A given hormone usually affects only a limited number of cells, which are called target cells.
A target cell responds to a hormone because it bears receptors for the hormone. In other words, a particular cell is a target cell for a hormone if it contains functional receptors for that hormone, and cells which do not have such a receptor cannot be influenced directly by that hormone. Hormones are chemical messengers secreted into blood or extracellular fluid by one cell that affect the functioning of other cells. Most hormones circulate in blood, coming into contact with essentially all cells. However, a given hormone usually affects only a limited number of cells, which are called target cells. 1 Once inside a target cell, the hormone (pink) binds to a receptor (purple) - similar to a hand sliding in a glove or mitten-and forms what is known as a hormone-receptor complex between the ligand and receptor. 2  A ligand is any molecule that binds to a specific site on a protein or other molecule. 1 A ligand is any molecule that binds to a specific site on a protein or other molecule. 2  In this case, the estrogen hormone 17-beta-estradiol is the ligand, and the estrogen receptor is the protein. Hormone receptors are found either exposed on the surface of the cell or within the cell, depending on the type of hormone. In very basic terms, binding of hormone to receptor triggers a cascade of reactions within the cell that affects function. Additional details about receptor structure and function are provided in the section on hormone mechanism of action. Hormones are chemical messengers secreted into blood or extracellular fluid by one cell that affect the functioning of other cells. Most hormones circulate in blood, coming into contact with essentially all cells. However, a given hormone usually affects only a limited number of cells, which are called target cells. A pheochromocytoma is a tumor that usually arises in the adrenal medulla and the patient presents with signs and symptoms of excessive production of catecholamines. MIBG Scan. Additional studies that are available for localizing a pheochromocytoma include the MIBG scan and octreotide scan. MIBG scans is used to detect adrenal pheochromocytoma. This test does not detect any other type of adrenal tumor. This is a radioisotope study in which a substance that is required by the adrenal gland to manufacture adrenaline is labeled with a radioactive isotope Receptors for peptide hormones tend to be found on the plasma membrane of cells, whereas receptors for lipid-soluble hormones are usually found within the cytoplasm. Upon hormone binding, the receptor can initiate multiple signaling pathways which ultimately lead to changes in the behaviour of the target cells. Steroid hormone receptors and related receptors are generally soluble proteins that function through gene activation. Their response elements are DNA sequences (promoters) that are bound by the complex of the steroid bound to its receptor. The receptors themselves are zinc-finger proteins. Whether a hormone binds to a receptor inside or outside a cell depends on the chemical nature of the hormone and its compatibility with the cell’s fatty outer membrane. The membrane’s fat layers impede water-friendly hormones from passing through but allow fat-derived hormones to readily enter the cell. 1 A ligand is any molecule that binds to a specific site on a protein or other molecule. 2  In this case, the estrogen hormone 17-beta-estradiol is the ligand, and the estrogen receptor is the protein. Benzodiazepines do not bind to the same receptor site on the protein complex as the endogenous ligand GABA (whose binding site is located between α- and β-subunits), but bind to distinct benzodiazepine binding sites situated at the interface between the α- and γ-subunits of α- and γ-subunit containing GABA A receptors. Bottom: view of the receptor from the extracellular face of the membrane. The subunits are labeled according to the GABA A nomenclature and the approximate locations of the GABA and benzodiazepine (BZ) binding sites are noted (between the α- and β-subunits and between the α- and γ-subunits respectively). Hormones, though, only bind to certain, compatible receptor types. Thyroid hormones and each steroid hormone group-the estrogens, androgens, progestins, glucocorticoids (stress hormones), and mineralocorticoids (water and ion-regulating hormones) - have a matching hormone receptor type. 1 A ligand is any molecule that binds to a specific site on a protein or other molecule. 2  In this case, the estrogen hormone 17-beta-estradiol is the ligand, and the estrogen receptor is the protein.
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/basics/hormones.html http://e.hormone.tulane.edu/learning/docking-receptor-binding.html http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/basics/hormones.html http://www.surgery.usc.edu/divisions/tumor/pancreasdiseases/web%20pages/Endocrine%20tumors/adrenal/pheochromocytoma.html https://en.wikipedia.org/wiki/Hormone_receptor http://e.hormone.tulane.edu/learning/docking-receptor-binding.html https://en.wikipedia.org/wiki/GABAA_receptor http://e.hormone.tulane.edu/learning/docking-receptor-binding.html
what receptor does MIBG target