Chapter 18 - Endocrine System- Lecture 1 PDF

Part 1: Introduction to the Endocrine System, Forms of Cell-to-Cell Communication, & 3 Classes of Hormones Part 2: General Overview of Endocrine Organs, and a Deep Look Into the Pancreas Part #1:  Compare and contrast the various communication methods, especially synaptic vs endocrine.  Identify a...

Part 1: Introduction to the Endocrine System, Forms of Cell-to-Cell Communication, & 3 Classes of Hormones Part 2: General Overview of Endocrine Organs, and a Deep Look Into the Pancreas Part #1:  Compare and contrast the various communication methods, especially synaptic vs endocrine.  Identify and describe the main organs and key terms associated with the endocrine system.  Define hormones and receptors, and compare and contrast the 3 classes of hormones and 2 locations of receptors.  Compare and contrast lipid soluble vs water soluble hormones and link this objective to the previous objective. Part #2:  Differentiate among the various endocrine organs and each of their big picture function.  Describe the pancreas, its big picture function, its histology, its 2 main cells, the hormones released by those cells, and the functions of those hormones.  Differentiate between Type 1 and Type 2 Diabetes and explain how each is related to the pancreas.     Regulates “long-term” processes via chemical signals known as? Hormones – bind to specific receptors between cells relaying information and instructions. An effector’s membrane protein that responds to signals ◦ Ex:Hormones, light, antigens, neurotransmitters, ions Main mechanisms of intercellular communic. ◦ Ex: Epithelial tissues Heart – intercalated disks     Paracrine w/in a tissue – “healing processes” ◦ EX: Eicosanoids Autocrine targets same cell – “WBC stimulation” ◦ Helper T-cell activation! Endocrine Comm. – targets distant tissues via bloodstream – “long-term homeostasis/changes” Neural/Synaptic Comm. – occurs w/in synapses via neurotransmitters – rapid communication that is short lived – “immediate + emergency responses”.  Endocrine Strength of Signal – based on conc. of hormones w/in blood. ◦ IE: many will be held w/in a specific range.  Neural/Synaptic Comm. Strength of Signal – based on frequency of neural signal   Chemical signals, travel in bloodstream, bind specific receptors of effector in a distance. Function: modify cellular activity of effector: ◦ Alter genetic activity – turn on/off ◦ Stimulates metabolic activity – cell more active. ◦ Change membrane permeability – allows entrance or release of substances – leads to cellular response! ◦ MP: Regulates long-term, complex processes  reproduction, digestion, chemical balance, energy levels. Hormones are divided into 3 classes: 1. Amino acid derivatives – tyrosine OR tryptophan 2. Peptide hormones – long chains of amino acids 3. Lipid derivatives – lipid soluble substances.  ◦ Freely pass cell membrane   Small molecules derived from an amino acid? 2 types of amino acid derivatives. AA1) Tyrosine derivatives : ◦ i) Thyroid hormones (lipid soluble) produced via thyroid gland = regulates metabolism of cells. ◦ ii) Catecholamines (water soluble) include:  I] nor- and epinephrine = fight and flight response  II] Dopamine = reward response as NT; many functions (several target cells) as hormone  AA2) Tryptophan (water soluble) derivatives: ◦ i) Melatonin – sleep hormone; regulates day-cycle. ◦ ii) Serotonin – mood enhancer + many others.  Short lived molecules survive minutes to hours         Longer lived hormones compared to AA derivatives, but are still “short-lived” – minutes, hours, days. Lipid Soluble or Water Soluble? WATER SOLUBLE – Meaning? Can’t by-pass cell membrane freely = Binds extracellular receptors. Often produced as prohormones ◦ inactive molecules converted to active hormones before or after secretion. Ex:pro-insulin Are the “primary messenger.” First molecule to start a chemical cascade that results in a response. Series of chemical changes that results in the final cellular response  Lipid messengers: 2 types (lipid soluble), meaning? ◦ Pass cell membrane and bind receptor INSIDE the cell  1) Steroid (MAIN) hormones aka “steroids” -? ◦ Derived from cholesterol; ◦ Long Lived – days to weeks ◦ Must be “bound” to protein when circulating.  2) Eicosanoids [I-coas-a-noids] derived from? ◦ arachidonic acid = 20 carbon fatty acid. ◦ Main function (MF) = paracrine signaling coordinating cellular activity w/in tissues (blood clotting) ◦ a) prostaglandins = regulates many cellular activities  Ex: blood clotting via vasoconstrictors/dilators. ◦ b) Leukotrienes = eicosanoids that stimulates inflammation  Ie: (PARACRINE SIGNALING).    Lipid messengers derived from cholesterol Circulate as “bound hormones” meaning? attached to transport proteins ◦ harder to breakdown; therefore, last longer in circul.  “Main Lipid soluble” hormones so far… ◦ Thyroid hormone & steroid hormones, which are Released by:  Reproductive organs (sex hormones), Adrenal Cortex of adrenal gland (aldosterone, cortisone, and androgens), and Kidneys (calcitriol). ◦ Non-polar molecules that can freely cross plasma membrane when NOT bound to a protein.  Polar hormones that CANNOT pass bi-layer, and therefore bind extracellular receptors. ◦ Receptors that bind hormones OUTSIDE the cell.  ALL PEPTIDE hormones  ALL Amino Acid derivatives except for Thyroid Hormone.  “Free Hormones” – not bound to transport proteins.  Non-polar hormones that freely pass bi-layer, and therefore bind intracellular receptors. ◦ Receptors inside the cells.  All steroid derivative hormones AND Thyroid hormone.  “Bound hormones” – must be attached to transport protein.  Students need to get in habit of categorizing each hormones and knowing “water or lipid-soluble”. Part 1: Introduction to the Endocrine System, Forms of Cell-to-Cell Communication, & 3 Classes of Hormones Part 2: General Overview of Endocrine Organs, and a Deep Look Into the Pancreas Part #1:  Compare and contrast the various communication methods, especially synaptic vs endocrine.  Identify and describe the main organs and key terms associated with the endocrine system.  Define hormones and receptors, and compare and contrast the 3 classes of hormones and 2 locations of receptors.  Compare and contrast lipid soluble vs water soluble hormones and link this objective to the previous objective. Part #2:  Differentiate among the various endocrine organs and each of their big picture function.  Describe the pancreas, its big picture function, its histology, its 2 main cells, the hormones released by those cells, and the functions of those hormones.  Differentiate between Type 1 and Type 2 Diabetes and explain how each is related to the pancreas.    Hypothalamus – Master endocrine gland; receives lots of sensory input and indirectly controls many organs. Pituitary Gland – 2nd in command; receives messages for hypo. and sends info out for slightly more direct control. Thyroid Gland – regulates NORMAL metabolism; important for development.        Adrenal Medulla – emergency metabolism via adrenaline (epi) Adrenal Cortex – salt balance + stress metabolic response. Pancreas – blood glucose regulation. Pineal Gland – sleep cycle regulation. Parathyroid – blood calcium regulation. Heart – reduce BP. Kidneys – produce RBCs + calcium regulation.      Inferior to stomach; superior to small intestine. Endocrine OR Exocrine organ? BOTH! Exocrine cells = pancreatic acini = 99% of pancreatic tissue volume – digestive enzymes. Endocrine cells = pancreatic islets – secrete insulin and glucagon – pancreatic hormones! Main Functions: 1) aid digestion via enzymes, 2) regulate blood glucose levels via insulin + glucagon!  aka islets of Langerhans. = produce hormones? ◦ Insulin and glucagon, function?  Peptide hormone produced by beta cells to lower blood glucose levels (BGLs). ◦ Secreted primarily during + shortly after meals. ◦ Target cells (liver + skeletal muscle) increase glucose and amino acid uptake, utilization, + ATP production. ◦ stim. glycogen, protein, and triglyceride formation.  MPs: Beta cells = insulin when BGLs rise = reduce BGLs = stim. cells to store energy reserves within liver + skeletal muscle.  Mobilizes energy reserves to maintain BGLs during fasting = secreted via alpha cells = insulin’s antagonist = increases BGLs.  Targets liver + skeletal muscle  Stimulates break down glycogen & triglycerides.  Can result in gluconeogenesis = glucose production via noncarbohydrate precursor.  Can you a) identify this histology slide as pancreas? b) distinguish islets vs acinar? c) name hormones secreted by organ? d) overall function of organ?   High BGLs due to faulty glucose metabolism. High levels of glucose in urine = glucosuria = indicator of diabetes. ◦ BGLs so high overwhelms kidney = fails to reabsorb.       2 types: Type I vs Type II? Insulin dependent = beta cells fail to produce functional insulin = 5 – 10% of cases likely genetic = requires injections/pump = often an autoimmune disease Most common = normal insulin, but receptor levels low or do not respond = insulin resistance Associated with obesity (diet related), treated via medication + exercise and dieting. Likely genetic related  High BGLs = exchange + blood flow complications.