Hormone

from old greek: ορμàν (horman) - to drive
German: Hormon

	Table of contents
	1. Definition 2. Homeostasis 3. Physiology 4. Hormones in detail 5. Background

Definition

Hormones are signalling and messaging molecules that ensure regulation of different body functions. They are secreted by hormone producing cells into surrounding tissue (paracrine delivery) or in blood vessels (classical endocrine delivery).

Homeostasis

Action of hormones originates from their binding to receptors that are located either in the cell membrane or in cytoplasm. After interaction with their target molecule they trigger in the cell a signalling cascade comprising different intracellular transmitters, e.g. second messengers.

Secretion of hormones is controlled by - often complex - regulation mechanisms on molecular level that are embedded in elaborate feedback control systems and frequently organised in antagonistic redundancy mechanisms. Temporally limited action of hormones is determined by their degradation, e.g. in target tissues, and measured as half life.

Physiology

In the human organism, hormones are produced either in single scatterd (disseminated) cells or in hormone-secreting tissues (endocrine glands).

Examples for endocrine glands are:

• Pituitary (Hypophysis)
• Thyroid
• Adrenal glands
• Islets of Langerhans in the Pancreas
• Testes and Ovaries

Although, many other tissues are apt to secrete hormones that act as tissue hormones.

Hormones in detail

• Eicosanoids
  • Leukotrienes
  • Prostaglandins
  • Prostacyclins
  • Thromboxanes
• Glycoprotein hormones
  • FSH
  • HCG (Beta-HCG)
  • HMG
  • LH
  • Thyrostimulin (TSH 2)
  • TSH (TSH 1)
• Catecholamines
  • Epinephrine
  • Dopamine
  • Metanephrine
  • Norepinephrine
  • Normetanephrine
• Classical thyroid hormones (iodothyronines)
  • 3,5-Diiodothyroinine (3,5-T2)
  • TETRAC
  • Thyroxine (T4)
  • TRIAC
  • Triiodthyronine (T3)
• Peptide hormones
  • Adiponectin
  • Antidiuretic hormone (Vasopressin, ADH)
  • Adrenomedullin
  • Agouti-Related Peptide (AGRP)
  • Angiotensin II (AII)
  • Atrial natriuretic peptide (ANP)
  • Bombesin
  • Calcitonin (CT)
  • CART
  • Cholecystokinin (CCK)
  • CRH
  • Enteroglucagon (GLI)
  • Erythropoietin (EPO)
  • Gastrin
  • Ghrelin
  • GHRH
  • Gastric inhibitory peptide (GIP)
  • Glucagon
  • GnRH
  • Hepcidin
  • HGH (GH, STH)
  • Homeostatic Thymus Hormone (HTH)
  • IGF 1
  • IGF 2
  • Inhibin
  • Insulin
  • Leptin
  • MCH
  • Melatonin
  • Motilin
  • Neuropeptid Y (NPY)
  • Natriuretic peptide Type B (BNP and Type C (CNP)
  • Neurotensin
  • Parathyroid hormone (PTH)
  • Omentin
  • Oxytocin
  • Pancreatic polypeptide (PP)
  • Peptide YY (PYY)
  • Prolactin (PRL)
  • Proopiomelanocortin (POMC) derivatives
    • Alpha-MSH
    • Beta-MSH
    • Gamma-MSH
    • CLIP
    • Endorphins
    • Enkephalins
    • Corticotropin (ACTH)
    • LPH
  • Relaxin
  • Resistin
  • Secretin
  • Somatostatin
  • Substance P
  • Thymosins
    • Thymosin Alpha-1
    • Thymosin Beta-4
  • Thymulin
  • TRH
  • Vasocactive intestinal peptide (VIP)
• Steroid hormones
  • Aldosterone
  • Androstendione
  • Corticosterone
  • Cortisol
  • Dihydrotestosterone (DHT)
  • DHEA and DHEAS
  • Estradiol (E2)
  • Estriol (E3)
  • Progesterone (P)
  • Testosterone (T)
• Steroid like hormones
  • 1,25-Dihydroxycholecalciferol
  • Cholecalciferol
• Other hormones
  • Cytokines and other locally acting hormones
• Hormone-like substances
  • Renin

Background

Endocrinology is the science and clinical speciality dealing with formation and regulation of hormones and with diagnosis and treatment of diseases that are caused by hormonal dysregulation.