Chapter 16

Chapter 16Endocrine SystemIntroductionMaintains homeostasis through hormone regulation throughout the bodyComparable to the nervous system and the controls previously learnedRegulation chemical messages to the cells (glands or neurons)Target cells and tissues receive hormones from various glands throughout the bodyHow are hormones taken to these target cells?Hormones Effect the body slowly, but lasts long timeSecreted by ductless (endocrine)glandsExocrine glands excrete products into ducts (oil, sweat, hydrochloric acid, etc)Some glands contain neurosecretory tissue modified neurons that secrete chemicals into the blood rather that across a synapseHormone classificationTropic target other endocrine glands to stimulate growth and secretionSex reproductive tissuesAnabolic stimulate anabolism (cells making hormones from chemicals)

ORSteroidNonsteroid

CorticosteroidsIndications (usages)Reduce swellingReduce inflammationProsAsthmaPoison IvyConsThin skinIncreased HDLPrednisone True or False QuizAnabolic steroidsROIDSIndicationsSlow physiological developmentLow testosterone levelsProsMuscle mass production at a rapid rateIncreased self-esteemConsIncreased emotional responseIncreased cancers/growthsIncreased heart/liver diseaseIT IS ILLEGAL !!!!!!

Steroid hormonesMade from cholesterol that can pass through plasma membranes to target cells

Examples: cortisol, aldosterone, estrogen, progesterone, testosteroneSteroid hormone actionLipid-soluble and found in target cell cytosolAfter diffusion into target cell, it binds to receptor molecule to form hormone receptor complex(hypothesis)Activates a gene in the nucleus to transcribe mRNA to ribosomes and makes protein molecules that produce the effect of the hormoneThe amount of steroid hormone determines intensity of effectSlow processNon-steroidal hormonesMade from amino acids (proteins and glycoproteins)

Insulin, parathyroid hormone, oxytocin, antidiuretic hormone, epinephrine, nor-epinephrineNon-steroidal actionFixed membrane receptor hypothesisNS hormone is first messenger and delivers chemical message to the target cells plasma membraneMessage passed by G proteins to second messenger triggers and appropriate cellular changes occurHormone functionSignal target cells receptorsVarious receptors produce different regulatory functions/chemical reactionsHormone glands produce more than is necessary and left-overs are excretedCombined hormone actions allow for special functionCombined hormone actionsSynergism many working together on target cells for better performance

Permissiveness small amounts of one hormone allows for another to have full effect on target cell

Antagonism opposing effects to fine tune activity of target cellHormone regulationNegative feedback loop (endocrine reflex)

Physiological changes

Regulation by another gland

Nervous system inputProstaglandins Lipid moleculesTissue hormonesDiffuses to neighboring cells in the tissue Examples:PGA intraarterial infusion creates hypotensionPGE- vascular regulation (RBC, thrombocyte), GI system (hydrochloric acid)PGF uterine contractions, GI motility

Secretion of protaglandins: kidney, lung, iris, brain, thymusPituitary

Master gland

Master gland/hypophysis: in size, weight 0.5 gVentral surface of the brainStem connects the pituitary to the hypothalmusContains two glands Anterior adenohypophysisPosterior - neurohypophysisAnterior Two parts pars anterior/pars intermediaIrregular clumps of secretory cells supported by fibers and interweaved with great vascularityThree types of cellsChromophobes do not stainAcidophils stain with acidsBasophils basic stainsFive functionsSomatotrophs GHCorticotrophs ACTHThyrotrophs TSHLactotrophs prolactin PRLGonadotrophs LH/FSHGH growth hormoneAlso STH (sonatotropin)Promotes growth of: bone, muscle, other proteins to cellsStimulates USE of lipids speeds up catabolism of lipidsShifts cells from glucose catabolism and toward lipid catabolism as an energy source THIS LEADS TO INCREASED BLOOD GLUCOSE LEVELSProlactinReleased during pregnancy, after birth, during disease

Stimulates milk production from the mammary glandTSHThyrotropinGrowth and development of the thyroid

Causes secretion of thyroxinACTHAdrenocorticotropic hormoneNormal growth and development of cortex of the adrenal gland and secrete adrenalineFSHGraafian follicles to grow to maturity

Estrogen secretion female

Spermatogenesis - male

LHFemale stimulates the corpus luteum which then secretes progesterone /estrogenAlso assists FSH for egg maturation

Male enables testes to develop and secrete testosteroneFSH and LH called gonadotropins because they stimulate the growth and maintainance of the gonads.Adenohypophysis Hypothalamus releases hormones into the blood which are then carried to the hypophyseal portal systemThe hypothalamus adjusts secretions of the adenohypophysis which then adjusts the secretions of the target cellsDuring stress, the hypothalamus translates nerve impulses into hormone secretions by the endocrine glandsNeurophyophysisServes as storage and release site for ADH and oxytocin which are made in the hypothalamusRelease into the blood is stimulated by nerve impulseADH regulates fluid content in the blood by regulation of filtration in the kidneyDehydration will trigger ADH releaseOT lactation, uterine contraction for birthPineal glandPart of the nervous and endocrine system Located in the brainLooks like a pine coneBiological clockSecretion of melatonin (happy hormone) puberty, responds to light (inhibits production) can cause seasonal affective disorder (winter depression)

ThyroidTwo large lobes1 oz.Anterior/lateral surface of trachea below larynxThyroid hormone synthesized in follicles

Although the thyroid gland releases the hormones which govern growth and metabolism, the brain (the pituitary and the hypothalamus) regulates the thyroid's activity.

Thyroid hormonesStores hormones only endocrine gland that does thisRegulates metabolism, cell growth and tissue differentiation Three hormones produced: T-3, T-4, calcitoninCalcitonin processing of Ca by bones,bloodT-3 three iodine atoms More potent than T-4The main thyroid hormoneT-4 four iodine atoms 20 times more released than T-3When released to the target cells, it becomes T-3

Thyroid abnormalitieshyperthyroisdismhypothyroidismGraves diseaseHashimotos DiseaseWt. lossExopthalmosNervousnessIncreased heart rateIncreased respiratory rateIncreased metabolismCretinismSlow metabolismRetarded growthRetarded sexual developmentOcc. Mental retardationOcc. Deformed dwarfism (unproportionate)SluggishLoss of hairJaundiceMyxedema Graves

Cretinism

Parathyroid Four embedded to the posterior lateral surface of the thyroidsPTH parathyroid hormone antagonist to calcitoninPTH acts on bone and kidney cells to release Ca into the blood

Adrenal glandsAbove the kidney

Outer adrenal cortex

Inner adrenal medullaCortex Three layers each producing a specific hormoneOuter mineralocorticoids electrolytesAldosterone regulates Na, K, and blood pH and regulates BP (pg.507) Middle glucocorticoids reg. BP, immune responseCortisol TMT of inflammation, regulates serum glucoseInner glucocorticoids and gonadocorticoids releases sex hormones from the adrenal cortex (androgen)Adrenal medullaNeurons secrete products into blood rather than through the synapseSympathetic nervous response as in fight/flight responseTwo hormones secreted: epinephrine (fight or flight) and nor-epinephrine (increases cardiac output)

Pancreatic IsletsPancreas 5-6 longpancreatic islets cells that produce various hormones

Alpha glucagonBeta insulinDelta somatostatinPolypeptide cells polypeptide

Pancreatic hormonesGlucagon increase serum glucose converts glycogen to glucose in liver also changes lipids/amino acids into glucoseInsulin transports glucose from these sources from blood to cellular levelSomatostatin inhibits secretion of glucagon, insulin, polypeptides, and growth hormone from the pituitaryPolypeptide ??? digestion and distribution of nutrients???GonadsSex organs ovary/testes

Ovaries Inside the pelvisProduces estrogenProduces progesterone (pregnancy-promoting) maintains placental lining during pregnancy

Testes contained within the scrotumOutside the pelvisProduces spermProduces testosterone

PlacentaInterface between mother and babyProduces BhCG referred to as chorionic. ( Beta human chorionic gonadotropin)High during first trimester then level lowers

Thymus Located by the heart (mediastinum)Lg. until puberty then will atrophyPrimarily lymphatic tissue, it secretes thymosin/thymopoietinDevelopment of immune process (T-cells)Gastric/intestinal mucosaGastrinSecretin reduces stomach acid secretion and release an alkaline solution also triggers pancreas to secrete digestive enzymes and the liver to produce bileGhrelin causes hypothalamus to increase appetite, slow metabolismCholecystokinin pancreozymin CCKHeart Atrial natriuretic hormone

Produced in atrium and causes Na to be excreted from the urine to reduce blood pressureLibrary research:DiabetesDiabetesType I

Type II

Gestational

Pre-diabetic syndromeDiseasesGraves hypersecretion thyroidCretinism/myxedema hyposectretion thyroidAcromegaly hypersecretion pituitaryCushings hypersecretion pituitaryCushings disease hypersecretion glucocorticoidsGigantismAddisons hyposecretion adrenal cortex