22.2.Anatomy.txt

22.1 Endocrine Glands Defined Innkirtlakerfið What is the difference between the endocrine and exocrine glands? Endocrine glands secrete their products (hormones) into the interstitial fluid surrounding the secreting cells. The blood transports hormones throughout the body after they move into th...

22.1 Endocrine Glands Defined Innkirtlakerfið What is the difference between the endocrine and exocrine glands? Endocrine glands secrete their products (hormones) into the interstitial fluid surrounding the secreting cells. The blood transports hormones throughout the body after they move into the blood capillaries from the interstitial fluid. The [endocrine glands] include the pituitary, thyroid, parathyroid, adrenal, and pineal glands In addition, there are several other organs and tissues that do not function exclusively as endocrine glands but contain cells that secrete hormones. These include the hypothalamus, thymus, pancreas, ovaries, testes, kidneys,stomach, liver, small intestine, skin, heart, adipose tissue, and placenta. Taken together, all endocrine glands and hormone-secreting cells constitute the endocrine system. Exocrine glands, on the other hand, secrete their products (sweat, oil, mucus, and digestive juices) into ducts that carry the secretions into body cavities, into the lumen of an organ, or to the outer surface of the body. Exocrine glands include sudoriferous (sweat) glands, sebaceous (oil) glands, mucous glands, and digestive glands. Function of Hormones Help regulate: Chemical composition and volume of internal environment (interstitial fluid) Metabolism and energy balance Contraction of smooth and cardiac muscle fibers Glandular secretions Some immune system activities 2.Control growth and development. 3.Regulate operation of reproductive systems. 4.Help establish circadian rhythms. Clinical connection Synthetic hormones that block the receptors for certain naturally occurring hormones are available as drugs. For example, RU486 (mifepristone), which is used to induce abortion, binds to the receptors for progesterone (a female sex hormone) and prevents progesterone from exerting its normal effects. When RU486 is given to a pregnant woman, the uterine conditions needed for nurturing an embryo are not maintained, embryonic development stops, and the embryo is sloughed off along with the uterine lining. RU486 is often used in conjunction with one or two other drugs, methotrexate and misoprostol. This example illustrates an important endocrine principle: If a hormone is prevented from interacting with its receptors, the hormone cannot perform its normal functions. Checkpoint Which of the following is exclusively endocrine gland: thymus, pancreas, placenta, pituitary, kidney, sodoriferous glands, mucous glands, testes, ovaries? 22.2Hormones Objective Hormoni imaju jako veliki uticaj cak i u malim dozama. Iako hormon putuje telom preko krvi on samo deluje na odredjene celije. Samo celije koje imaju receptore za odredjeni hormon ce se aktiviratu u prisustvu tog hormona. Receptori koji i ostali proteini u celiji se konstantno formiraju i razgradjuju. Obicno ciljana celija ima od 2000 do 100 hiljada receptora za odredjeni hormon. Ako je kolicina hormona veca nego sto je potrebno onda se odredjeni receptori ugase, tako hormon manje utice na celiju. Ako se u suprotnom kolicina hormona smanji na manje od normalnog, onda se broj receptora na celiji uveca. Check Point Explain the relationship between target cell receptors and hormones 22.3Hypothalamus and Pituitary Gland Objective Objasni zasto je hipotalamus klasifikovan u endokrine zlezde Objasni polozaj, histologiju, hormone i funkciju adenohipofize (anterior pituitery gland,kirtildingull) Obajsni polozaj, hostologiju, hormone i funkciju neurohipofiza (posterior pituitery gland, taugadingull) Hypothalamus Mnogo godina je vladalo misljenje da je hipofiza glavna endokrina zlezda, zato sto luci veliki broj hormona koji kontrolisu druge endokrine zlezde, medjutim danas znamo da hipofiza ima svog sefa a to je hipotalamus. Ovo je mali deo mozga inferioran u odnosu na talamus. Ovaj deo mozga je osnovni link izmedju nervnog i endokrinog sistema. On prima signale od drugih delova tela kao sto je limbicni sistem, cerebralni korteks, talamus, retikularni aktivacioni sistem (RAS). Takodje prima signale od unutrasnjih organa i retine. Bolne, stresne i emotivne situacije izazivaju promene na hipotalamusu. Tako da hipotalamus utice na autonomni nervni sistem kao sto je temperatura tela, zedj, glad, seksualno ponasanje, kao i na odbranbene reakcije kao na primer strah i bes. Tako da hipotalamus nije samo vazan regulatorni centar mozga nego takodje je jako vazan kao zlezda. Hormoni koje luci hipotalamus i hipofiza kontrolisu doslovce sve aspekte rasta i razvoja, metabolizma, i homeostaze. Pituitary Ovo je mala zlezda velicine oko 1-1,5cm i nalazi se u hipofizijalnoj fosi sfenoidne kosti, i vezana je za hipotalamus. Hipofiza ima dva posebna dela, kako funkcionalno tako i anatomski, prednji rezanj (adenohipofiza) (anterior pituitary gland), i straznji rezanj (neurohipofiza) Anterior Pituitary Prednji rezanj, predstavlja ukupno 75% cele zlezde, i sastavljeno je od epitelnog tkiva. Kod odraslih se sastoji iz dva dela, pars distalis je veci deo i pars tuberalis. Anterior Pituitary ili adenohipofiza (adeno-zlezda), luci hormone koji kontrolisu veliki broj telesnih aktivnosti, od rasta do reprodukcije. Izlucivanje hormona adenohipofize se kotrolise putem hipotalamusa, koji salje hormone koji podsticu ili zaustavljaju lucenje. Ovi hormoni dolaze do adenohipofize putem “portalni sistem”, hypothalamic-hypophyseal portal system, krvni tok iz hipotalamusa do hipofize, krv tece iz kapilara hipotalamusa do adenohipofize /framheiladingull/ preko portalne vene do kapilara adenohipofize. Ovako se formira veza izmedju nervnog sistema i endokrinog sistema. Kada iz hormoni is hipotalamusa preko portalnog kanala stignu do hipofizne vena vec su oslabljeni i kao takvi idu putek krvi do svojih odredjenih destinacija. Hormoni koji se luce od adenohipofize Human Growth Hormon hGH, hormon rasta, drugacije se zove somatotropin (soma-telo, tropin-growth or movement)(topical application, ne tropical application, za nanosenje preko koze) hGH Human growth hormone nakon toga stimulise insuline like grwoth factors (IGFs), hormon koji stimulise rast tela i regulise posebne aspekte metabolisma Thyroid stimulating hormon TSH ili thyrotropin; koji kontroliše lučenje i aktivnost tiroidne žlezde. celije koje obavljaju ovu funkciju se zovu ne celije tirotrofa, thyrotrophs Follicle stimulating hormone FSH, hormon stimulacije folikula, jedan od gonadotropnih hormona, koji igra kljucnu logu u reprodukciji. Oni luce estrogen i progesteron, koji Kod žena stimuliše rast i zrenje oocita (oocytes) u jajniku tokom menstrualnog ciklusa, kod muskaraca podstice proizvodju spermatozoida. Prolactin PRL , utice na proizvodnju mleka i luce ga celije zvane laktotrofi. Adrenocorticotropic horomon ACTH, ili kortikotropin, koji stimulise adrenalni korteks da luci glucocorticoids. Neki kortikotrofi isto luce hormon za stimulaciju melanocita, melanocyte-stimulating hormon (MSH) 5 razlicitih vrsta celija adenohipofize Somatotrophs Thyrotrophs Gonadotrophs Lactotrophs Corticotrophs Koji se mogu grupisati po reakciji na hemijsko bojenje Basophils Acidophils Chromophobes Tropic hormons Tropins Cetiri hormona adenohipofize, se zovu tropni hormoni (tropic hormones, tropins), TSH; ACTH; FSH i LH. Ima jos dva gonadotropina- FSH; LH koji regulisu jajnike i testise.