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Introduction to Endo 3
set 3
57
Science
Undergraduate 4
01/18/2009

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Term
Hormone Receptors
Definition
two types exist cell surface, nuclear receptor. Most hormone receptors are large proteins between 2-100 thousand/cell
Term
Hormone Action Mechanism
Definition
interacts with receptor, drives effect, also affects receptor
Term
Neurotrnsmitter action
Definition
change membrane permeability, act on receptor and related proteins to open or close an ion gate
Term
Metabolic/peptide hormone action
Definition
(insulin, GI hormones) activates adenylyl cyclase which carries on a downstream activity which carries out secondary effect specific to response
Term
Second Messenger
Definition
amplify signal. cAMP,cGMP, calcium, calmodulin, membrane phospholipid metabolites.
Term
cAMP messenger functions
Definition
involved in adrenocorticotropin, TSH, LH, FSH, ADH, PTH, glucagon, catecholamines, secretin, and hypothalamic releasing hormones. binds to inactive protein kinase A promoting dissociation.
Term
Calcium/Calmodulin function
Definition
calmodulin saturated with calcium activates myosin kinase (smooth muscle contraction).
Term
Membrane Phospholipid metabolites
Definition
activated phospholipase breaks down phosphatidyl inositol biphosphate into inositol triphophate and diacyl glycerol. ITP3 mobilizes calcium from mitochondria and ER,DAG activates protein kinase C involved in cell division. DAG supplies arachidonic acid precursor molecule
Term
Steroid Hormone mechanism of action
Definition
diffuses/tansported to nucleus=>binds DNA=>initiates transcription=>mRNA diffueses to cytoplasm to promote ribosomes to form protein.
Term
Thyroid Hormone Mechanism
Definition
thyroxine and triiodothyronine secreted by thyroid, enter multiple cell types, can bind hundreds of DNA sites, drive cellular function for days or weeks
Term
G-protein coupled receptors
Definition
guanonsine triphosphate binding proteins. adenylayte cyclase, Ca2+ calmodulin, inositol 1,4,5-triphosphate. 3 subunits a,B,G. bind GTP active form.
Term
G protein transducers
Definition
g proteins regulate activity of effector molecules resulting ultimately in biologic response. Identity of G proetin determined by alpha subunit which is responsible for effector activation.
Term
Effectors of G proteins
Definition
linked to G protein-coupled receptors. activation results in transient increase in intracellular cAMP levels.
Term
Regulation of G protein
Definition
activation of effectors by G-protein is subject to regulation that prevents overstimulation by an agonist.
Term
Adenylate Cyclase mechanism
Definition
binding-GDP replaced by GTP-G protein activates adenylate cyclase-Adenylat cyclase catalyses conversion of ATP to cAMP-cAMP activates protein kinase A, phosphorylates specific proteins, producing highly specific physiologic actions-cAMP degraded to 5'AMP by phosphodiesterase.
Term
Agonist
Definition
could be hormone or synthetic. bind to a receptor and transform into a response.
Term
Antagonist
Definition
bind receptor but does not transform into response.
Term
Partial Agonist/Partial Antagonist
Definition
partial agonist block binding of full agonist and suppress receptor activity to level of partial agonist
Term
Mixed Agonist/Antagonist
Definition
act in different ways through same receptor.
Term
Self-limiting responses
Definition
chronic stimulation of cells with peptide hormone can decrease the amounts of receptor that are expressed on cell surface.
Term
Protein Hormone synthesis
Definition
does not require special machinery. Growth Hormone, Prolactin, PTH produced similarly to other secreted proteins
Term
Peptide Hormones synthesis
Definition
produced by cleavage of a larger protein.
Term
Thyroid Hormone synthesis
Definition
produced by iodination and coupling of tyrosine residues of thymoglobulin
Term
Hormone production regulation
Definition
1. level of transcription 2. posttranslational mechanisms 3.level of release (hypothalamic-pituitary-target gland system and free-standing endocrince glands)
Term
Hypthalamic-pituitary-gland system
Definition
CNS-Hypothalamus-Pituitary-Peripheral gland which releases feedback control on hypothalamus and pituitary.
Term
Hormone Transport
Definition
steroids, thyroid hormones, Vit-D are bound to plasma proteins. Growth Hormone, IGF-I, IGF-2=>IGF binding proteins. Vasopressin Oxytocin bind neurophysisns.
Term
CBG
Definition
plasmas binding protein that binds cortisol and progesterone
Term
SHBG
Definition
plasma binding protein that binds testosterone and estradiol
Term
TBG
Definition
thyroid binding globulin
Term
Plasma Binding Proteins
Definition
binds to hormones that need transport non-covalently and increases hormone half-life in circulation
Term
Free Hormone
Definition
not bound. available for receptor binding, dictates feedback inhibition of hormone release, cleared from circulation, correlates best with clinical states of hormone excess and deficiency.
Term
Role of plasma binding protein
Definition
plasma protein prevents immediate uptake allowing it to travel to a distal tissue for uptake. Free hormone will be consumed in proximal tissue.
Term
Transport of hormones across membrane
Definition
many nuclear receptor ligands can enter and exit cells by transversing lipd bilayer. influx and efflux varies in different tissues and cell types. ex.) tyroid hormone
Term
Hormone Degradation
Definition
some proteins are glycosylated glycoproteins have half-lives of hours and need degradation. peptide hormones usually have shorter half-lives(minutes)
Term
Mechanism of Hormone Degradation
Definition
cell surface receptors and nonreceptor hormone-binding sites. Lysosome degrades hormones enzymatically.
Term
Thyroid Hormone degradation
Definition
degraded to inactive forms by deiodinases. Deaminations and decarboxylations of alanine side chains aid as well.
Term
Catecholamine degradation
Definition
very short half-life of 2 minutes. degraded by: catechol-O-methyltransferase(COMT) and Monoamine Oxidase (MAO).
Term
Prostaglandin degradation
Definition
are metabolized within seconds by enzymes as oxidation of teh 15-hydroxyl group that inactivates the prostaglandin.
Term
Recombinant DNA
Definition
this technology allows us to synthesize growth hormone, insulin, and polypeptide hormones.
Term
Neurosecretion
Definition
neurons that secrete hormones into circulation. Hypothalamus does this.
Term
Direct Autonomic innervation of Endocrine
Definition
couples CNS system signals to hormone release, innervations of adrenal medulla, parathyroid, pancreatic islets.
Term
Anterior Pituitary secretion control
Definition
hypthalamic, arcuate, periventricular, medial preoptic, paraventricular from median emmience. Hypophysial portal system.
Term
Anterior Pituitary Hormones
Definition
adrenocorticotropic, growth, prolactin, thyroid-stimulating, LH, FSH
Term
Posterior Pituitary Hormone
Definition
oxytocin, vasopressin(antidiuretic)
Term
Neurohypophysial Neurons
Definition
posterior pituitary vasopressin and oxytocin into general circulation
Term
Hypophysiotropic Neurons
Definition
of hypothalamus release hormones into hypothalamic-pituitary blood vessels, which deliver hormones to anterior pituitary.
Term
Stimulating Hormones
Definition
TRH, GnRH, GHRH, Prolactin-releasing factors
Term
Inhibiting hormones
Definition
somatostatin, dopamine
Term
Hypothalamus Products
Definition
bioactive amines, peptides, amino acids
Term
Substance P
Definition
stimulates prolactin and inhibits CRH-stimulated ACTH release.
Term
VIP
Definition
stimulates the release of several pituitary hormones, including prolactin, growth hormone, and ACTH
Term
Regulation of Anterior Pituitary
Definition
anterior pituitary release is usually regulated by vascular delivery of hypothalamic and peripheral hormones.
Term
3 patterns of anterior pituitary hormone release
Definition
spontaneous brain rhythms release LH and FSH, peripheral hormones regulate through feedback (corisol, thyroid, ACTH,TSH,LH), "Intervening factors", stress, nutritional influences, illness.
Term
Effects of stress
Definition
releases ACTH, GH, prolactin
Term
Systematic illness effects
Definition
suppress hypothalamic-pituitary-thyroid axis and release gonadotropins
Term
Hormones that stimulate ACTH release
Definition
Angiotensin II, Interleukin-2, cholecystokinin, oxytocin.
Term
Causes of CRH and ACTH release
Definition
interleukin-1, interleukin-2, and epinephrine.
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