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UNC-Chapel Hill BIOC 108 - 4.2 docx

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4.2 – Hormones3 Chemical Messenger Systems:1. Autocrine: chemical messenger is acting on the cell that released it2. Paracrine: ligands diffuse from one cell to the other, communicating 3. Endocrine: cell far away releases a messenger, which enters the circulatory system to find another cell (signaling at a distance)What do we need hormones for? Allow coordination of bodily function Signaling molecules: o Produced by glandso Transported by circulatory systemo Target distant organso Regulate physiology and behavior Centralized control of:o Blood sugar levelso Growtho Awake/sleep cycleso Reproductiono Fight or flight response Epinephrine and the Stress Response: Fight or flight response There is a neural stimulation at the brain And there is a pituitary-adrenal axis, which receives signal from brain  Causes epinephrine to be released and heart rate increases, breathing rate increases, and blood sugar increases Releases ACTH and cortisol hormone, liver releases glucose How does one cell relay information to another cell? - Within a cell, signals can diffuse within the membrane, or be actively transported - There is a Hydrophobic Plasma Membrane keeping the contents of the cell inside- 2 ways to emit a signal:1. Make a chemical messenger that is soluble in the plasma membrane (hydrophobic)2. Package the chemical messenger for exocytosis, storing signal in small vesicles, released outside of the cell- What about receiving the signal?o The hydrophobic chemical messenger will diffuse into the target cello The hydrophilic chemical messenger will require a protein receptor on the external surface of the cell to detect the messengerTypes of Hormones: Peptide: insulin and glucagon Amino Acid Derivative Steroid: derived from cholesterol, hydrophobic  Lipid: long carbon chains Types of Signal Receptors: Receptor Tyrosine Kinase: RTKo Insulin receptor o Human growth factor receptor G-Protein Coupled Receptor: o Beta Adrenergic Receptoro Glucagono Histamine Receptoro Serotonin Receptor Nuclear Receptor/Steroid Hormone Receptor:o Internal, in the cytoplasm of the cell, bind to steroid horomeso Estrogen receptoro Androgen receptoro Glucocorticoid receptor Hydrophobic Messengers: once signal crosses membrane, it binds to steroid receptor inside of the cell, steroid binds to this, moves into the nucleus where transcription and translation are occurring Steroid Hormones and Drugs: all derived from cholesterol, can move across membrane (hydrophobic) Cholesterol  Estrogen Testosterone  CortisoneHydrophilic Messengers: vesicles release signal across the membrane, cell receiving the signal has a receptor for the signal to bind to, this initiates a response inside the cell via a 2nd messengerG-Protein Coupled Receptor (GCPR) Signaling: Adenylate cyclase 2nd messenger Adenylate cyclase converts ATP to cAMP (2nd messenger for glucagon) Activates kinases which leads to cellular output Glucagon: - Maintains blood glucose during fasting, mobilizes fatty acids from adipose- Glycogen phosphorylase breaks down glycogen, turned on with phosphorylated- Glycogen synthase makes glycogen, turned off when phosphorylated- Signal = low blood glucose levels- G protein is activated, increased in cAMP = second messenger- Activates protein kinases- Proteins are phosphorylatedInsulin:- Receptor tyrosine kinase- 2nd messenger is activated with phosphorylation- Activates protein phosphatase- Reverses glucagon effectsG-Protein Coupled Receptor Signaling: Phospholipase C 2nd Messenger System- Phospholipicase c cuts head off of PIP 2 to get IP3 and DAGChemical Messengers and Drugs: Chemical messengers control and coordinate organ function This makes chemical messenger pathways the target of the majority of drugs  Agonist: something that promotes/activates the normal activity of a pathway Antagonist: something that inhibits the normal activity Albuterol: an agonist of the beta-adrenergic receptor Normal ligand is epinephrine or adrenalineZyrtec: an antagonist of the histamine receptors, block histamine from binding, therefore stopping the allergic reactionFlonase: a steroidal anti-inflammatory, glucocorticoid receptor agonist Ibuprofen: NSAID, non-steroidal anti-inflammatory drug, inhibits COX production Caffeine: an antagonist of adenosine receptors in neurons, blocks adenosine from binding, therefore stopping pro-sleep signaling, inhibitor of cAMP


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