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Zašto ljudi imaju probavni sistem napred, a bubrege pozadi?

Zašto ljudi imaju probavni sistem napred, a bubrege pozadi?


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Izlaz iz digestivnog sistema je prisutan na zadnjoj strani tela, ali njegov probavni sistem na prednjoj strani.

Izlaz urinarnog sistema je prisutan ispred tela, ali njegov sistem je prisutan pozadi.

Zašto ljudi imaju probavni sistem napred, a bubrege pozadi?


Ne tvrdim da imam potpuni odgovor zašto su ovi organi locirani na način na koji jesu, ali mislim da ovi faktori utiču na anatomiju:

1- Veza mokraćnog sistema sa reproduktivnim sistemom kod muških sisara: izlaz muškog reproduktivnog sistema mora biti lociran što je više moguće napred kod sisara sa 4 noge kako bi se olakšala seksualna funkcija, prisiljavajući urinarni sistem da ga prati

2- Bubrezi su vrlo krhki i moraju biti zaštićeni debelim mišićima leđa i dijelom ispod grudnog koša. Bili bi previše ranjivi na frontu

3- Mokraćni sistem je generalno sterilan od bakterija, kao i reproduktivni sistem kod muškaraca, a delimično i kod žena. Probavni sistem nije sterilan u oba slučaja. Izlaz iz digestivnog sistema ne može biti ispred genitalija kod mužjaka jer će to povećati rizik od urinarnih infekcija u celini, kao i od genitalnih infekcija nakon parenja. Iz istog razloga ne može biti između urinarnog i reproduktivnog otvora, tako da mora biti lociran iza oba kako bi najmanje ometao njihove funkcije


Pogled u vaš probavni sistem

Priyanka Chugh, MD, je certificirani gastroenterolog sa iskustvom u internoj medicini. Ona vježba u Trinity Health of New England​ u Waterburyju, Connecticut.

Probavni sistem se sastoji od nekoliko organa koji funkcionišu zajedno kako bi razgradili hranu koju jedete u molekule koje vaše tijelo može iskoristiti za energiju i hranjive tvari. Probavni trakt uključuje usta, jednjak, želudac, crijeva i anus. Takozvani "dodatni" organi uključuju jetru, gušteraču i žučnu kesu, hrana se ne kreće kroz ove organe, ali oni luče hormone i hemikalije koje su neophodne za varenje. Evo šta treba da znate o organima i funkcijama vašeg probavnog sistema.


Struktura jetre

Jetra je crvenkasto smeđe, klinaste strukture. Kod odraslih osoba, jetra je obično teška oko 1,5 kg (oko 3,3 lb). To je i najteži unutrašnji organ i najveća žlijezda u ljudskom tijelu. Jetra je podijeljena na četiri režnja nejednake veličine i oblika. Svaki režanj se sastoji od lobula, koji su funkcionalne jedinice jetre. Svaka lobula se sastoji od miliona ćelija jetre, zvanih hepatične ćelije (ili hepatociti). One su osnovne metaboličke ćelije koje obavljaju različite funkcije jetre.

Kao što je prikazano na slici 15.6.3, jetra je povezana sa dva velika krvna suda: hepatičnom arterijom i portalnom venom. Hepatična arterija prenosi krv bogatu kiseonikom iz aorte, dok portalna vena nosi krv koja je bogata probavljenim nutrijentima iz GI trakta i otpadom koji iz krvi filtrira slezena. Krvni sudovi se dijele na manje arterije i kapilare, koje vode u lobule jetre. Hranjive tvari iz GI trakta koriste se za izgradnju mnogih vitalnih biohemijskih spojeva, a otpad iz slezene se razgrađuje i izlučuje.

Slika 15.6.3 Portalna vena opskrbljuje jetru otpadom koji se filtrira iz krvi u slezeni, kao i hranjivim tvarima iz gastrointestinalnog trakta. Krv bogata kiseonikom ulazi u jetru preko jetrene arterije.


Hronični donji abdominalni simptomi

Kao i kod simptoma gornjeg abdomena, bol u donjem dijelu abdomena ne znači nužno da je problem u crijevima, jer bol može zračiti. Međutim, postoji nekoliko probavnih poremećaja koji mogu doprinijeti crijevnim simptomima, uključujući bol u donjem dijelu trbuha, grčeve i probleme s pražnjenjem crijeva.

Evo nekih od najčešćih:

    : Ljudi koji imaju celijakiju ne mogu jesti gluten jer oštećuje tanko crijevo. Ovo je stanje koje bi vam trebao dijagnosticirati zdravstveni radnik, a često se pogrešno smatra drugim gastrointestinalnim poremećajima prije nego što bude prepoznato. : Divertikulitis je upala divertikula, koji su izbočine u zidovima crijeva. Simptomi uključuju oštre bolove u donjem lijevom dijelu trbuha, obično praćene povišenom temperaturom. Ako se ne liječi, divertikulitis može uzrokovati komplikacije opasne po život. : Ovo je krovni izraz za dva odvojena stanja: Crohnovu bolest i ulcerozni kolitis. Oba su hronična stanja koja zahtijevaju doživotno praćenje i liječenje. : Ljudi koji se bave ovim vrlo čestim probavnim poremećajem imaju ponavljajuće bolove u trbuhu, ili dijareju, zatvor ili oboje.

Uloga tankog crijeva u apsorpciji tekućine

Na našu sreću, tanko crijevo je više nego doraslo zadatku. To&rsquos je prilično opsežan organ, koji se može pohvaliti dužinom od oko 20 stopa (6 metara). Takođe ima ogromnu unutrašnju površinu od otprilike 250 kvadratnih metara &ndash veličine teniskog terena! (Izvor) Ova velika površina pomaže da se voda i druge tekućine apsorbiraju brzo i efikasno.

Od skoro 10 litara vode koja svaki dan uđe u naš želudac, 80-90% se apsorbira u tankom crijevu. Preostalih 10% (što iznosi 1 litar vode) se prenosi u debelo crijevo, koje apsorbira što je moguće više vode iz otpadnih tvari koje su spremne za izlučivanje iz tijela kao feces.


16 komentara

Imam kamen u žuči nalik pesku.
Imam kamen u žuči nalik pesku. Hirurg mi je rekao da je najgora stvar koju mogu učiniti je ispiranje jetre/žučne kese jer bi to moglo uzrokovati da mali kamenčići uđu u kanal gušterače i izazovu pankreatitis. Napravio sam brojne ispiranja tokom godina, ali nakon što sam ovo čuo, uplašio sam se. Ima li istine u ovome, i zato što imam kamenje nalik pijesku da li je bolje ukloniti žučnu kesu? Mark

Pitajte svog kirurga da li on&rsquos kaže da ispiranje jetre/žučne kese zaista djeluje, da zaista ispire kamen iz žučne kese i da je korisno za većinu ljudi, samo ne za vas. To bi bilo izvanredno za hirurga da prizna efikasnost ispiranja jetre/žučne kese. Međutim, ako vam kaže da oni ne&rsquot ne djeluju i da mogu&rsquot isprati bilo šta iz vaše žučne kese, onda se postavlja pitanje: kako onda mogu biti opasni za vaš pankreas i zašto bi on to rekao? Morate razjasniti da li vaš doktor zaista daje informisanu izjavu ili samo pokušava da vas uplaši. Kada to saznate, bićete u boljem položaju da sami donesete informisanu odluku.

Hirurg je rekao da niko ne može
Hirurg je rekao da se nikome ne može pomoći. Molim te... zaboravimo na njega. ZNAM DA JE ISPIRANJE DOBRO. ONO ŠTO PITAM I TREBA DA ZNAM JE….DA LI IMATE TEŠKE DOKAZE I TEŠKO OBJAŠNJENJE O ….DA LI I KAKO MOJI ŽUČNI KAMECI MOGLE DA ZAHVATU KAMENE U PANKREASU. OČAJAN MI JE ISKREN EDUCANI ODGOVOR PRIRODNOG LIJEČNIKA. Unaprijed hvala na odgovoru.

Nije me briga šta
Nije me briga šta bilo koji hirurg kaže. Želim znati kako da izbjegnem zaglavljivanje kamenca u kanalu pankreasa. Mogu li nešto prirodno da uradim?

Iz očiglednih zakonskih razloga, ne možemo dijagnosticirati ili propisivati ​​određene bolesti. Samo dajte informacije. Iz tog razloga, naša stranica sadrži mnogo informacija o prirodnim metodama kako za omekšavanje kamenca tako i za njihovo izbacivanje iz tijela. Morate pročitati te informacije, a zatim donijeti vlastite odluke.

Ja sam predložio askorbinsku
Prijatelju sam u prošlosti predložio askorbinsku kiselinu za kamen u ovom slučaju.

Ubrzo nakon što je probao C, imao je vrlo bolnu epizodu kamenja iz bubrega.

U početku je bio uznemiren i okrivio C za kamenje. Međutim, brzo se predomislio i samo prolazak kamenja pripisao C.

Askorbinska kiselina je vrlo agresivna kiselina, toliko agresivna da će otupiti staklo. Nikada se ne smije koristiti kao vodica za ispiranje usta, međutim protiv kamenca može donijeti određeno olakšanje. Danju koristim askorbinsku kiselinu C, a noću prelazim na kalcijum askorbat C, jer pokušavam da podignem pH svog tijela noću. Nakon uzimanja askorbinske kiseline u prahu, koristim vodu za ispiranje usta sa sodom bikarbonom kako bih neutralizirala preostalu askorbinsku kiselinu u ustima. Voda za ispiranje usta od sode bikarbone također može neutralizirati kiselinu koju proizvodi stafilokok u ustima.

Mark,
Ovaj članak je pomogao

Mark,

Ovaj članak mi je izuzetno pomogao. Hvala vam što ste pružili dobro napisano, lako razumljivo i sveobuhvatno objašnjenje zdravlja pankreasa. Definitivno ću se pretplatiti na vaš bilten!

Imao sam hroničnu
Imam hronični pankreatitis od jula 2005. Prije nego što sam shvatio sve što mi je nedostajalo po rođenju, hirurg mi je uradio biduktornu sfinkterotomiju. Imam urođeni nedostatak žučne kese i cističnog kanala i ventralnog kanala u pankreasu. Dorzalni kanal je također nefunkcionalan, pa iako imam dijagnozu divizma pankreasa s kroničnim pankreatitisom, u osnovi funkcioniram samo kroz manji papilarni kanal u pankreasu radi drenaže. Imam ogromne bolove…konstantno i godinama sam na narkoticima zajedno sa mnogim enzimima pankreasa i drugim lijekovima za poboljšanje probavnog procesa. Imam teški gastritis zbog prekomjernog nakupljanja kiseline u mom sistemu zbog čega sam u osnovi bio sirov od usta do anusa. Prošao sam kroz mnoge doktore, mnogo simptoma, i tako sam umoran od toga da budem tako bolestan. Neki prijedlog? Teško mi je priuštiti redovno viđanje lokalnog naturopata zbog troškova, ali ako biste me mogli uputiti u smjeru enzima i ishrane, bilo bi vam jako zahvalno. Trenutno pokušavam da odviknem od svojih lijekova, postavim spinalni stimulator ili pumpu i pokušavam učiniti sve što mogu prirodno da zaustavim napredovanje ove bolesti. Već je viđeno da moj pankreas ima cijela gušterača zahvaćena lobularnim tkivom zbog činjenice da se sama probavlja zbog enzima koji se prethodno otpuštaju u moj pankreas. Još mnogo toga da se kaže, ali ne želim da vas preopterećujem. Hvala ti.

hej, poludio sam na test krvi IgG 4
hej, poludio sam na test krvi IgG 4 i bio je više od normalnog sa jednom zvjezdicom *. moj doktor me je zamolio da uradim skeniranje i uradio sam, ali je viđeno nthng opasno!! pa mi je rekao da imam upale u pankreasu!! kog doktora da posetim?? bilo kakva pomoć?? imam problema sa varenjem

Iz očiglednih pravnih razloga, mi
Iz očiglednih pravnih razloga, ne možemo postaviti dijagnozu ili propisati određena medicinska stanja i samo pružamo informacije. Uz to rečeno&hellip

Da, viši nivoi IgG 4 od normalnog su pokazatelj autoimunog pankreatitisa i između ostalog. Kombinujte to sa svojim problemima sa varenjem i možda ćete želeti da vaš lekar proveri začepljenje žučnih kanala. Možda biste željeli pogledati i ovaj izvještaj, koji sadrži informacije o tome kako isprati jetru, žučnu kesu i žučne kanale. https://www.jonbarron.org/detox/program-phase-three-liver-blood-cleansing. Imajte na umu da ćete prije detoksikacije jetre htjeti obaviti čišćenje crijeva i ispiranje bubrega u pripremi.

Imao sam šivanje 5 godina
Prije 5 godina radila sam vip zbog IPMT-a u glavi, 3 cm. Sada sam na enzimima, ali također patim od fibromijalgije sa simptomima IBS-a. Ono što bih želio znati da li je ovo onoliko dobro koliko ću dobiti? Imam stalne bolove i otoke posebno na kraju dana. Trudim se da jedem povrće i voće sa malo mesa, bezglutenskim proizvodima i sa malo natrijuma i šećera.

zdravo
zdravo
Ovo je vrlo interesantan članak i objasnio je funkcije pankreasa dovoljno jednostavno, ali informativno za laika poput mene. Nastavit ću više o tome kako da se nežno brinem o svom pankreasu, jetri i žučnoj kesi, 3 često zanemarena organa.

Bog blagoslovio i nastavi sa dobrim radom.

Zdravo, imam ovaj tipičan maksimum
Zdravo, imam tipično visok nivo triglicerida. Pokušao sam kontrolirati ishranu, ali još uvijek nije kontroliran. Neki doktori sugerirali su da je to možda zbog nepravilne funkcije pankreasa

Žao nam je što to čujemo

Žao nam je što čujemo da imate visoke nivoe triglicerida. Međutim, imajte na umu da Fondacija prima hiljade e-mailova i komentara mjesečno i da nemamo osoblje koje bi lično odgovaralo na pitanja. Mi smo neprofitni, besplatni — samo izvor zdravstvenih informacija na mreži. Pružamo hiljade stranica informacija o raznim temama koje možete koristiti kao resurs. Ako to već niste učinili, koristite funkciju TRAŽI ugrađenu u gornjem lijevom kutu svake stranice na web stranici. Postoji velika šansa da je Jon već riješio vaš problem. Na primjer, jeste li pročitali gornji članak do kraja?

zdravo Marko,
zdravo Marko,
Zaista sam uživao čitajući ovaj članak jer tražim informacije o pankreasu i otkrio sam da mi je zaista teško pronaći puno…
Dijagnostikovana mi je teška atrofična pankreasa sa masnom infiltracijom… Uradila sam neke krvne pretrage i čini se da su mi nivoi lipaze malo niski.
Dosadašnji doktori su zbunjeni mojim slučajem. Uradio sam endoskopiju, mislim da su tražili da vide da li imam pankreatitis što nemam.
Šta može biti uzrok “smanjenog” pankreasa?
Obično pijem 1 koktel ili čašu vina oko 5 dana u nedelji. Prestao sam pušiti prije otprilike 7 godina. Ne jedem prerađenu ni masnu hranu. Svaki dan kuvam sveže obroke, jedem puno voća i povrća.
Ja sam žena 47 godina btw.
U mojoj porodici postoji porodična istorija problema sa pankreasom. Moja majka je imala probleme, moja baka sa mamine strane takođe je imala i sada izgleda da počinjem da imam probleme a moj stariji brat ima masni pankreas.
Ima li tragova?
Brinem se da ću na kraju završiti sa “nefunkcionalnim” pankreasom…
Hvala ti
Luiza

Ne bi trebalo da pijete
Sa hroničnim pankreatitisom uopšte ne bi trebalo da pijete. To će uzrokovati bol i upalu pankreasa.

vrlo informativno,
Vrlo informativan, opsežan članak, hvala!


Izlučivanje kod životinja, ljudi i biljaka (sa dijagramom)

U stanicama živih organizama cijelo vrijeme se odvijaju kemijske reakcije kako bi se odvijali životni procesi.

Zbir ovih reakcija naziva se metabolizam. Metabolizam proizvodi korisne proizvode kao i toksične (otrovne) nusproizvode.

Ove otrovne tvari se moraju ukloniti jer su štetne ako se dopuste da se akumuliraju. Uklanjanje metaboličkih otpadnih produkata iz tijela organizma poznato je kao izlučivanje.

Glavni produkti izlučivanja su ugljični dioksid, višak vode i dušikovi spojevi kao što su amonijak, urea, mokraćna kiselina itd. Ugljični dioksid i voda nastaju u procesu disanja tkiva. Azotna jedinjenja nastaju razgradnjom proteina i aminokiselina. Voda i soli koje su veće od potreba tijela se također izlučuju.

Većinu vode dobivamo hranom i pićem, a dio metabolizmom, na primjer, vodom proizvedenom tokom ćelijskog disanja. Ostali proizvodi izlučivanja uključuju kemikalije iz lijekova, toksične tvari i cirkulirajuće hormone koji su već ispunili svoju svrhu. Naučit ćemo kako se metabolički otpad eliminira.

Izlučivanje kod životinja:

Mnogi jednoćelijski organizmi poput Amebe izbacuju svoj otpad difuzijom sa površine tijela. Protozoe nemaju organe za izlučivanje. Kako žive u vodenom staništu, njihov otpad se eliminira difuzijom kroz plazma membranu.

Jednostavni višećelijski organizmi poput Hidre izbacuju čvrstu otpadnu materiju kroz usta. Viši višećelijski organizmi imaju dobro definisane specijalizovane organe za izlučivanje. Ovi organi mogu biti jednostavne cevaste strukture kao kod pljosnatih crva i pijavica.

Organi za izlučivanje insekata (npr. skakavca, žohara i kućne muhe) su također cjevasti. Oni uklanjaju dušične otpadne tvari iz tjelesne tekućine i pomažu u održavanju ravnoteže vode u tijelu.

Kod kičmenjaka, glavni organi izlučivanja i održavanja ravnoteže vode su bubrezi.

Izlučivanje kod ljudi:

Iako su bubrezi glavni organi izlučivanja, u izlučivanju pomažu i koža, pluća i jetra.

Naša koža ima znojne žlezde kroz koje izlučujemo male količine vode, uree i soli.

Jetra izlučuje žuč, koja sadrži žučne pigmente. Oni nastaju razgradnjom starih eritrocita u jetri. Kako se hemoglobin razgrađuje, njegovo željezo se zadržava, dok se pigment (hem) izlučuje žučom. Jetra takođe izlučuje holesterol.

Pluća pomažu u oslobađanju ugljičnog dioksida, koji nastaje kao rezultat ćelijskog disanja, kroz izdisaj.

Ekskretorni sistem kod čoveka:

Naš ekskretorni sistem se sastoji od bubrega, krvnih sudova koji im se spajaju, uretera, mokraćne bešike i uretre. Pomažu u proizvodnji i izlučivanju urina.

Postoje dva bubrega u obliku graha koja leže u trbušnoj šupljini, po jedan sa obe strane kičmenog stuba. Bubrezi su crvenkasto smeđi. Svaki od njih je dugačak oko 10 cm i težak oko 150 g. Iako su manje težine, primaju mnogo krvi za filtraciju.

Zapremina krvi koja je skoro jednaka onoj u cijelom tijelu prolazi kroz bubrege svakih četiri ili pet minuta. Bubrezi proizvode urin kako bi filtrirali otpadne produkte, poput ureje i mokraćne kiseline, iz krvi.

Urin napušta svaki bubreg kroz cijev koja se zove ureteri. Mokraćovode iz oba bubrega korigiraju se u mokraćnu bešiku koja sakuplja i skladišti mokraću. Ureteri prenose urin iz bubrega u mokraćnu bešiku. Uretra je kanal koji nosi mokraću iz bešike i izbacuje je van tela.

Unutrašnja struktura bubrega:

Svaki bubreg je zatvoren u tankom, vlaknastom omotaču zvanom kapsula. Bubrežna arterija dovodi krv u bubreg, zajedno sa azotnim otpadnim materijama. Nakon filtriranja u bubregu, pročišćena krv napušta bubreg kroz bubrežnu venu.

U dijelu bubrega mogu se vidjeti dvije različite regije:

(1) Spoljni, tamni, granularni korteks i (2) unutrašnja, svetlija moždina. Šuplji prostor odakle mokraćovod napušta bubreg naziva se karlica. Svaki bubreg se sastoji od brojnih (oko milion) uvijenih tubula za izlučivanje, poznatih kao nefroni, i sabirnih kanala povezanih sa sićušnim krvnim sudovima. Nefron je strukturna i funkcionalna jedinica bubrega, koja ima tri funkcije – filtraciju, reapsorpciju i sekreciju.

Grupa krvnih kapilara tankih zidova ostaje povezana sa čašastim krajem svakog tubula nefrona. Ove kapilare dovode krv iz tijela u nefron radi filtracije. Mreža kapilara se prostire i preko tubula nefrona. Ove kapilare konačno nose pročišćenu krv u tijelo.

Struktura i funkcija nefrona:

Nefron se sastoji od dugog namotanog tubula i Malpigijevog tjelešca. Tubul nefrona se diferencira na proksimalni uvijeni tubul, Henleovu petlju i distalni uvijeni tubul. Distalni tubul se otvara u sabirni kanal.

Na proksimalnom kraju nefrona nalazi se Malpigijevo tjelešce, koje se sastoji od Bowmanove kapsule i glomerula. Bowmanova kapsula je čašasta struktura sa dvostrukim stijenkama koja okružuje gustu mrežu krvnih kapilara zvanu glomerul.

Proces izlučivanja u nefronu:

Proces izlučivanja se može podijeliti u tri faze - tubularna sekrecija.

Filtracija krvi se dešava pod visokim pritiskom u nefronima bubrega. Krv ulazi u glomerul kroz aferentnu arteriolu (sa širim lumenom) i izlazi kroz eferentnu arteriolu (sa uskim lumenom). Zbog toga krv prolazi kroz glomerul pod pritiskom. To rezultira filtracijom krvi.

Voda i mali molekuli se istiskuju iz zidova kapilara glomerula i Bowmanove kapsule i ulaze u tubul nefrona. Veliki molekuli ostaju u krvi glomerula. Filtrat sadrži vodu, glukozu, soli, ureu, vitamine itd. Zove se glomerularni filtrat.

Selektivna reapsorpcija:

Neki molekuli glomerularnog filtrata se selektivno reapsorbuju u krv. Glomerularni filtrat teče kroz proksimalni izvijeni tubul, Henleovu petlju u obliku slova U i distalni izvijeni tubul. Sadrži mnoge korisne tvari kao što su glukoza, aminokiseline i soli.

Oni se reapsorbuju procesom koji zahteva energiju. Bez reapsorpcije, ovi nutrijenti su mogli biti izgubljeni sa urinom. Filtrat sada sadrži ureu, malo soli i vodu. Reapsorpcija otopljenih tvari u krv povećava koncentraciju vode u filtratu.

Tada se voda procesom osmoze reapsorbuje u krv i uspostavlja se osmotska ravnoteža. Količina vode koja se reapsorbira ovisi o količini viška vode u tijelu i količini otopljenog otpada koji se izlučuje.

Ova reapsorpcija vode iz filtrata radi održavanja ravnoteže vode u tjelesnoj tekućini poznata je kao osmoregulacija. Na taj način bubrezi služe kao organi koji čuvaju vodu. Nakon reapsorpcije iz 180 L filtrata u bubregu, stvara se samo 1-2 L urina.

Neki otpadni proizvodi dušika poput kreatinina i nekih drugih tvari poput kalijevih jona uklanjaju se iz krvi distalnim zavijenim tubulom, a zatim se dodaju urinu. To se zove tubularna sekrecija.

Urin koji se stvara neprestano se skuplja u mokraćnoj bešici. Kako se mokraćna bešika širi, njen pritisak stvara nagon za propuštanjem mokraće kroz uretru. Kako je bešika mišićava, nagon za mokrenjem je pod voljnom nervnom kontrolom.

Zatajenje bubrega i komplet za preživljavanje—hemodijaliza:

Bubrezi mogu biti oštećeni zbog infekcije, ozljede, dijabetesa i ekstremnog krvnog tlaka. Oštećeni bubreg ne može efikasno da ukloni ureu, ione, vodu itd. iz krvi. Ovaj kvar rezultira nakupljanjem toksičnog otpada poput ureje (uremije), što može dovesti do smrti.

Jedan od načina liječenja zatajenja bubrega je korištenje ‘mašine za dijalizu’ koja djeluje kao umjetni bubreg. Ima dugačku cijevnu strukturu napravljenu od celofana suspendovanog u spremniku (dijalizator) svježe dijalizne tekućine (dijaliza). Celofanska cijev je djelomično propusna i stoga omogućava difuziju otopljenih tvari. Tečnost za dijalizu ima istu koncentraciju kao normalna tkivna tečnost, ali nema azotnog otpada i viška soli.

Tokom dijalize, krv pacijenta se vadi iz arterije i hladi na 0°C. Održava se u tečnom stanju dodavanjem antikoagulansa i drugim posebnim tretmanima. Pumpa se kroz mašinu za dijalizu. Ovdje se dušični otpadni proizvodi iz krvi difundiraju u tekućinu za dijalizu. Pročišćena krv se zatim zagrije na tjelesnu temperaturu i pumpa natrag u pacijentovo tijelo kroz venu.

Dijalizator je specifičan za svakog pacijenta kako bi se izbjegle infekcije. Dijaliza putem umjetnog bubrega mora se provoditi u čestim intervalima. Ovaj proces pročišćavanja krvi naziva se hemodijaliza.

Aparat za dijalizu radi kao bubreg osim što se u prvom ne odvija selektivna reapsorpcija.

(1) Pomaže u uklanjanju štetnog otpada, viška soli i vode

(2) Kontroliše krvni pritisak i

(3) Održava ravnotežu soli natrijuma i kalija kod pacijenata čiji su bubrezi otkazali.

Izlučivanje u biljkama:

U poređenju sa životinjama, biljke nemaju dobro razvijen sistem izlučivanja za izbacivanje azotnih otpadnih materija. To je zbog razlika u njihovoj fiziologiji. Stoga biljke koriste različite strategije za izlučivanje.

Otpadni plinoviti materijali koji nastaju tijekom disanja (ugljični dioksid) i fotosinteze (kiseonik) difundiraju kroz puči u lišću i kroz leće u drugim dijelovima biljke. Višak vode isparava uglavnom iz stomata, a također i sa vanjske površine stabljike, plodova itd., tokom cijelog dana. Ovaj proces oslobađanja od viška vode naziva se transpiracija.

Otpadni proizvodi, poput kisika, ugljičnog dioksida i vode, su sirovine za druge ćelijske reakcije. Na taj se način troši višak ugljičnog dioksida i vode. Jedini glavni gasoviti produkt izlučivanja biljaka je kiseonik!

Mnoge biljke pohranjuju organske otpadne proizvode u svoja trajna tkiva koja imaju mrtve ćelije, na primjer, u srcu. Biljke takođe pohranjuju otpad unutar svog lišća ili kore. Ovi otpad se povremeno uklanja kako lišće i kora otpadaju.

Neki od otpadnih proizvoda pohranjuju se u posebne ćelije ili ćelijske vakuole. Različiti otpadni proizvodi kao što su tanini, eterična ulja, gume, smole, itd., nastaju tokom kataboličkih procesa. Listovi čaja, amla i betel orasi (supari) sadrže tanin. Tanini se takođe nalaze u kori drveća.

Listovi mnogih biljaka, poput eukaliptusa, limuna, svetog bosiljka (tulsi), itd., sadrže eterična ulja. Kora narandže i limuna i latice cvijeća poput ruže i jasmina također sadrže ulja. Neki biljni otpad se skladišti kao gusta, bijela tekućina. Možda ste vidjeli da curi bijela tekućina kada iščupate papaju ili smokvu ili listove žutog oleandra (pila kaner). Ova bijela tečnost se zove lateks.

Gume su grupa ljepljivih, vodotopivih otpada koji se nalazi u običnom drvetu gume (babul). Smole su još jedna grupa otpada koji se obično nalazi u stabljikama četinara (npr. bor, jela).

Alkaloidi su grupa toksičnih otpadnih proizvoda. Ali neki od njih su nam korisni. Kinin i morfin su lijekovi koji se dobivaju iz alkaloida pohranjenih u kori cinkone i cvjetovima opijumskog maka. Kofein koji se nalazi u sjemenkama kafe i nikotin u listovima duhana također su alkaloidi.

Organske kiseline, koje bi mogle biti štetne za biljke, često se kombinuju sa viškom katjona i talože se kao netopivi kristali koji se mogu sigurno pohraniti u biljnim stanicama. Kristali kalcijum oksalata nakupljaju se u nekim gomoljima poput jam (zamikand).

Vodene biljke gube većinu svog metaboličkog otpada direktnom difuzijom u vodu koja ih okružuje. Kopnene biljke izlučuju dio otpada u tlo oko sebe.


Glavni dijelovi ljudskog probavnog sistema (sa dijagramom)

Predvorje je prostor u obliku proreza koji je izvana omeđen usnama i obrazima, a iznutra desnima i zubima.

(b) Usna šupljina (usna šupljina):

To je unutrašnji dio usta koji ima sljedeće dijelove.

Krov usne šupljine (bukalna šupljina) naziva se nepce. Prednji dio nepca je poznat kao tvrdo nepce koje nosi poprečne izbočine, rugae. Stražnji dio nepca je gladak i naziva se meko nepce. Stražnji slobodni dio mekog nepca slobodno visi kao mali preklop, uvula.

(ii) Jezik. Jezik je pričvršćen za dno usta naborom koji se naziva jezični frenulum. Obrnuta brazda u obliku slova V, koja se naziva sulcus terminalis, dijeli gornju površinu jezika na prednji oralni dio i stražnji faringealni dio. Vrh sulcus terminalis štrči unatrag i označen je malom središnjom jamicom, nazvanom foramen caecum.

Gornja površina jezika ima četiri vrste papila (male izbočine).

(a) Vallate papile ili Circumvallate papillae obično imaju oko 8 do 12. Svaka vallate papilla sadrži do 100 okusnih pupoljaka. Ove papile su najveće od četiri tipa papila.

(b) Filiformne papile su najmanji i najbrojniji od četiri tipa. Konusne su. Nalaze se uglavnom blizu središta i većine gornje površine jezika. Ove papile sadrže taktilne (dodirne) receptore, ali ne i okusne pupoljke.

(c) Fungiformne papile su mnogo manje brojne od filiformnih papila. Zaobljene su, ali manje od vala, ali veće od filiformnih papila. Najbrojniji su u blizini vrha jezika. Svaka gljivična papila sadrži oko pet okusnih pupoljaka.

(d) Folijatne papile nisu razvijene na ljudskom jeziku. Oni su nalik listovima i nalaze se na bočnim stranama osnove jezika. Na svakoj granici ima četiri ili pet vertikalnih nabora. Njihovi okusni pupoljci degeneriraju u ranom djetinjstvu.

Ljudski jezik ima četiri područja ukusa (slatko, slano, kiselo i gorko). Područja slatkog i slanog se mogu preklapati.

Funkcije jezika:

Jezik se ponaša kao pomoćni organ za varenje.

(i) Pomaže u žvakanju hrane.

(ii) pomaže pri gutanju hrane,

(iii) Djeluje kao četkica za čišćenje zuba,

(iv) igra ulogu u govoru,

(v) To je organ ukusa.

Muškarci imaju difiodont (dva seta zuba – mliječni ili de­ciduous i trajni), tekodont (zubi su ugrađeni u utičnice kostiju vilice) i heterodontne zube (različite vrste zuba). Prisutne su četiri vrste zuba – sjekutići, očnjaci, pretkutnjaci i kutnjaci.

Obično su specijalizovani za rezanje.

Leže odmah iza sjekutića. Koriste se i za rezanje hrane.

To se nazivaju obrazni zubi koji su široki, jaki zubi koji se lome i stisnu. Treći kutnjaci kod ljudi se nazivaju umnjaci. Potonji su vesti­galni kod ljudskih bića.

Mliječnih ili mliječnih ili privremenih zuba ima po 20 u broju 10 u gornjoj i donjoj vilici. Mliječni zubi počinju da izbijaju kada dijete napuni oko 6 mjeseci i svi bi trebali biti prisutni do kraja 24 mjeseca. Stalni zubi počinju da zamenjuju mliječne u 6. godini života. Ovi zubi imaju 32 godine i obično su kompletni za 18-25 godina.

Mliječni zubi čovjeka imaju 8 sjekutića, 4 očnjaka i 8 kutnjaka (premolari su odsutni). Kutnjaci mliječnih zuba se odvajaju i njihovo mjesto zauzimaju premolari trajnih zuba. Stalni zubi su 8 sjekutića, 4 očnjaka, 8 pretkutnjaka i 12 kutnjaka. Tako je 12 zuba (8 pretkutnjaka i 4 kutnjaka) monofiodont (zubi koji rastu samo jednom u životu). Stomatološke formule mliječnih i trajnih zuba ljudi su date u nastavku.

Mliječni zubi Trajni zubi:

Dentalna formula daje polovinu ukupnog broja zuba. Ovo se udvostručuje da bi se odredio puni broj.

Tipičan zub se sastoji od tri regije krune – dijela koji strši iznad desni, vrata – dijela koji je okružen desnim i korijena – dijela koji je ugrađen u kost.

Sjekutići i očnjaci imaju jedan korijen, gornji prvi pretkutnjaci imaju dva korijena, a gornji drugi pretkutnjaci i donji pretkutnjaci obično imaju samo jedan korijen. Gornji kutnjaci imaju tri korijena, a donji kutnjaci dva korijena.

Ljudski zub se sastoji od sljedećih dijelova:

To je najteža supstanca ljudskog tijela. Prekriva dentin u kruni.

Ima brojne fine kanaliće koji radijalno prolaze od pulpne šupljine prema gleđi.

Pokriva korijen zuba.

Sastoji se od kolagenih vlakana i prekriva cement. Učvršćuje zub u svojoj čauri.

Dentin zatvara pulpnu šupljinu koja sadrži masu ćelija, krvnih sudova i nerava koji čine pulpu. Kroz korijen zuba prolaze uski produžeci šupljine pulpe, koji se nazivaju korijenski kanali.

Osim ćelija vezivnog tkiva pulpe i parodontalne membrane i cementocita u cementu, postoje dvije glavne vrste ćelija. To su odon­toblasti koji formiraju dentin i ameloblasti koji formiraju caklinu.

II. Pharynx (Throat):

It is divided for descriptive purposes into three parts the nasopharynx, oropharynx and laryngopharynx.

(i) The nasopharynx (nasal part of the pharynx) lies behind the nasal cavities, above the soft palate. The Eustachian tube (also called auditory tube) connects nasopharynx with the middle ear.

(ii) The oropharynx (oral part of the pharynx) lies behind the oral cavity (buccal cavity). The nasopharynx and oral cavity open into the oropharynx which is a com­mon passage for both food and air.

(iii) The laryngopharynx (laryngeal part of the pharynx), is the most inferior portion of the pharynx. It leads into the oesophagus behind and into the larynx in front.

The pharynx is a common passage for food and air.

The lymphatic tissues of the pharynx and oral cavity are arranged in a ring like manner, which are collectively called Waldeyer’s ring (- Waldeyer’s lymphatic ring).

The ring mainly consists of the following:

(i) Pharyngeal Tonsil is attached to pharynx. In children pharyngeal tonsil may become enlarged and is then referred to as the adenoids. The resulting swelling may be a cause of obstruction to normal breathing.

(ii) Tubal Tonsils are situated around the Eustachian tube.

(iii) Palatine Tonsils are attached to the palate. The palatine tonsils are often in­fected (tonsillitis) leading to sore throat. Such enlarged tonsils may become a focus of infection and their surgical removal (ton­sillectomy) becomes necessary.

(iv) Lingual Tonsil is attached to pharyngeal part of the tongue.

All these lymphoid tissues are active in production of immunoglobin. A which forms an important part of our immune system.

III. Oesophagus:

The human oesophagus or food pipe is about 25 cm long. It lies behind the trachea and the heart. It comprises three parts: cervical part in the neck, thoracic part in the thorax and abdominal part in the abdomen. The oesophagus passes through the diaphragm and opens into the stomach.

The oesophagus transfers food from the pharynx to the stomach.

IV. Stomach (= Gaster):

It is the wid­est organ of the alimentary canal. The stomach is J-shaped organ. The lesser cur­vature lies on the posterior surface of the stomach. The greater curvature is on the anterior surface of the stomach.

The fold of peritoneum which attaches the stomach to the posterior abdominal wall extends be­yond the greater curvature. This is called the greater omentum which stores fat. The stomach has four parts: cardiac part, fundus, body and pyloric part.

(i) Cardiac Part (= cardia):

It is so called because it is present near the heart. The gastro esophageal sphincter (= car­diac sphincter) lies in the opening between oesophagus and stomach. It is not a true valve. It is a functional sphincter.

It is commonly filled with air or gas.

It is the main part of the stomach.

(iv) Pyloric Part (Pylorus):

It is the posterior part of the stomach.

The pyloric part is divided into the pyloric antrum and the pyloric canal. The latter opens into the duodenum. The pyloric sphincter guards the opening between the stomach and the duodenum and periodically permits partially digested food to leave the stomach and enter the duodenum.

Functions of the Stomach:

It stores food for some time. It churns and breaks up food and mixes the pieces with gastric juice. Partial digestion of food (proteins and fats) takes place here. It produces Castle’s intrinsic factor (a glycoprotein) which is necessary for the absorption of vitamin B12 to be absorbed in the intestine.

It secretes pro-enzymes— pepsi­nogen and pro-rennin and enzymes gastric lipase and gastric amylase. It also secretes gastrin (hormone). Alcohol, aspirin, some lipid-soluble drags, moderate amounts of sugar and water are absorbed by the stomach wall.

V. Small Intestine:

It is so named because it has small diameter. Length is correlated with the height of the individual but not with weight. It is the longest part of the alimentary canal. It is about 6.25 metres long. It comprises three parts duodenum, jejunum and ileum.

It is so called because it is about as long as the breadth of 12 fingers. It is about 25 cm long and is the shortest, widest part of the small intestine. It is somewhat С-shaped. The hepatopancreatic ampulla (ampulla of Vater) opens into the duodenum. This ampulla receives both bile duct from the liver and main pancreatic duct from the pancreas. Iron is mainly absorbed in the duodenum.

It has a diameter of about 4 cm. Its wall is thick. It is redder and more vascular. It is the middle part of the small intestine and is about 2.5 metres long.

It has a diameter of 3.5 cm. Its wall is thinner than that of the jejunum. It is the longest part of small intestine and is about 3.5 metres long. Both the jejunum and ileum are greatly coiled. They are suspended by mesentery.

Small nodules of lymphatic tissue can be seen along the entire length of the small intestine. In some places, particularly along the ileum, these nodules are clustered together in groups called Peyer’s patches or lymph nodules.

Peyer’s patches are a distinguishing characteristic of the ileum, which produce lymphocytes (type of WBCs). Finger-like projec­tions of the mucosa, the villi are present in the small intestine. Villi are absent over the Peyer’s patches.

The villi increase the surface of the small intestine. Each villus is covered with epithelium and contains a lymph capillary (lacteal) and blood capillaries. The entire small intestine has circular folds of the mucous membrane, the plicae circulares (‘Valves’ of Kerkring). These folds are more prominent in the jejunum. They further increase the absorptive surface considerably.

Functions of the small intestine:

The small intestine completes digestion of proteins, carbohydrates, fats and nucleic acids. It absorbs nutrients into the blood and lymph. It secretes certain hormones such as cholecystokinin, secretin, enterogastrone, duocrinin, enterocrinin and villikinin. It also secretes digestive enzymes.

VI. Large Intestine:

Its diameter is larger than that of the small intestine. Hence it is so named. It is about 1.5 metres long and is divisible into three parts caecum, colon and rectum.

(i) Caecum and vermiform appendix:

The caecum is a pouch-like structure which is about 6 centimetres. The vermiform appendix (commonly called the appendix) is an outgrowth of the caecum.

It is a slightly coiled blind tube of about 8 centimetres long. Its wall contains prominent lymphoid tissue. Appendix is thought to be vestigial. The inflam­mation of vermiform appendix is called appendicitis. The caecum and appendix are well developed in herbivorous mammals like rabbits.

The caecum leads into the colon, which is divided into four regions the ascending, transverse, descending and sigmoid colon (pelvic colon is its former name). Ascending colon is the shortest part of the colon. The colon has three longitudinal bands called taeniae coli and small pouches called haustra (sing, haustrum).

The sigmoid colon opens into the rectum. The rectum comprises the last 20 centimetres of the digestive tract and terminates in the 2-centimetre long anal canal. The opening of the anal canal is called anus.

The anus has an internal anal sphincter composed of smooth muscle fibres and an external anal sphincter comprised of striped (voluntary) muscle fibres. Structures formed due to enlargements of veins of anal columns in anal canal as well as anus are called haemorrhoids or piles.

Functions of the large intestine:

The chief functions of the large intestine are the absorption of water and the elimination of solid wastes. However, moderate quantities of vitamin К and vitamin В complex are manufactured by bacteria in the large intestine.

Histology of Human Gut (Alimentary Canal):

The wall of alimentary canal consists of four basic layers.

From the outer surface inward to the lumen (cavity) the layers are as follows:

1. Visceral peritoneum (= Serosa):

It is made up of squamous epithelium and areolar connective tissue. It is continuous with the mesentery. Since the oesophagus lies outside the coelom, its outer wall is not covered by peritoneum (serosa) but by an irregular coat of dense elastic fibrous connective tissue called adventitia external ( = external adventitia).

2. Muscularis (Muscular coat):

It is composed of outer longitudinal and inner cir­cular muscle fibres. In the stomach an additional layer of oblique muscle layer is found inner to the circular muscle fibres.

These muscle fibres are un-striped (smooth). In between the longitudinal and circular muscle fibres there is a network of nerve cells and parasym­pathetic nerve fibres, called the Auerbach’s plexus (= myenteric plexus). The Auerback s plexus controls peristalsis.

It consists of loose connective tissue richly supplied with blood and lymphatic vessels and in some areas with glands. Another network of nerve cells and sympathetic nerve fibres, called Meissner’s plexus (= sub-mucosal plexus) is present be­tween the muscular coat and the mucosa. This plexus controls the secretion of intestinal juice.

4. Mucosa (= Mucous membrane):

It is the innermost layer lining the lumen of the alimentary canal. It is so named because it secretes mucus to lubricate the inner lining of the gut. This layer forms irregular folds (rugae) in the stomach.

Mucosa is composed of three layers:

(i) The muscular is mucosa consists of outer longitudinal and inner circular muscle fibres, both are un-striped.

(ii) The lamina propria consists of loose connective tissue, blood vessels, glands and some lymphoid tissue.

(iii) The epithelium forms gastric glands in stomach, and villi and intestinal glands in small intestine.

In upper one third of the oesophagus both Auerbach and Meissner’s plexuses are absent.

Part # 2. Digestive Glands

I. Salivary Glands (Fig. 16.10):

Salivary glands discharge their secretion into the oral cavity. In man, the salivary glands are three pairs— parotid, sublingual and submandibulor glands,

(i) Parotid glands. These are the largest salivary glands which are situated near the ears. Their ducts open into the oral cavity near the upper second molars. The duct of parotid gland is called Stenson’s duct,

(ii) Sublingual glands. These are smallest salivary glands which are located beneath the tongue and their ducts called sublingual ducts or ducts of Rivinus which open into the floor of the oral cavity,

(iii) Submandibular (also called sub maxillary) glands.

These are me­dium sized salivary glands which are located at the angles of the lower jaw. Their ducts open into the oral cavity near the lower central incisors.

The duct of submandibular gland is called Wharton’s duct. The parotid salivary glands secrete much of salivary amylase or a-amylase (= ptyalin). Sub-lingual and sub-mandibular salivary glands secrete salivary amylase and mucus. Salivary amylase is absent in herbivores.

The disease mumps is a viral infection that may involve one or both parotid salivary glands. The fluids secreted by the salivary glands constitute saliva. Saliva is slightly acidic (pH 6.8). About 1,000-1500 ml of saliva is secreted per day.

Saliva is a mixture of water and electrolytes (Na + , K + , CI – , HC03 – ), derived from blood plasma, mucus and serous fluids (watery constituent of saliva), and salivary amylase or ptyalin (enzyme) and lysozyme (antibacterial agent). Ions of thyocyanate are also present in the saliva.

II. Gastric Glands (Fig. 16.11):

These are numerous microscopic, tubular glands formed by the epithelium of the stom­ach. Gastric glands have three major types of cells.

(i) Chief cells or Peptic cells (= Zymogenic cells) are usually basal in location and secrete gastric digestive enzymes as pro-enzymes or zymogens pepsinogen and pro-rennin.

The chief cells also produce small amount of gastric amylase and gastric lipase. Gastric amylase action is inhibited by the highly acid condition. Gastric lipase con­tributes little to digestion of fat. Pro-rennin is secreted in young mammals. It is not secreted in adult mammals.

(ii) Oxyntic cells (= Parietal cells) are large and are most numerous on the side walls of the gastric glands. They are called oxyntic cells because they stain strongly with eosin. They are called parietal cells as they lie against the basement membrane. They secrete hydrochloric acid and Castle intrinsic factor.

(iii) Mucous cells (= Goblet cells) are present throughout the epithelium and secrete mucus.

The secretions of these cells form gastric juice with pH 1.5-2.5 (very acidic). Infant’s gastric juice pH is 5.0. About 2,000-3,000 ml of gastric juice is secreted per day. The gastric juice contains two pro-enzymes— pepsinogen (pro-pepsin) and pro-rennin, and enzymes gastric lipase and gastric amylase, and mucus and hydrochloric acid.

The epithelium of gastric glands also has the following two types of cells:

(i) Endocrine cells are usually present in the basal parts of the gastric glands. These are argentaffin cells and Gastrin cells (= G-cells). Argentaffin cells produce serotonin (its precursor is 5-hydroxytryptamine, 5-HT), somatostatin and histamine. Gastrin Cells (= G-cells) are present in the pyloric region and secrete and store the hormone gastrin.

Serotonin is a vasoconstrictor and stimulates the smooth muscles. Somatostatin suppresses the release of hormones from the digestive tract. Histamine dilates the walls of blood vessels. Gastrin stimulates the gastric glands to release the gastric juice.

(ii) Stem cells are undifferentiated cells that are also present in the epithelium of the gastric glands. They multiply and replace other cells. They increase in number when the gastric epithelium is damaged (e.g., when there is a gastric ulcer) and play an important role in healing.

III. Liver (= Hepar):

It is the largest gland of the body. The liver lies in the upper right side of the abdominal cavity just below the diaphragm. It is heavier in males than females. In males it generally weighs 1.4-1.8 Kg and in females 1.2-1.5 Kg.

The liver is divided into two main lobes— right and left lobes separated by the falciform ligament. The latter is a membrane that is continuous with the peritoneum. The right lobe of the liver is further differentiated into right lobe proper, a quadrate lobe and a caudate lobe on the posterior surface.

Internally, the structural and functional units of liver are the hepatic lobules containing hepatic cells arranged in the form of cords. Each lobule is covered by a thin connective tissue sheath called the Glisson’s capsule. Glisson’s capsule is the characteristic feature of mammalian liver. The mammalian liver also contains Kupffer cells that are phagocytic cells and eat worn out WBCs, RBCs and bacteria.

Fat storage cells are also present. The plates of liver cells are separated from the endothelial lining of the sinusoid by a narrow perisinusoidal space of Disse. Some fat cells may also be seen in the space of Disse. Blood vessels and bile ductules present in the portal canals are surrounded by a narrow space of Mall.

Bile is secreted by the liver cells (hepatocytes). Bile enters bile canaliculi or bile capillaries (a net work of tubular spaces between the liver cells). The bile canaliculi empty into small Hering’s canals walled by cuboidal epithelium. These canals pour bile into interlobular bile duct (=bile ductule) walled by columnar epithelium.

A pear shaped sac like structure is attached to the posterior surface of the liver by connective tissue. It stores bile secreted by the liver. Rat and horse do not have gall bladder.

The right and left hepatic ducts join to form the common hepatic duct. The latter joins the cystic duct which arises from the gall bladder. The cystic duct and common hepatic duct join to form bile duct which passes downwards posteriorly to join the main pancreatic duct to form the hepatopancreatic ampulla (= ampulla of Vater).

The ampulla opens into the duodenum. The opening is guarded by the sphincter of Oddi. The sphincter of Boyden surrounds the opening of the bile duct before it is joined with the pancreatic duct.

Blood Supply (Fig. 16.15):

Blood enters the liver from two sources. From the hepatic artery it gets oxygenated blood and from the hepatic portal vein it receives deoxygenated blood. Blood in the hepatic artery comes from the aorta. Blood in the hepatic portal vein comes directly from the intestine containing newly absorbed nutrients. The hepatic portal vein also brings blood from the spleen to the liver. Liver has high power of regeneration.

Bile is a watery greenish fluid mixture containing bile pigments, bile salts, cholesterol and phospholipids.

Bile serves the following functions:

(i) Neutralization of HCI:

Its sodium bicarbonate neutralizes HC1 of chyme (semi-fluid food that comes from the stomach).

Sodium glycocholate and sodium taurocholate break the large fat droplets into the smaller ones. This process is called emulsification.

(iii) Absorption of fat and fat-soluble vitamins:

Its salts help in the absorption of fat (fatty acids and glycerol) and fat-soluble vitamins (A, D, E and K) in the small intestine.

Bile pigments (bilirubin and biliverdin) are excretory products.

(v) Prevention of Decomposition:

Bile is alkaline hence it prevents the decomposition of food by preventing the growth of bacteria on it.

(vi) Stimulation of Peristalsis:

Bile increases peristalsis of the intestine.

(vii) Activation of Lipase:

Bile contains no enzyme but activates the enzyme lipase.

Obstruction of the hepatic or bile duct by gall stones or due to other causes is common. Jaundice occurring as a result of such obstruction is called obstructive jaundice. In this disease the bile is absorbed into the blood instead of going to the duodenum and cause yellowing of eyes and skin.

IV. Pancreas (Fig. 16.12 & 16.16):

The pancreas is soft, lobulated, greyish- pink gland which weighs about 60 grams. It is about 2.5 centimetres wide and 12 to 15 centimetres long, located posterior to the stomach in the abdominal cavity.

External Structure of Pancreas:

The Pancreas comprises the head, neck, body and tail. The head lies in the curve of the duodenum, the neck follows the head, the body behind the stomach and the tail reaches the spleen lying in front of the left kidney.

The main pancreatic duct (= duct of Wirsung) is formed from smaller ducts within the pancreas. The main pancreatic duct opens into the hepatopancreatic ampulla (= ampulla of Yater). An accessory pancreatic duct (= duct of Santorini) is also present in the pancreas and opens directly into the duodenum.

Internal Structure of Pancreas:

It consists of two parts: exocrine part and endocrine part.

The exocrine part of the pancreas consists of rounded lobules (acini) that secrete an alkaline pancreatic juice with pH 8.4. About 500-800 ml of pancre­atic juice is secreted per day. The pancreatic juice is carried by the main pancreatic duct into the duodenum through the hepatopancreatic ampulla.

The accessory pancreatic duct di­rectly pours the pancreatic juice into the duodenum. The pancreatic juice contains sodium bicarbonate, three pro-enzymes trypsinogen, chymotrypsinogen and procarboxypeptidase and some enzymes such as elastase, pancreatic a-amylase, DNase, RNase and pancre­atic lipase. The pancreatic juice helps in the digestion of starch, proteins, fats and nucleic acids.

The endocrine part of the pancreas consists of groups of islets of Langerhans. The human pancreas has about one million islets. They are most numerous in the tail of the pancreas. Each islet of Langerhans consists of the following types of cells which secrete hormones to be passed into the circulating blood.

(a) Alpha cells (= α-cells):

These cells are more numerous towards the periphery of the islet and constitute 15% of the islet of Langerhans. They produce glucagon hormone which converts glycogen into glucose in the liver. Thus glucagon is diabetogenic hormone.

These cells are more numerous towards the middle of the islet and constitute 65% of the islet of Langerhans. They produce insulin hormone which converts glucose into glycogen in the liver and muscles. Deficiency of insulin causes dia­betes mellitus.

(c) Delta cells (= δ-cells):

These cells are also found towards the periphery of the islet of Langerhans and constitute 5% of the islet of Langerhans. They secrete somatostatin (SS) hormone which inhibits the secretion of glucagon by alpha cells and secretion of insulin by beta cells. This hormone also slows absorption of nutrients from the gasrointestinal tract.

Somatostatin secreted by argentaffin cells of gastric and intestinal glands suppresses the release of hormones from the digestive tract. Somatostatin is also secreted by the hypo­thalamus of the brain where it inhibits the release of growth hormone (somatotropin) by the ante­rior lobe of pituitary gland. That is why it is also called growth inhibitory hormone.

(d) Pancreatic polypeptide cells (= PP cells or F-cells):

Apart from the three main types of cells described above, the PP cells are also present in the pancreas, which constitute 15% of the Islet of Langerhans. These cells secrete pancre­atic polypeptide (PP) which inhibits the release of pancreatic juice. Thus the pancreas performs two main func­tions i.e., secretion of pancreatic juice which contains digestive enzymes and production of hor­mones.

V. Intestinal Glands (Fig. 16.17):

These are formed by the surface epithelium of the small intestine. These are of two types: crypts of Lieberkuhn and Brunner’s glands.

(i) The crypts of Lieberkuhn are simple, tubular structures which occur through­out the small intestine between the villi. They secrete digestive enzymes and mucus. The mucus is secreted by the goblet cells (= mucous cells) whereas water and electrolytes are secreted by enterocytes present on the intestinal crypts. These crypts have at the base paneth cells and argentaffin cells.

(a) Paneth cells are found particularly in the duodenum. These cells are present in the bottom of crypts of Lieberkuhn. These cells are rich in zinc and contain acidophilic granules. The function of these cells is not certain but there is evidence that they secrete lysozyme (antibacterial substance). Paneth cells are also capable of phagocytosis.

(b) Argentaffin cells synthesize secretin hormone and 5-hydroxytryptamine (5-HT).

(ii) The Brunner’s glands are found only in the duodenum and are located in the submucosa. They secrete a little enzyme and mucus. The mucus protects the duodenal wall from getting digested. Digestion of most of nutrients takes place in the duodenum under the action of various enzymes. The Brunner’s glands open into the crypts of Lieberkuhn.

The secretion of intestinal glands is called intestinal juice or succus entericus with pH 7.8. About 2,000-3,000 ml of intestinal juice is secreted per day. The intestinal juice contains many enzymes— maltase, isomaltase, sucrase, lactase, α- dextrinase, enterokinase, aminopeptidases, dipeptidases, nucleotidases, nucleosidases and intestinal lipase.

In addition to the glands mentioned above the entire alimentary canal has mucous glands that produce mucus. The mucus lubricates the digestive tract and food. Human digestive system has many accessory organs. Tongue, salivary glands, liver, gall bladder and pancreas are some important human accessory digestive organs.

Swallowing or Deglutition (Fig. 16.18):

The food is tasted in the oral cavity and mixed with saliva. Tongue manipulates food during chewing and mixing with saliva. This collection of food, the bolus (mass of food) is then pushed inward through the pharynx into the oesophagus.

This process is called swallowing or deglutition. Swallowing involves coordinated activity of tongue, soft palate, pharynx and oesophagus.

Swallowing is conveniently divided into three stages:

(i) The Voluntary stage:

The tongue blocks the mouth. The bolus is forced to move from the oral cavity into the pharynx (oropharynx). This represents the volun­tary stage of swallowing.

(ii) The Pharyngeal stage:

With the passage of the bolus into the pharynx, the invol­untary pharyngeal stage of swallowing begins. The palate closes off the nose and the epiglottis seals off the glottis of larynx. Thus breathing is temporarily interrupted. The bolus is passed from the pharynx into the oesophagus.

(iii) The Oesophageal stage:

This also represents the involuntary stage of swallowing. The bolus passes through the laryngopharynx and enters the oesophagus in 1 to 2 seconds. The respiratory passage then reopens and breathing resumes. Swallowing is controlled by a swallowing centre located in the medulla oblongata and lower pons varolii of the brain.

During the oesophageal phase of swallowing, food is pushed through the oesophagus by involuntary muscular movements called peristalsis.

Peristalsis is produced by involuntary contraction of circular muscles in the oesophagus lying just above and around the top of the bolus and simultaneous contraction of the longitudinal muscles lying around the bottom of and just below the bolus.

Contraction of the longitudinal muscles shortens the lower part of the oesophagus, pushing its walls out­ward so that it can receive the bolus. After this circular muscles of the oesophagus relax. The contractions are repeated in a wave that moves down the oesophagus, pushing the food towards the stomach. There is least peristaltic movement in the rectum of human being.


Common COVID-19 Vaccine Myths Explained

Even if you understand the scientific process, trust medical experts and know how important vaccines are for fighting infectious diseases, you might still have some questions or concerns about the new COVID-19 vaccines – especially with so many rumors floating around online.

Klinika Cleveland je neprofitni akademski medicinski centar. Oglašavanje na našoj web stranici podržava našu misiju. Ne podržavamo proizvode ili usluge klinike koja nije Cleveland. Politika

It’s normal and healthy to have questions, says Thaddeus Stappenbeck, MD, PhD, Chairman of the Department of Inflammation and Immunity at Cleveland Clinic’s Lerner Research Institute.

“These are new therapeutics and it’s totally reasonable to be asking constructive questions with an open mind,” he reassures.

That said, it’s also important to seek out trusted sources of information. Here, Dr. Stappenbeck helps set the record straight on some common questions, concerns and myths that have emerged about COVID-19 vaccines.

Myth 1: We can’t trust COVID-19 vaccines because they were rushed.

The first vaccines for COVID-19 do involve new technology, and they were developed in record time. But it’s not because there were shortcuts in the process.

The new technology at the center of Pfizer’s and Moderna’s COVID-19 vaccines is called messenger RNA, or mRNA. While this is the first time it’s being widely used in a vaccine for the public, researchers have actually been working on this vaccine strategy for more than three decades.

“It was a lucky thing that the technology has been robustly developed quite well over the last few years and tested in several animal models of infection, so we knew that it was safe and worked quite well in these animal models,” Dr. Stappenbeck says.

“When COVID-19 came around, this was an obvious opportunity to use this novel technology, and vaccine developers were poised to do it.”

The companies put their vaccines through rigorous clinical trials involving tens of thousands of volunteers. In the U.S., the Food and Drug Administration requires them to follow up with volunteers for up to two years after receiving the vaccines to make sure they are safe and effective. Because of how prevalent COVID-19 is, it only took a few months for the clinical trials to collect enough data to make an initial evaluation. The FDA, as well as an independent panel of vaccine experts, closely scrutinized the data from those trials and deemed Pfizer’s and Moderna’s vaccines safe and effective for emergency use. Similar independent panels in several other countries are in agreement.

Myth 2: The vaccine will give me COVID-19.

Vaccines prime your immune system to recognize and fight off a disease, but they don’t actually cause an infection.

The first two COVID-19 vaccines that are available in the U.S. contain a strand of genetic material called mRNA. When the mRNA enters your cells, it instructs them to make a piece of the “spike” protein that’s present on the coronavirus that causes COVID-19. Those protein pieces don’t actually harm your body, but they do trigger your immune system to mount a response to fight them off.

You might have some fatigue, muscle aches, a headache or a fever after you get the vaccine. That’s normal with any vaccine – it’s a sign that your immune system is responding.

Myth 3: We don’t know what’s in these vaccines.

Both Pfizer and Moderna have published the ingredient lists for their vaccines. In addition to the star ingredient, the COVID-19 mRNA for the spike protein, both vaccines contain lipids (fats) that help deliver the mRNA into your cells and a few other common ingredients that help maintain the pH and stability of the vaccine. Despite theories circulated on social media, they do not contain microchips or any form of tracking device.

Myth 4: These vaccines will alter my DNA.

The vaccines use mRNA to instruct our cells to make a piece of the coronavirus’s hallmark spike protein in order to spark an immune system response. Once the mRNA does that, our cells break it down and get rid of it.

“Messenger RNA is something that’s made from DNA, but it’s not designed to integrate with our DNA, and it doesn’t permanently change our genome and who we are in any way,” Dr. Stappenbeck says.

Myth 5: I already had COVID-19, so I won’t benefit from the vaccine.

We don’t yet know how long natural immunity to COVID-19 lasts, Dr. Stappenbeck says. Right now, it seems that getting COVID-19 more than once is not common, but there are still many questions that remain unanswered. Experts say that, even if you’ve had COVID-19, it would still be appropriate for you to get the vaccine to make sure you’re protected.

Myth 6: Since COVID-19’s survival rate is so high, I don’t need a vaccine.

It’s true that most people who get COVID-19 are able to recover. But it’s also true that some people develop severe complications. So far, more than 1.7 million people around the world have died from COVID-19 – and that doesn’t account for people who survived but needed to be hospitalized. Because the disease can damage the lungs, heart and brain, it may also cause long-term health problems that experts are still working to understand.

There’s another reason to consider getting the vaccine: It protects those around you. Even if COVID-19 doesn’t make you very sick, you could pass it on to someone else who might be more severely affected. Widespread vaccination protects populations, including those who are most at risk and those who can’t be vaccinated. It will be important for ending the pandemic.

Myth 7: Once I get the vaccine, I won’t have to wear a mask or worry about social distancing.

Even if you get the vaccine, you should continue to wear a mask around others, wash your hands and practice physical distancing. Za to postoji nekoliko razloga. The first is that both of the authorized vaccines require two doses given three to four weeks apart to achieve the best possible immunity.

When you get your first shot, you don’t become immediately immune. “It takes at least a week to 10 days for your body to begin to develop antibodies, and then those antibodies continue to increase over the next several weeks,” Dr. Stappenbeck says.

The second is that these vaccines were developed and tested for their ability to prevent severe illness and death from COVID-19. It’s not clear whether they also protect against asymptomatic infection and spread.

“There will be ongoing studies to evaluate this question, but it will be some time before we actually know,” Dr. Stappenbeck says. “So after you get the vaccine, you should still take steps to protect other people who haven’t been vaccinated yet.”

Myth 8: Now that we have vaccines, the pandemic will be over very soon.

“I would love to say that we’re going to flip a switch and everything’s going to be back to normal, but it’s actually going to take a long time for us to be able to vaccinate an adequate number of people to where we’ll start to see the cases really dropping,” Dr. Stappenbeck explains.

In order to achieve what’s called herd immunity – the point at which the disease is no longer likely to spread – about 70% of the population will need to have been vaccinated or infected, he says. But the companies that make these vaccines can only make so many at a time. So the vaccines will be distributed in phases, with priority given to people with greatest need. They may not be widely available to the general public until several months into 2021.

For now, we should all continue to do our part to help slow the spread of the virus, including wearing a mask, washing our hands and physical distancing.

If you have more questions about the vaccine, talk with your trusted healthcare provider or look to reliable sources like the Centers for Disease Control and Prevention or the World Health Organization.

Myth 9: The vaccine will cause infertility.

Because the COVID-19 vaccines do not contain the live virus (remember, it’s an mRNA vaccine), they are not thought to cause increased risk of infertility, first or second trimester loss, still birth or congenital anomalies. Additionally, there is no evidence to suggest that the vaccine is a risk to a breastfeeding baby.

Klinika Cleveland je neprofitni akademski medicinski centar. Oglašavanje na našoj web stranici podržava našu misiju. Ne podržavamo proizvode ili usluge klinike koja nije Cleveland. Politika


What is the difference between a rat and a human digestive system?

There are several similarities between the digestive system of a rat and a human as far as location and function are concerned. Both mammals possess the three main areas of the digestive system: salivary glands, the oral cavity, and the abdominal cavity. Each of these is subdivided into specific organs.

Digestion, by definition, is the process by which food substances are chemically altered into forms of energy where they can be absorbed through cell membranes.

Because a rat's digestive tract is so similar to that of a human, it is fair to say that they function in similar ways.

An animal's diet is revealed by its dentition pattern. This refers to the types of teeth the animal has, the number of teeth, and how they are arranged. There are three main types of dentition patterns: herbivourous, carnivorous, and omniverous. Rats and humans are both omnivores, meaning they eat meat and vegetation. Rats, however, need to chew more rough food, like tree bark, and in domestic rats, chew toys. This is because their front incisor teeth would, if left to grow freely with nothing to wear it down, would grow through the rodents jaw. This of course, would never happen with humans. Human teeth stop growing after they reach a certain point.

Another major difference between the rat and human digestive tract, aka the alimentary canal, is the fact that while we as humans have gall bladders, rats do not. Instead of a gall bladder, rats have a bile duct (ductus choledochus) which is formed from several tubes from the liver. the various lobes of the liver unite to form this tube (the bile duct) and this allows the transport of bile into the duodenum.

Also, because rats do not have gall bladders, they are more apt to graze constantly throughout the day, which is why (if you have a pet rat--though i doubt this..) you are not supposed to just continually feed them throughout the day. Because they do not have a gene to trigger a feeling of fullness, rats would (along with other rodents, such as guinea pigs, hamsters and mice) literally eat themselves to death.

And finally, because i have to finish a lab report (on a rat dissection no doubt)..when the food enters the caecum (latin spelling of the word..it can also be spelled cecum!) the nutrients is then absorbed. Many anumanls, including man, have a short veriform appendix at the end of the cecum, this is absent in the rat. Oh and rats do not have uvula (i do not know if i said that already) but its true (haha i are dork!)


Pogledajte video: PRIRODNO LEČENJE BOLESTI BUBREGA! Prof. dr Mihajlović (Februar 2023).