfunction can occur as a result of hypersecretion, loss of suppression, hyperplastic or neoplastic change, or hyperstimulation. Endocrinopathies are classified as primary, secondary, or tertiary. Primary endocrine disease inhibits the action of downstream glands. Secondary endocrine disease is indicative of a problem with the pituitary gland. Tertiary endocrine disease is associated with dysfunction of the hypothalamus and its releasing hormones.[citation needed] As the thyroid, and hormones have been implicated in signaling distant tissues to proliferate, for example, the estrogen receptor has been shown to be involved in certain breast cancers. Endocrine, paracrine, and autocrine signaling have all been implicated in proliferation, one of the required steps of oncogenesis.[15] [edit]Other types of signaling