Chapter 16: The Endocrine System PDF - Professor Bortz - Moravian University

Chapter 16 The Endocrine System TOPIC: Structure, Function, Control & Hormone Action (16.1 - 16.5) Professor Bortz Moravian University BIOL 104 anger  Endocrine Organs * Basic location: hosutbody insteadofgroups the's EYE * Secrete horm...

Chapter 16 The Endocrine System TOPIC: Structure, Function, Control & Hormone Action (16.1 - 16.5) Professor Bortz Moravian University BIOL 104 anger  Endocrine Organs * Basic location: hosutbody insteadofgroups the's EYE * Secrete hormones -chemicalmessengers that travel aroundbody in blood or lymph filtrate ofblood that carries immunecells chemicals > chemical structure of hormone determines water solubility, method of transport, how long it lasts before it’s degraded, and the receptors it acts 19 upon  Hormone Classification Amino Acid Based Steroids lipid 1. Solubility? water soluble except 1. Synthesized from:cholesterol thyroidhormone 2. Crosses plasma membrane? 2. Solubility?lipidsoluble cannot 3. Binds to receptor: in plasma 3. Crosses plasma membrane? membrane yes 4. Binds to receptor:insidecell > triggers: insigecegpgygnmmesg.gg > directly activates:genes to rmegpefuugey initiateresponse L composed of lipidbilayer takes direct qq.fr ngn  Hormone Activation Mechanisms * hormones only activate target cells that have can have different effectson differenttargetofPP fceptors Hormones can produce changes by: 1. Opening or closing: ion channels changingthe membrane potential 2. Stimulating synthesis of:enzymes or other proteins 3. Activating or deactivating:enzymes 4. Inducing: secretion of various substances 5. Stimulating:mitosis OASIS  Stimuli Causing Hormone Release * synthesis and release of most hormones regulated by negative feedback; keeps blood hormone levels relatively constant ex: stimulus triggers secretion > hormone levels rise > desired effect on target organ > secretion inhibited > hormone levels drop due to binding to receptor 1. Humoral stimuli - simplest - changing levels of ions or nutrients in blood triggers hormone secretion; ex: parathyroid hormone (blood Ca2+) and insulin (blood glucose) fight or 2. Neural stimuli - sympathetic flightsystem stimulates adrenals to release nervous epinephrine or norepinephrine in response to stress 3. Hormonal stimuli - glands secrete hormones in response to secretion of 1 hormones by other glands; ex: hypothalamus > anterior pituitary gland > target endocrine organ/gland (core of endocrinology!!) 2 3 raisesBP HR  1 no mone 2 no gne offone  Hormone Activity 1. Binding to specific receptor triggers pre programmedresponse inside cell 2. Degree of target cell activation depends on: a.bloodlevels ofhormone hormone activity b. number of receptorsfor hormone receptors activity c. Affinity - strength ofbindingto * more high-affinity receptors causes: ecptffgppegrepon csmffngefbhntal.mg targeteffect 3. Up-regulation - low levels of hormones in blood causes target cells to 9K Mmb 8 ablereceptors 4. Down-regulation - high levels of hormones in blood causes target cells to *aucenumpgfaf.EE itigni8iñtnélevels Ierststeen prevents: number ofavailablereceptors  Hormone Activity 5. Two ways hormones can circulate in blood: carrier freely or bound protein to Iggy'indblood ex: lipid soluble hormones must be attached toplasmaproteins for transport 6. Hormones broken down by enzymes in: cells kidneysor liver then excreted target * half-life - bynaitiwa.net lanFn9YmioEschafe8oPetQ Ethnetatiatformthesnormone longerhalf hormones must bind to receptor in orderto exert effects ontarget cell Hormone Interaction with Target Cells 1. Permissiveness - one hormone needs asecondhormonetoexertfulleffects ex: reproductive hormones must interact with thyroid hormone to ensure proper and timely development of reproductive system without2ndhormone effectsarereduced 2. Synergism - two hormonesworktogetherontargetcelltoproduceamplified effects fulleffectfrom eachhormoneseparately ex: glucagon and epinephrine together produce 150% more glucose than one acting alone releasesstoredglucoseintoblood 3. Antagonism - one hormone opposestheactionofanother ex: insulin lowers blood glucose, glucagon raises it  Chapter 16 The Endocrine System TOPIC: Pituitary Gland (16.6) Thyroid & Parathyroid Glands (16.7 - 16.8) Professor Bortz Moravian University BIOL 104  Pituitary Gland (Hypophysis) Location: sella turcica of sphenoid bone * size and shape of pea; connected to hypothalamus by infundibulum (stalk) Section of organ Two major lobes: 1. Posterior - composed of neural tissue; secretes hormones sent from hypothalamus (neural connection between two called hypothalamic hypophyseal tract) neural pathway * not a true endocrine gland!! (stores hormones, but does not manufacture them) made in hypothalamus 2. Anterior - composed of glandular tissue; manufactures and releases hormones; vascular connection to hypothalamus but no neural connection allows fordelivery of hormones from hypothalamus  hormone 1 hormone 2 norms one 3 Posterior Pituitary Hormones Oxytocin ADH * see “Pituitary Hormones” Google Slides for more * nothing additional needed on this slide  Anterior Pituitary Hormones GH TSH ACTH FSH LH PRL * see “Pituitary Hormones” Google Slides for more * nothing additional needed on this slide Thyroid Gross Anatomy * Largest endocrine gland in body Location: anterior trachea inferior to larynx Y Basic description: butterfly shaped two lobes connected by isthmus  Effie Thyroid Histology * composed of hollow, spherical follicles Schrounded Follicular cells - cuboidal or squamous; form walls of follicles fY * follicles contain colloid sect theater Parafollicular cells - between follicles; secrete calcitonin in response to high levels of blood cast  21caiatonI humoral mechanism 1 7 5 1 Thyroid Regulation TRH - thyrotropin-releasing hormone 1 2 hormonal TSH - thyroid stimulating mechanism hormone 2 Thyroid hormone - body’s major metabolic hormone; as 3 levels rise, hypothalamus innib.jo and anterior pituitary are Eekte inhibited 3 TH TH T3 Thyroid TH T3 cell converted Thyroid Hormone 1. Major metabolic hormone; lipid soluble easilycrosses plasmamembrane 2. Consists of two iodine-containing hormones known as Tz T4 3. Follicles of thyroid gland secrete mostly Ty which is converted to Tz at target organs tissues actuallyaffgts 4. Effects:increases basal metabolic rate andbodyheat regulates tissue growth development maintainsblood pressure 5. Thyroid gland stores enough colloid to provide thyroid hormone for 2 3 months  posterior Parathyroid Gross Anatomy * tiny and posterior to thyroid * usually four but number and location can vary slightly * primary regulators of:blood calcium levels cartimportant for APtransmission muscle contraction and blood clotting PTH parathyroid hormone  Parathyroid Histology * Composed of larger oxyphil cells (function unknown) and smaller parathyroid cells (secrete PTH - parathyroid hormone) * PTH controls blood antagonist adf.gn.in * decreased blood Ca2+ levels:trigger PTHrelease stimulus response * increased blood Ca2+ levels: inhibit PTHrelease  PTH Release Mechanism PTH has three target organs: 1. Skeleton - stimulates osteoclasts to digest bonematrix releasing calcium and phosphate into blood 2. Kidneys - enhances reabsorption of calcium from urine back intoblood 3. Small Intestine - activates Vitamin D, which increases absorptionofcalcium from food cqfthkgsmkitmaab.to ption  Chapter 16 The Endocrine System TOPIC: Pituitary Hormones (Table 16.3)  Posterior Pituitary Hormones Hormone Release Target Organ & Effects Oxytocin In response to stretching of Uterus: stimulates contractions uterine cervix or suckling of infant Breast: initiates milk ejection at breast ADH In response to increased blood Kidneys: stimulates cells of kidney (Antidiuretic Hormone) solute or decreased blood volume tubule to reabsorb water from Inhibited by appropriate hydration urine back into blood stream initiation tfffty.pl or alcohol kidneys filter blood imitation leave  released Anterior Pituitary Hormones pothalamus Hormone Release Target Organ & Effects hormone hormone 3 GH In response to GHRH (growth All body cells, especially skeletal (Growth Hormone) hormone releasing hormone) muscle and bone secretion during sleep TSH In response to TRH (thyroid Thyroid gland: stimulates release (Thyroid Stimulating releasing hormone) secretion of thyroid hormones Hormone) ACTH In response to CRH Adrenals: stimulates release of (Adrenocorticotropic (corticotropin releasing glucocorticoids and androgens Hormone) hormone) secretion  GnRH ovaries testes different effects EH Anterior Pituitary Hormones Hormone Release Target Organ & Effects FSH In response to GnRH (gonadotropin Ovaries: ovarian follicle maturation (Follicle Stimulating releasing hormone) secretion and release of estrogen Hormone) Testes: stimulates sperm production LH In response to GnRH (gonadotropin Ovaries: ovulation and release of (Luteinizing Hormone) releasing hormone) secretion estrogen and progesterone Testes: release of testosterone PRL In response to decreased PIH Breasts: stimulates milk (Prolactin) (prolactin inhibiting hormone) production secretion P 11 inhibits PRL in males non lactating females of PIH whichtriggers Wendorff half pastproduce milk the secretion me itedat i Chapter 16 The Endocrine System TOPIC: Adrenals, Pineal Gland Pancreas and Gonads (16.9 - 16.11) Professor Bortz Moravian University BIOL 104  Adrenal Anatomy * paired organs on top of kidneys * encased in fibrous capsule and fat Medulla - central portion; part of Ahh sympathetic nervous system fightorflight Cortex - peripheral portion; makes up bulk of organ * medulla and cortex produce different hormones to mitigate stress  Adrenal Cortex cortex * produces corticosteroids (lipid soluble); g longer lasting response than hormones secreted by adrenal medulla Three zones: 1. Zona glomerulosa - produces mineralocorticoids 2. Zona fasciculata - produces classes glucocorticoids noramones 3. Zona reticularis - produces gonadocorticoids * more on upcoming slides  Mineralocorticoids Function: regulate electrolyte concentrations in blood particularly Nat Kt * Na+ concentration can influence: blood volume and blood pressure because1H20 attracted instant potentials * K+ concentration influences:the driveIps Aldosterone - primary regulator of Na+ and K+; targets kidney tubules to reabsorb Na+ into blood (increases blood volume/pressure) and secrete K+ into urine PEfenatsseatsecietifherefitZ.fi H2o follows * Can alter acid-base balance of blood due to: AP p * Effects brief (~20 min) for: continuous monitoring precise control * Secretion stimulated by: blood volume bloodpressure and blood K levels  inhibitor Aldosterone Secretion Regulation * four factors influence aldosterone secretion (#s 1 & 2 are most important) * ANP (#4) inhibits aldosterone release > lowers blood volume/blood pressure by eliminating Na+ and H2O in urine 899 9 a  Glucocorticoids glucose * influence metabolism and help us resist stressors glucose is necessary for ATP production * help keep: blood levels glucose stable maintain blood pressure Cortisol - primary glucocorticoid; converts fats and proteins to: glucose to produce ATP * causes vasoconstriction to: increase blood pressured vesseldiameter L which bloodpressure when volume Preegge  I Gonadocorticoids gonads * most are weak androgens (male sex hormones), which are converted to testosterone and some to estrogen * amount of gonadocorticoids produced by adrenal cortex much less than those producedby gonads Contribute to: 1. axillary pubic hair development 2. sex drive women 3. post menopausalestrogenproduction when estrogen is no longerproduced by ovaries  Adrenal Medulla * part of sympathetic nervous system fight or flight * synthesizes: epinephrine norepinephrine > contricts blood vessels raises blood pressure > dilates airways * very brief response; involved in fight or flight  Pineal Gland * tiny gland that hangs from:roof of 3rdventrical in diencephalonIntyp ÑaMa mus I epithalamus * secretes: melatonin makes sleepy you > lowest levels secreted: around noon > highest levels secreted: night morning cortisol secretion wakes you up > melatonin receptors in hypothalamus help regulate: sleep wake cycle biological clock  Pancreas Basic description: soft tadpole shaped Location: posterior78119Mach Function: both endocrine exocrine functions * composed mainly of acinar cells - secrete digestiveenzymes into small intestine  Pancreas Pancreatic islets - clusters of two cell types: 1. Alpha cells - fewer; secrete glucagon increasesblood glucose 2. Beta cells - more numerous; secrete insulin decreases bloodglucose Glucagon/Insulin Regulation Glucagon - breaksdown ytfgEE.im liver to release glucose into blood Insulin - transports glucose into body andmusclecells for storage * can be used to make: TP storedas glycogen of converted to fat  Gonads * Ovaries and testes produce same steroid sex hormones as adrenals, but in higher quantity Ovaries - produce ova (eggs), estrogen and progesterone (maturation of reproductive organs, appearance of secondary sex characteristics at puberty, regulation of menstrual cycle) Testes - produce sperm and testosterone (maturation of reproductive organs, appearance of secondary sex characteristics at puberty, sex drive, sperm production) Placenta - temporary endocrine organ; secretes estrogen, progesterone and hCG (human chorionic gonadotropin) to influence course of pregnancy