Notes on Endocrine System and Hormone Producing Structures
Notes on Endocrine System and Hormone Producing Structures Biol 2230-001
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This 15 page Class Notes was uploaded by Madeline Notetaker on Monday January 25, 2016. The Class Notes belongs to Biol 2230-001 at Clemson University taught by Dr. John Cummings in Spring 2016. Since its upload, it has received 38 views. For similar materials see Human Anatomy & Physiology II in Biological Sciences at Clemson University.
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Date Created: 01/25/16
Endocrine Syslem Ac rivi ry Con rrolling Mechanisms Nervous system Ac riva re exci rable Tissue Muscles glands Eleclrochemical impulse STress is applied responds rapidly Shorl lived response Can adapl Endocrine system Ac riva re larger cell Possess recep ror for hormone Chemical messenger Hormone Secre red in ro bloods rream and Travels rhough body Only slimulale cells wilh specific recep ror Lag lime delay Seconds or days Response las rs longer Glands Exoc ne Produce secre rions rhal are not hormones No r parl of endocrine sys rem Ex swea r salivary diges rive enzymes Ducl Endoc ne Produce hormones Duc rless Secre res on ro surface and picked up by bloods rream Highly vascularized Chemical Messengers Hormones Chemical Thai is produced in one parl of body bu r has effec r somewhere else Long dislance chemical messenger Autocrines Chemical produced by cell rhal changes ac rivily of Thai cell Very Specific chemical Pardcrines Chemical secre red by cells rhal effec r neighboring cells in Thai area Local signal Pheromones Chemical rha r al rers behavior of ano rher individual Ex marllting rerri rory ma re a r rrac rion Hormone Classificalions Amino acid based Derivative of amino acids Water soluble Cannot diffuse across plasma membrane Majority of hormones in body non steroids Steroid based Derivative of cholesterol Fat soluble Can diffuse across plasma membrane by itself Only produced by gonads or cortex of adrenal gland Eicosanoid Biologically active lipid that has localized effect so not truly a hormone Prostaglandins and leulltotrienes Hormone Action Target cells Hormone only has effect on cells that has specific receptors General Hormone Actions Open or close ion channels Change permeability of cell Allows changes in ion flow Stimulate protein synthesis Cause cells to start producing proteins Structural or functional Activate or deactivate enzymes Turn on or shut off Change activity of existing proteins Promote secretion Mucous another hormone Stimulate mitosis Cause to start dividing Cell replication and growth Hormonal Mechanisms HOW WORK Amino acidbased Receptors on plasma membrane Because cant pass through lnvolves G proteins and secondary messengers Steroid based Receptors inside cell Often in nucleus Direct activation Specifically production of new proteins Steroid Action process Hormone diffuses through plasma membrane Binds with intracellular receptor if cell has one Activated complex binds to second receptor protein on DNA inside nucleus Transcription initiated mRNA translated moves out and finds ribosome Proteins produced for export Non steroid Action Cyclic AMP mechanism Cyclic AMP is secondary messenger PIP calcium mechanism PIP and calcium Cyclic AMP Mechanism Hormone binds to membrane receptor Modified receptor binds with G protein G protein is activated Activated G protein activates adenylate cyclase enzyme Adenylate cyclase generates cAMP from ATP cAMP stimulates protein kinase reactions Proteins are phosphorylated Proteins get phosphates attached to them which activates or deactivates Phosphodiesterase degrades cAMP PIP calcium Mechanism Hormone binds to membrane receptor Modified receptor binds with G protein G protein is activated Activated G protein activates phospholipase Phospholipase splits Ple into DAG and P3 DAG activates protein kinases P3 triggers release of calcium from ER Calcium acts as additional second messenger Factors Affecting Hormone Action Hormone level in bloodstream Higher amount more response receptors inon target cells Body can produce more receptors up regulation Reduce number of receptors down regulation Receptor affinity Change way receptor binds to hormone Hormone Interactions Permissiveness Permits to work better Ex Hormone will affect reproductive development but if higher levels of thyroid present will have greater effect Synergism More than one hormone produces some effect so when both present have greater effect Ex glucagon and epinephrine together Antagonism ln opposition have opposite effects Ex glucagon vs insulin Modes of Endocrine Gland Stimulation Humoral Ex blood sugar Neural Nervous impulses stimulate gland Hormonal Hormone causes cell to produce diff hormone Modified by nervous system lnhibifed by negative feedback Endocrine Glands Pituitary Thyroid Parafhyroids Adrenals Pancreas Gonads Pineal Thymus Pituitary Gland Hypophysis Posterior pituitary Composed of nervous tissue Does not produce a hormone STORES them from hypothalamus and releases Anterior pituitary Tissue fused with other part Glandular tissue Produces lots of hormones Intundibulum Adenohypophysis anterior Neurohypophysis posterior 2 Neurohypophyseal Hormones Oxytocin Antidiuretic hormone ADH Oxytocin Stimulates smooth muscle contraction during labor Childbirth Milk ejection not production Sexual arousal and climax Sexual satisfaction Promote nurturing behavior cuddle hormone ADH Regulates water balance Prevents urine formation Cause kidneys to resorb wafer putting it back in circulation Alcohol suppresses ADH Adenohypophyseal anterior Hormones Growth hormone GH Thyroid stimulating hormone TSH Adenocorticotropic hormone ACTH Gonadotropins FSH and LH Prolactin PRL Pro opiomelanocortin POMC Pro hormone causes opiate substance Affects melanocytes Tropic Hormones A Hormone whose target cells are other endocrine cells Causes production of another hormone GH Anabolic hormone Builds tissue Muscle and bone Stimulates cell growth and division protein synthesis fat metabolism and glucose conservation More dctin or myosin Store glucose GH Cascade Hypothalamus secretes GHRH growth hormone releasing hormone Somatotropic cells stimulated by GHRH of anterior pituitary begin GH synthesis GH has both direct and indirect effects on tissues Circulating GH triggers production of GHIH growth hormone inhibiting hormone Aka somotostotin Production of GH stops Direct Actions of GH Increases blood levels of fatty acids Take Fats from fat stores make it available for energy Decreases glucose uptake and metabolism Keeps glucose in circulation for energy Encourages breakdown and release of glucose from glycogen in liver Called didbetogenic effect Indirect Actions of GH Operate through lGFs insulin like growth factors lGFs are produced by liver lDFs don t don t do much unless interacting with SH SH also increases productions of lGFs Stimulate uptake of amino acids from blood into cellular proteins Stimulate uptake of sulfur into background matrix of cartilage TSH Stimulates development of and secretion from thyroid gland TSH Cascade Hypothalamus secretes TRH thyrotropin releasing hormone TRH causes thyrotrope cells of anterior pituitary to produce TSH TSH thyrotropnin Increased levels of TSH inhibit both pituitary gland and hypothalamus Also stimulate production of GHIH GHIH also blocks TSH and GH ACTH adrenocorticotropic hormone ACTH is amino acid based Stimulates adrenal cortex to release corticosteroid hormones steroid based Especially glucocorticoids Type of hormone secreted by adrenal cortex Hormones from adrenal cortex All help body relieve stressors ACTH Cascade Hypothalamus secretes CRH corticotropic releasing hormone CRH stimulates corticotrope cells to release ACTH Increased levels of glucocorticoids stop CRH ACTH secretion stops Stops production of glucocorticoids Fever hypoglycemia and stressors promote CRH release Gonadotropins Regulate development and functions of gonads testis and ovaries Includes both FSH and LH FSH follicle stimulating hormone stimulates gamete production LH Ieutenizing hormone promotes production of gonadal hormones Testosterone estrogen Male FSH stimulates sperm production LH stimulates interstitial cells of testes to produce testosterone Female FSH stimulates ova eggs production Prior to birth and maintained in follicles 3 5 finish development every month FSH and LH cause maturation of follicle LH triggers ovulation and promotes synthesis of ovarian hormones Estrogen and progesterone Gonadotropin Cascade At puberty hypothalamus secretes GnRH GnRH stimulates gonadotrope cells of anterior pituitary to secrete gonadotropins Gonadotropins cause gonads to mature and begin producing hormones Increased levels of gonad hormones suppress FSH and LH Prolactin PRL Stimulates millltproduction by breasts May enhance testosterone production in males But males don t produce much Prolactin Cascade when Cycling High estrogen from developing ova shut off PIH Estrogen stimulates Iactotrope cells on anterior pituitary to secrete prolactin by suppressing PIH production Prolactin production brief due to ovarian hormone cycling Decreased estrogen stimulates production of PIH from hypothalamus Proldclin produclion slops Proldclin Cdscode when Pregndnl High eslrogen effecls some PRL Triggered nedr end of pregnancy when es rrogen levels high Suckling mdin rdins PRL produc rion As long 05 she is breder feeding conlinue To produce proldc rin dellt of suclltling dnd re rurn of normdl hormondl cycles brings dbou r PIH produclion Hormone Producing Sfrucfures Thyroid Gldnd 2 lobes connecfed by isfhmus dcross fronf Around frdched Ldrgesf pure endocrine gldnd Thyroid Hisfologicol Composifion Gldnd composed of follicles made up of epifhelial cells Produce fhyroglobulin Sfored ds colloid Thyroid hormone derived from colloid Also confdin pdrdfolliculdr cells Produce colcifonin Thyroid Hormone Acfuolly 2 sepdrdfe hormones T3 fhyroglobulin 0nd 3 iodine T4 fhyroglobulin 0nd 4 iodine Funcfions of fhyroid hormone lncredses dedl mefdbolic rdfe dnd hedf producfion Calorigenic effecf producfion of hedf fhrough bredkdown of glucose Mdinfdins blood pressure lncredses number of ddrenergic recepfors on blood vessels Consfricf blood vessels fo inc BP Reguldfes fissue growfh dnd developmenf Synfhesis Anferior pifuifdry secrefes TSH which frdvels fo fhyroid gldnd vid blood vessels TSH friggers producfion of fhyroglobulin which occumuldfes in follicles ds colloid TSH friggers dcfive frdnsporf of iodine info follicles Thyroglobulin is iodized To form T1 dnd T2 T1 dnd T2 link To form T3 dnd T4 T3 dnd T4 ore pockdged info lysosomes Lysosomdl enzymes free T3 dnd T4 dnd reledse fhem info bloodsfredm Diurndl Cycle Thyroid unique in fhdf if con sfore hormone TSH peaks before sleep and remains high at night Produced lols TH slored in extracellular colloid Transporl T3 and T4 musl bind lo lransporl proleins Major lransporl prolein is TBG lhyroxine binding globulin Delivered To largel cells and bind lo inlracellular receplors Transcriplion resulls jusl like s reroid Feedback Increasing levels of T4 inhibil TSH produclion Falling levels slimulale il Increase in body energy needs slimulale release of TRH Calcilonin Produced by parafollicular cells Called C cells Lowers blood calcium levels Take OUT of circulalion and pul in s rorage Mosl imporlanl in periods of rapid skelelon growlh and reformalion Childhood Ac on Inhibils osleoclasl aclivi ry Nol breaking il down any more so less in blood Slimulales calcium uplake and deposilion Feedback High calcium levels are humoral slimuli for C cell aclivily Low calcium levels inhibil C cell aclivily Slop producing calcilonin Paralhyroid Gland Embedded in in poslerior porlion of Thyroid gland Typically 4 Hislological Composilion Two Iypes glandular cells Oxyphil cells Unknown funclion Chief cells Secrele PTH Paralhyroid Hormone PTH Mosl imporlan r hormone in conlrolling calcium balance of blood Humoral lrigger low calcium High calcium levels shul off PTH Ac on Slimulales osleoclasls lo release calcium and phosphales lo blood Enhances reabsorplion of calcium by kidneys back inlo blood Increases absorplion of calcium by inleslines Get calcium from food Promotes kidneys to convert vitamin D to its active form calcitriol D3 Adrenal Glands Paired glands located atop each kidney Each comprised of cortex and medulla Secretes steroid hormones To fight off stress Adrenal Cortex Hormones Corticosteroids Mineralocorticoids Glucocorticoids Gonadocorticoids Histological Composition Zona glomerulosa Mineralocorticoids Zona fasiculata Glucocorticoids Zona reticularis Gonadocorticoids Mineralocorticoids Major hormone is aldosterone 95 Function to regulate electrolyte concentrations of extracellular fluids Sodium and potassium Action of aldosterone Stimulates sodium reabsorption back into bloodstream ln distal parts of kidney tubules Also from sweat saliva and gastric juice Other ions and water linked to sodium Therefore controls blood pressure and blood volume indirectly Feedback HUMORAL Aldosterone secretion stimulated by High potassium levels Low sodium levels Low blood volume Low blood pressure Mechanisms of Secretion Reninangiotensin mechanism Liver produces inactive angiotensinogen Kidneys when stimulated produce renin Renin converts angiotensinogen to angiotensin angiotensin Stimulates adrenal cortex to produce aldosterone Plasma concentration mechanism High potassium or low sodium have direct effect on zona glomeruloso We gel oldoslerone ACTH mechanism ACTH slimuldles oldoslerone produclion Nol much oldoslerone produced This woy Alrial nalriurelic peptide ANP Hormone produced by hedr r when BP gels high ANP inhibils renin which inhibils dldoslerone Glucocorlicoids Mdjor hormone is cor risol Funclion lo reguldle energy meldbolism of mosl body cells dnd resisl slressors Cold wedlher emoliondl slresses Ac on Mdinldin blood sugdr levels Gluconeogenesis produclion of new corbohydrdles from non corbohydrdles sources Mdinldin blood volume by prevenling upldke of woler by cells Prevenls woler from ledving bloodslredm in ro cells lnhibils woler upldke Feedbdck CRH promoles ACTH which promo res ddrendl gldnd To produce corlisol Corlisol inhibils bolh CRH dnd ACTH Effecls of Slress lncredse corlisol Increase gluconeogenesis Liberdle folly dcids for energy Toke OUT of s rordge Bredk down proleins inlo omino dcids Assis r in vasoconslriclion Gonddocor ricoids Mdjor hormones DHEA dre wedk dndrogens These converled lo lesloslerone dnd eslrogen Conlribule lo onsel of puberly Prior There is very lillle Provide sex drive lo women Feedbdck ACTH slimuldles produclion of lnhibilion nol noled Once we slorl producing conlinue lhrough life Adrendl Medulld Hormones Epinephrine Norephinephrine Hislologicol Composilion Chromaffin cells are modified ganglionic sympalhelic neurons I rs lhese lhal secrele Epinephrine and Norephinephrine Ac on Slress promo res release by slimulaling sympalhelic nervous syslem fighl or flighl Release of Epinephrine and Norephinephrine Blood sugar levels rise Need glucose Blood vessels conslricl Hearl beal increases Blood pressure rises Blood is diverled lo brain hearl skelelal muscles and preganglionic sympalhelic nerve endings in adrenal medulla Pancreas Localed in abdomen behind slomach Has bo rh exocrine ducl inlo small inlesline and endocrine hormones lo bloodslream componenls Hislological Composilion Acinar cells Mosl of pancreas Exocrine porlion Pancrealic islels lslels of Langerhans lmbedded in acinar cells Alpha cells produce glucagon Bela cells produce insulin Glucagon Funclions on liver lo release glucose inlo bloodslream Take OUT of s rorage Aclions of Glucagon Breaks down glycogen inlo glucose Syn rhesizes glucose from lactic acid and noncarbohydrale molecules Releases glucose inlo blood Feedback Low blood sugar levels and high amino acid levels exerl humoral conlrol And reverse Sympalhelic slimulalion epinephrine and norepinephrine of medulla promoles release Somaloslalin GHIH also inhibils release of glucagon lnsulin Lowers blood sugar levels Influences prolein and fal melabolism Aclions of Insulin Enhances membrane lransporl of glucose inlo cells Glucose laken up by cells lnhibits breakdown of glycogen into glucose Ledve it in stordge lnhibits conversion of dmino dcids or fdts to glucose lnhibit gluconeogenesis Promotes oxiddtion of glucose Promotes production of glycogen by liver Feedbdck High blood sugdr levels stimuldte production Also high levels of tdtty dcids dnd dmino dcids Parasympathetic nervous dctivity reledse of dcetylcholine stumldtes reledse Hormondl influences dlso exist Gondds Testes Ovories Sex Hormones predomindtes Mole Testosterone Femdle Estrogen Progesterone Actions Testosterone Mdturdtion dnd mdintendnce of mole reproductive orgdns dt puberty Seconddry sex chdrdcteristics muscle mdss body hdir oil deeper voice Sex drive Sperm production Estrogen Mdturdtion of femdle reproductive orgdns Seconddry sex chdrdcteristics hips bredst smoother skin higher voice curves Progesterone Functions with estrogen to Promote bredst development Couse cyclic chdnges in uterine lining Coordindtes menstruol cycle Feedbdck Reguldted by gonddotropin As levels get high shut themselves off Pinedl Gldnd Extends from root of third ventricle in diencephdlon Histologicol Composition Pinealocytes Hormone producing cells Responsible for melatonin Melatonin Promotes drowsiness Inhibited by sunlight Inhibits sexual maturation Therefore helps time puberty Thymus Deep fo sternum in thorax Size diminishes with age Very active when embryo and child 3 classes of Hormones Thymoproteins Thymic factor Thymosins Other Hormone Producers Hea ANP related to aldosterone when high blood pressure Shuts off aldosterone which increases urinary output Gastrointestinal tract Affect digestive activity Ex hormone produced by small intestine effects stomach Placenta Estrogen Progesterone hCG human chorionic gonadotropin Detected by pregnancy test Kidneys Erythropoietin hormone that stimulates production of RBC in bone marrow Skin Cholecalciferol inactive form of vitamin D3 Converted to active form by influence of sunlight D3 is important for absorption of calcium into digestive tract Adipose tissue Leptin reduces appetite and increases energy expenditure Endocrine Gland Development Arise from all three embryonic germ layers Mesoderm steroid producing glands Others amino acid derived Aging changes rate of hormone production Ex thymus reproductive Can be affected by environmental cues Ex cold