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Word bloed as 'n orgaan beskou?

Word bloed as 'n orgaan beskou?


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Dit bestaan ​​ongeveer 7 persent van liggaamsgewig.

Per definisie bestaan ​​orgaan uit verskeie weefsels. Bloed is 'n vloeistof, 'n sirkulerende weefsel.

Daarom kan ons hierdie vloeistofstelsel 'n vloeibare orgaan noem?


Bloed word beskou as 'n tipe bindweefsel (soms). 'n Orgaan word egter uit veelvoud gevorm anders weefsels. Dus, bloed is 'n weefsel, nie 'n orgaan nie.


Terwyl organe oor die algemeen beskou word as 'n enkele, gespesifiseerde funksie (of miskien 'n groep nou-verwante funksies), het bloed (die vloeistof binne die vate, nie die vate self nie) baie verskillende funksies:

  • lewer $O_2$ vanaf longe na selle
  • verwyder afval $CO_2$ van selle na longe
  • reageer op besering deur te stol
  • dra verskillende tipes voedingstowwe op verskillende maniere (vryswewend, draerproteïen-geassosieer, lipieddeeltjies, ens.)
  • verskaf vervoer vir die immuunstelsel, wat op sigself uiteenlopende funksies het
  • vervoer afvalprodukte na lewer en niere
  • beweeg regulerende molekules deur die liggaam (hormone, chemokiene, sitokiene, teenliggaampies, ens.)
  • reguleer hitte in die liggaam
  • handhaaf $pH$ en $H_2O$ balans
  • en waarskynlik meer waaraan ek nie gedink het nie

Ek dink dus nie dat bloed as 'n orgaan geklassifiseer moet word nie, net vanweë die vele gebruike daarvan. Dit is in plaas daarvan noodsaaklik vir die behoorlike funksionering van bykans al die organe in die liggaam, en dit maak voorsiening vir verbindings tussen hulle.


Tema 2: Hoe werk bloed- en orgaanskenking?

Vir meer as 'n eeu gee dokters bloed van skenkers toe aan ontvangers wat bloed benodig, en vir meer as 50 jaar het moderne mediese tegnieke pasiënte met nie-funksionele organe toegelaat om hul lewens dekades lank deur middel van oorplanting te verleng. In 'n oorplanting word 'n orgaan of weefsel van 'n skenker verwyder (óf 'n lewende persoon, of een wat baie onlangs oorlede is) en chirurgies ingeplant in die liggaam van 'n ontvanger wie se nie-funksionele orgaan of weefsel eers verwyder is. Orgaan- en weefseloorplanting is egter nie altyd suksesvol nie, en byna alle vroeë pogings tot orgaanoorplanting het misluk as gevolg van onverenigbaarheid tussen die skenker se weefsels of organe en ontvanger se immuunstelsel. Die menslike immuunstelsel val vreemde deeltjies in die liggaam aan om mikrobiese infeksie te voorkom, maar kan ook oorgeplante weefsels en organe aanval en verhoed dat hulle in 'n ontvanger’ se liggaam funksioneer. Voordat die rol van die immuunstelsel in orgaanverwerping verstaan ​​is, was weefsel- en orgaanskenking selde suksesvol, en het dit dikwels tot ernstige en soms dodelike immuunreaksies by die orgaanontvanger gelei. Die eerste suksesvolle orgaanoorplanting het plaasgevind in 1954 deur dr. Joseph Murray in Boston, Massachusetts. Dr Murray het 'n nier van 'n gesonde jong man verwyder en dit oorgeplant in sy identiese tweelingbroer, wat toe langer as 8 jaar oorleef het. Dr. Murray het 'n Nobelprys gewen vir sy werk oor die rol van die immuunstelsel in orgaanoorplanting en -verwerping.

In hierdie afdeling van die kursus fokus ons op die wetenskaplike en etiese kwessies rondom orgaan- en weefseloorplanting. Eerstens leer ons oor bloed en die kardiovaskulêre en respiratoriese stelsels. Dan leer ons meer oor die immuunstelsel, die liggaam se verdediging teen mikrobiese indringers en hoe ons begrip van die funksie daarvan deurslaggewend is vir suksesvolle orgaan- en weefseloorplanting. In lesings en laboratoriums ondersoek ons ​​die prosesse waardeur die genetiese inligting in menslike DNA deur selle gedekodeer word om werklike fisiese verskille in selle te produseer, in transkripsie- en translasieprosesse. Ons ontdek dan die meganismes om DNA van ons ouers te erf en dit aan ons kinders oor te dra, en hoe hierdie oorerwingspatrone ons fisiese eienskappe beïnvloed. Daarbenewens sal ons kwessies aanspreek wat verband hou met etiese ontwerp van navorsingstudies waarby mense en diere betrokke is, ten einde voor te berei vir sommige van die laboratoriumwerk wat in die volgende deel van die kursus opduik.


Hoe reguleer die menslike liggaam sy bloedglukosevlakke?

Sodra 'n persoon 'n maaltyd geëet het, breek sy spysverteringstelsel die voedingstowwe af in kleiner komponente wat in die bloed kan beweeg na enige liggaamsdeel wat dit nodig het. Enige koolhidrate in hierdie kos sal in suikers afgebreek word (bv. glukose). Hierdie suikers sal vinnig die bloed binnedring.

Op hierdie stadium is dit van kritieke belang dat die liggaam die glukose so gou as moontlik kan gebruik hiperglukemie (hoë bloedglukose) en handhaaf 'n konstante bloedglukosevlak. Die glukose in die bloed word dus in gestoor lewer en spier selle in die vorm van 'n groter molekule genoem glikogeen.

Die liggaam is in staat om bloedglukosevlakke op te spoor via 'n orgaan genaamd die pankreas. Meer spesifiek, dit word opgespoor deur gebiede binne die pankreas genoem eilandjies van Langerhans. In hierdie streek is daar 2 tipes selle. Beta-selle en alfa-selle.

Betaselle sal hoë bloedglukose opspoor (bv. Na ete) en afskei insulien. Insulien is 'n hormoon wat die lewer en spierselle sal help om meer glukose op te neem en dit na glikogeen om te skakel, wat die algehele bloedsuikervlakke verlaag.

Alfa-selle sal lae bloedglukose opspoor (bv. Na oefening) en afskei glukagon. Glukagon is ook 'n hormoon, maar dit het die rol om glikogeen af ​​te breek en glukose uit die lewer en spierselle vry te stel. Dit sal die bloedglukose verhoog.

Om 'n oorsig te gee, kommunikeer die komponente in hierdie stelsel met mekaar via hormone om 'n relatiewe resultaat te bied konstant bloedglukosevlak. Hierdie instandhouding van die interne omgewing is 'n voorbeeld van homeostase.


Bloedklonte

Bloedstolling, of stolling, is 'n belangrike proses wat oormatige bloeding voorkom wanneer 'n bloedvat beseer word. Bloedplaatjies ('n tipe bloed sel) en proteïene in u plasma (die vloeibare deel van die bloed) werk saam om die bloeding te stop deur 'n stolsel oor die besering te vorm. Gewoonlik sal u liggaam die bloedklont natuurlik oplos nadat die besering genees is. Soms vorm klonte egter aan die binnekant van vate sonder 'n ooglopende besering of los nie natuurlik op nie. Hierdie situasies kan gevaarlik wees en vereis akkurate diagnose en toepaslike behandeling.

Stollings kan voorkom in are of are, wat vate is wat deel uitmaak van die bloedsomloopstelsel van die liggaam. Alhoewel beide tipes vate help om bloed deur die liggaam te vervoer, funksioneer hulle elkeen anders. Vene is laedrukvate wat gedeoksigeneerde bloed weg van die liggaam se organe en terug na die hart vervoer. 'N Abnormale stolsel wat in 'n aar vorm, kan die terugkeer van bloed na die hart beperk en kan pyn en swelling veroorsaak namate die bloed agter die stolsel ophoop. Diepe veneuse trombose (DVT) is 'n tipe bloedklont wat in 'n groot aar van die been of, minder algemeen, in die arms, bekken of ander groot are in die liggaam vorm. In sommige gevalle kan 'n klont in 'n aar van sy oorsprong losmaak en deur die hart na die longe beweeg waar dit vasgeklem raak, wat voldoende bloedvloei voorkom. Dit word pulmonale (long) embolisme (PE) genoem en kan uiters gevaarlik wees.

Daar word beraam dat DVT elke jaar tot 900 000 1 mense in die Verenigde State raak en tot 100 000 mense doodmaak. 2 Ten spyte van die voorkoms van hierdie toestand, is die publiek grootliks onbewus van die risikofaktore en simptome van DVT/PE. Verstaan ​​jy jou risiko? Kyk na ASH se vyf algemene mites oor DVT.

Hoe DVT tot pulmonale embolisme kan lei

Aartappels, aan die ander kant, is gespierde hoëdrukvate wat suurstof- en voedingsryke bloed uit die hart na ander dele van die liggaam vervoer. Wanneer jou dokter jou bloeddruk meet, is die toetsuitslae 'n aanduiding van die druk in jou are. Stolling wat in arteries voorkom, word gewoonlik geassosieer met aterosklerose (verharding van die are), 'n neerslag van plaak wat die binnekant van die vaartuig vernou. Namate die arteriële gang vernou, gaan die sterk arteriële spiere voort om bloed deur die opening te dwing, en die hoë druk kan die plaak laat skeur. Molekules wat in die breuk vrygestel word, veroorsaak dat die liggaam oorreageer en 'n onnodige stolsel in die slagaar vorm, wat moontlik tot 'n hartaanval of beroerte kan lei. Wanneer die bloedtoevoer na die hart of brein heeltemal deur die klont geblokkeer word, kan 'n deel van hierdie organe beskadig word as gevolg van bloed en sy voedingstowwe ontneem word.

Bloedklonte: 'n Pasiënt se reis

Is ek in gevaar?

Die risikofaktore vir die ontwikkeling van 'n veneuse bloedklont verskil van dié vir 'n arteriële stol, en mense wat die risiko loop om een ​​te kry, loop nie noodwendig die risiko om die ander te kry nie. Verskillende risikofaktore of gebeurtenisse kan onnatuurlike stolling veroorsaak, maar elke faktor kan op 'n ander manier stolling begin. Daar is molekules in jou stelsel wat jou liggaam sein om dit te laat weet wanneer, waar en hoe vinnig om 'n klont te vorm, en genetika speel 'n rol in hoe vinnig jou liggaam op hierdie seine reageer. Sekere risikofaktore, soos vetsug, vertraag die vloei van bloed in die are, terwyl ander, soos ouderdom, die liggaam se natuurlike vermoë om te stol, kan verhoog. Selfs sekere medikasie kan beïnvloed hoe vinnig jou bloed stol.

Die volgende faktore verhoog jou risiko om 'n bloedklont te ontwikkel:

  • Vetsug
  • Onbeweeglikheid (insluitend langdurige onaktiwiteit, lang reise per vliegtuig of motor)
  • Rook
  • Orale voorbehoedmiddels
  • Sekere kankers
  • Trauma
  • Sekere operasies
  • Ouderdom (verhoogde risiko vir mense ouer as 60)
  • 'n Familiegeskiedenis van bloedklonte
  • Chroniese inflammatoriese siektes
  • Suikersiekte
  • Hoë bloeddruk
  • Hoë cholesterol
  • Vooraf sentrale lynplasing

Wat is die simptome van 'n bloedklont?

Behalwe dat u u risikofaktore ken, is dit ook belangrik om bewus te wees van die simptome van bloedklonte, wat wissel na gelang van waar die stolsel geleë is:

  • Hart - swaarkry of pyn op die bors, ongemak in ander dele van die bolyf, kortasem, sweet, naarheid, lighoofdigheid
  • Brein - swakheid van die gesig, arms of bene, probleme met praat, sigprobleme, skielike en erge hoofpyn, duiseligheid
  • Arm of been - skielike of geleidelike pyn, swelling, sagtheid en warmte
  • Long - skerp borspyn, rasende hart, kortasem, sweet, koors, bloedhoes
  • Buik - erge abdominale pyn, braking, diarree

Hoe word bloedklonte behandel?

Bloedklonte word verskillend behandel afhangende van die ligging van die klont en jou gesondheid. As jy simptome ervaar en vermoed jy kan 'n bloedklont hê, gaan dadelik na 'n dokter.

Daar was baie navorsingsvooruitgang wat die voorkoming en behandeling van bloedklonte verbeter het. Sommige huidige behandelings sluit in:

  • Antistolmiddels - medisyne wat voorkom dat klonte vorm
  • Trombolitika - medisyne wat bloedklonte oplos
  • Katetergerigte trombolise-'n prosedure waarin 'n lang buis, wat 'n kateter genoem word, chirurgies ingevoeg word en na die bloedklont gestuur word waar dit geneesmiddels wat ontbind word, verskaf.
  • Trombektomie - chirurgiese verwydering van 'n klont

As u met 'n veneuse stolsel gediagnoseer word, kan u dokter u verwys na 'n hematoloog, 'n dokter wat spesialiseer in die behandeling van bloedsiektes. Mense wat met arteriële siektes gediagnoseer word en 'n risiko loop om 'n stolsel in hul are te ontwikkel, kan verskeie dokters by hul sorg insluit, insluitend 'n kardioloog ('n dokter wat spesialiseer in harttoestande), 'n neuroloog en moontlik 'n hematoloog.

Vir sommige pasiënte bied deelname aan 'n kliniese proef toegang tot nuwe terapieë. As jy gediagnoseer word, kan jy met jou dokter praat oor of om by 'n kliniese proef aan te sluit reg is vir jou.

Is bloedklonte voorkombaar?

Bloedklonte is een van die mees voorkombare tipes bloedtoestande. Daar is verskeie maniere om jou kanse te verminder om 'n bloedklont te ontwikkel, soos om jou risikofaktore te beheer wanneer moontlik. As jy dink jy kan in gevaar wees as gevolg van genetiese of gedragsfaktore, praat met jou dokter. Maak ook seker dat u dokter bewus is van al die medisyne wat u neem en van enige familiegeskiedenis van bloedstollingsversteurings.

Trombotiese trombositopeniese Purpura: 'n pasiënt se reis

Waar kan ek meer inligting kry?

As jy vind dat jy belangstel om meer te wete te kom oor bloedsiektes en -afwykings, hier is 'n paar ander hulpbronne wat dalk van hulp kan wees:

Resultate van kliniese studies Gepubliseer in Bloed

Soek Bloed, die amptelike tydskrif van ASH, vir die resultate van die nuutste bloednavorsing. Terwyl onlangse artikels oor die algemeen 'n intekenaaraanmelding vereis, is pasiënte wat belangstel om 'n toegangsbeheerde artikel te bekyk in Bloed kan 'n afskrif verkry deur 'n versoek per e-pos aan die Bloed Uitgewerskantoor.

Pasiëntgroepe

'N Lys met webskakels na pasiëntgroepe en ander organisasies wat inligting verskaf.

Verwysings

Verwante inhoud

Diepe veneuse trombose (DVT) raak jaarliks ​​duisende mense in die Verenigde State, maar ten spyte van die voorkoms van hierdie toestand, is die publiek grootliks nie bewus van die risikofaktore en simptome van DVT/PE nie. Verstaan ​​jy jou risiko? Kyk na ASH & rsquos vyf algemene mites oor DVT.


Orgaanspesifieke handtekeningprofiele vir bloedvatselle

Navorsers van die Universiteit van Illinois in Chicago het ontdek dat endoteelselle - dié wat die binneste voering van bloedvate skep - unieke genetiese handtekeninge het, gebaseer op hul ligging in die liggaam.

Hul studie, wat in die joernaal gepubliseer word eLife, het 'n genetiese muismodel gebruik om endoteelselle in hul natuurlike orgaanomgewing te vergelyk. Die navorsers het eers na gesonde muise gekyk en vergelyk hoe gene in endoteelselle van hart-, long- en breinweefsel uitgedruk word. Daarna het hulle die endotheelselle van die bloedvat van ongesonde muise bestudeer - dié wat blootgestel is aan 'n bakteriese gifstof, wat ontsteking in die hele liggaam naboots.

Onder beide toestande het endoteelselle van verskillende organe verskillende genetiese handtekeninge uitgedruk.

"Een van die mees verrassende bevindinge van hierdie studie is dat bloedvat-endoteelselle in die brein gene uitdruk wat voorheen gedink is om hoofsaaklik in neurone gevind te word - soos die gene wat betrokke is by die vervoer van neurotransmitters en sinaptiese vesikels," het dr. Jalees Rehman, UIC -professor in medisyne, farmakologie en bioingenieurswese aan die College of Medicine.

Soortgelyke resultate is gevind vir hart-endoteelselle, wat die gene uitgedruk het wat bekend is dat dit hartspierselle help om bloed te klop en te pomp.

"Ons het al 'n geruime tyd anekdotiese beskrywings dat bloedvatselle verskillend in elke orgaan funksioneer, maar nuwer genetiese instrumente het ons toegelaat om 'n globale ontleding van duisende gene in die bloedvate van hierdie lewensbelangrike organe uit te voer," het Rehman gesê.

Rehman het gesê die resultate van hierdie studie kan gebruik word om die bio-ingenieurswese van bloedvate wat spesifiek vir verskillende organe is, in te lig en dat die bevindinge daarop dui dat daar onontginde weë is om meer doelgerigte behandelings te ontwikkel.

'Ons bevindinge bied' poskodes 'vir orgaanspesifieke bloedvate vir die moontlike aflewering van medisyne aan spesifieke weefsels,' het Rehman gesê. "Op die oomblik is die meeste behandelings vir vaskulêre siektes gerig op alle bloedvate, ongeag waar hulle is. Stel jou voor of ons meer effektiewe behandelings kan ontwikkel om die funksie van bloedvate in die hart of die brein uniek te verbeter?"

Rehman het gesê dat hierdie navorsing daarop dui dat bloedvate voorheen onherkenbare rolle kan speel in sommige neurologiese siektes soos Alzheimer se siekte en ander vorme van demensie omdat die brein se endoteelselle gene uitgedruk het wat betrokke is by kognitiewe funksie.


Kardiopulmonêre resussitasie

Bufferoplossings

Hartstilstand lei tot melksuurversaking deur onvoldoende orgaanbloedvloei en swak oksigenasie. Asidose onderdruk miokardiale funksie, verminder sistemiese vaskulêre weerstand en belemmer defibrillasie. Tog word die gereelde gebruik van natriumbikarbonaat vir 'n kind by hartstilstand nie aanbeveel nie. 3 Retrospektiewe kliniese reekse het geen voordelige effek van natriumbikarbonaat getoon nie. 99 Die teenwoordigheid van asidose kan egter die werking van katesjolamiene onderdruk, so die gebruik van natriumbikarbonaat lyk rasioneel in 'n suurdarmige kind wat weerstandbiedend is vir katekolamientoediening. Die toediening van natriumbikarbonaat word duideliker aangedui by die pasiënt met 'n trisikliese antidepressante oordosis, hiperkalemie, hipermagnesemie of natriumkanaalblokkervergiftiging. 3

Die bufferwerking van bikarbonaat vind plaas wanneer 'n waterstofkation en 'n bikarbonaat -anioon saamkom om koolstofdioksied en water te vorm. As koolstofdioksied nie effektief deur ventilasie verwyder word nie, sal die opbou daarvan die buffereffek van bikarbonaat teenwerk. Ander newe -effekte van natriumbikarbonaat sluit in hipernatremie, hiperosmolariteit en metaboliese alkalose. 3,99 THAM is 'n nie-koolstofdioksied-opwekkende buffer wat gebruik kan word tydens hartstilstand. Let daarop dat oormatige alkalose kalsium- en kaliumkonsentrasie verlaag en die oksihemoglobien-dissosiasiekurwe na links verskuif.

'n Belangrike praktiese saak tydens hartstilstand is fisies-chemiese medikasie onverenigbaarheid. Dikwels het die pasiënt slegs een veneuse toegangsplek. Toediening van bikarbonaat kan katekolamiene inaktiveer, en nog belangriker, kalsium presipiteer wanneer dit met bikarbonaat gemeng word. Daarom moet binneaarse buise versigtig besproei word voor en na infusies van natriumbikarbonaat.


Bloedsomloopstelsel van visse

Die stelsel waardeur bloed in verskillende organe en dele van die liggaam sirkuleer, word die bloedsomloopstelsel genoem. Die teenwoordigheid van 'n goed ontwikkelde bloedsomloopstelsel kan met bykans uitsonderings byna alle diere waargeneem word. Vis het 'n geslote tipe bloedsomloopstelsel. Voedsel, suurstof en afvalprodukte word van een deel van die liggaam na 'n ander vervoer deur die bloed wat in so 'n sirkulasiestelsel vloei.

Die bloedsomloopstelsel is aktief betrokke by die beheer van die metabolisme van voedsel, die koördinering van die verskillende organe en stelsels van die liggaam, die bewaring, herstel en vernietiging van verskeie patogene. Alhoewel die bloedsomloopstelsel spesiale eienskappe het in vergelyking met ander organe, is die struktuur daarvan ewe algemeen. Die bloedsomloopstelsel van visse bestaan ​​uit bloed, bloedvate (are en are) en die hart.

Deurlaatbare membrane bestaan ​​in die meeste dele van die visliggaam. Vir hierdie doel word water deur die kieue uitgeruil, en benewens die gasse wat in die kieue opgelos word, word die uitwisseling van sommige stikstofhoudende afvalstowwe en minerale uitgevoer. Die ingang en terugkeer van bloed vanaf die liggaam van die vis na die kieue, behalwe vir die longvis, word deur 'n enkele sirkulasie bewerkstellig. In hierdie geval ruil die hart bloed met lae konsentrasie suurstof en hoë konsentrasie koolstofdioksied.

Die bloedvolume van hoër benige visse (teleost) wissel van 1,5% tot 3% van die totale liggaamsgewig. By soogdiere is die hoeveelheid bloed egter 6% of meer van die liggaamsgewig. Stekelrige hondvis (Squalus acanthias) het 'n bloedvolume van 5% van liggaamsgewig. Plasma of bloedselle van visse word in groter hoeveelhede in verskillende organe of stelsels geproduseer as by soogdiere.

'n Opvallende kenmerk van die bloedsomloopstelsel van visse is dat daar 'n aansienlike aantal kapillêre of sinusvormige stelsels in die arteriële of veneuse bloedvloei is. Die spesiale stelsel wat as gevolg van so 'n kapillêre rangskikking geskep word, word portaalstelsel genoem. Sulke stelsels kom voor in die kieue, lewer (lewerportaalstelsel) en niere (nierportaalstelsel). Daar is ook 'n ander kapillêre wat lyk soos vate in die rete mirabile in een deel van die swemblaas van Physoclystous visse. Die rangskikking van die chloriedkliere in die oë van die teleost is soortgelyk.

Sommige vinnig bewegende visse soos makrielhaaie (Lamnidae), tuna, makriel (Scombridae) het ander organe, soos spesiale kapillêre bloedvat in spiere. As gevolg van hierdie stelsel word die uitruil van gas tussen bloed en weefsels doeltreffender gedoen.

Bloed

Die bloed van visse is dieselfde bindweefsel as ander gewerwelde diere. Die vloeibare deel word plasma genoem en die vaste deel word bloedselle en ander stowwe in die vloeibare deel genoem. Dit bevat die volgende bloedselle: rooibloedselle (eritrosiete of RBC's), witbloedselle (leukosiete of WBC's) en plaatjie (trombosiete). Rooibloedselle is rooi van kleur omdat hulle 'n tipe rooi pigment genaamd hemoglobien dra. Dit speel 'n belangrike rol in die vervoer van suurstof in die bloed.

Nie alle visse het rooibloedselle en hemoglobien nie. Sommige Antarktiese visse (Chaenichthyidae, ysvis ​​of wit krokodilvisse) het kleurlose bloed omdat hulle nie eritrosiete het nie. Die bloed van die klein paling (Leptocephalus larwes) is ook kleurloos. Bloedpigment van Lamprey (Petromyzon) is nie soos die hemoglobien van ander werweldiere nie.

Plasma

Die helder vloeistof wat verkry word deur bloedselle van bloed te skei word plasma genoem. In die wydste sin, as bloed in 'n bottel met antikoagulante versamel word, sal die bloed nie stol nie, en in hierdie geval, as die bloed gesentrifugeer word, sal die bloedselle geskei word en as sediment gestoor word, dan word die oorblywende vloeistof plasma genoem .

As die bloed sonder 'n antistollingsmiddel in 'n bottel versamel word, sal die bloed stol, en in hierdie geval, as dit gesentrifugeer word, word die vloeibare deel serum genoem. In werklikheid verloor serum die bloedstollingskomponent, protrombien en fibrinogeen genoem, maar plasma dra die proteïenagtige bloedstollingskomponent.

Plasma bevat verskeie proteïenkomponente (fibrinogeen, globulien, albumien, ens.), opgeloste minerale (Na + , K + , Ca ++ , Mg ++ , Cl - , HCO3 - , PO4 --- , SO4 -- ), geabsorbeerde komponent as gevolg van vertering (glukose, vetsure, aminosure), weefselafvalprodukte (ureum, uriensuur, kreatien, kreatinien, ammoniumsoute), spesiale afskeidings (hormone en ensieme), teenliggaampies en opgeloste gasse (suurstof, koolstofstikstof). Die sedimentasie-ko-doeltreffendheid van die belangrikste plasmaproteïene wissel van spesie tot spesie.

Die elektroliet (ioon) per liter bloed in kabeljouvis (Gadus callarius) is 180 ml natrium (Na +), 4,9 ml kalium (K +), 3,8 ml magnesium (Mg ++), 5,0 ml kalsium (Ca ++), 5,3 ml chloried (Cl -), 3,1 ml fosfaat (PO4 --- ). Konsentrasies van natrium en chloried is oor die algemeen laer in varswatertelost.

Haaie (Squaliformes) het 'n hoë konsentrasie Mg ++ in hul bloed. Sy bloed is egter effens alkalies as die bloed van hoër beenvisse (Actinopterygii). Die opgeloste materiaal in oplossing dui die vriespunt aan wat ook deur osmotiese druk gemeet kan word. Namate die osmotiese druk van die bloed toeneem, versprei water van die deurlaatbare membraan na die oplossing met 'n lae digtheid.

By varswater benige vis is die vriespunt van plasma 0,5 0 C. Vir sommige varswaterhaaie en ander visse (elasmobranks) is dit 1,0 0 C. Vir mariene benige visse is die waarde 0,6-1,0 0 C. Die maksimum waarde in mariene elasmobranch is 2,17 0 C. Die vriespunt van seewater is 2,08 0 C.

Visse het laer plasmaproteïene as hoër gewerwelde diere. Die belangrikste plasmaproteïene in visse is albumien (wat osmotiese druk reguleer), lipoproteïen (lipiede vervoer), globulien (bind aan hemi-deel), ceruloplasmin (bindend aan koper), fibrinogeen (help met bloedklonte) en iodi-uroforien (slegs gevind in vis, voeg anorganiese jodium by).

Die konsentrasie van plasmaproteïen in vis is 2-6 g / liter. Die teenwoordigheid van lae vlakke van fibrinogeen en protrombienagtige proteïene word nie met vinnige bloedstolling geassosieer nie. Reenboog forel (Salmo gairdneri) kan bo 0 0 C oorleef. By lae temperature stol die bloed van hierdie vis. Omdat serum van Antarktiese visse glikoproteïene bevat, kan hulle by -1,9 0 C oorleef. Die verhouding van albumien en treonien in hierdie proteïen is 2: 1. Die molekulêre gewig daarvan is 2600-33000.

Skildklierbindende proteïene soos T3 en T4 word in die bloedplasma van visse aangetref. By cyprinid -spesies voeg dit vitalogenien by. Dit bevat ook 'n verskeidenheid ensieme soos CPK, alkaliese fosfatase (Alk Pase), SGOT, SGPT, LDH, lipase en koolstofanhidrase en hul ko-ensieme.

As die serum van sommige teleoste, veral Anguilla'n paar baber (Siluridae) en die tuna (Thunnis) druk in die bloed van soogdiere dan wys dit vergiftigingsreaksie.

Tipes bloedliggaampies

Die tipes bloedselle word in die volgende diagram genoem:

1. Rooibloedliggaampies/erytrosiete

Die meeste visse het rooibloedselle met ronde of reghoekige kerne wat in die middel van die sel geleë is en geelrooi van kleur is. Die getalle wissel afhangende van die spesie, ouderdom, seisoen en omgewingsinvloede. Die grootte is groot in Elasmobranch en klein in teleost. In riviermond spesies soos Fundulus, dit is kleiner in grootte as varswater spesies.

Rooibloedselle van diepsee-teloste is groter as gewone teleoste. In spesies soos Clarias batrachus, Notopterus notopterus, Colisa fasciatus, Tor tor, ens., sy struktuur is gewoonlik rond maar in Labeo rohita en Labeo calbasu dit is ovaal van vorm.

Sommige spesies Antarktiese visse wat in suurstofryke gebiede by lae en koel temperature woon, het nie rooibloedselle nie. Daarbenewens het leptocephaluslarwes van palingvisse (Anguilla) en sommige diepseevisse het nie rooibloedselle nie. Hul gaswisseling vind plaas deur diffusie. Die rooibloedselle van die vis is ovaal, klein en 6 mikron in deursnee, maar in baie visse, veral Wrassus (Crenilabrus), die rooibloedselle is meer as 8 mikron in deursnee. In Protopterus, dit is 36 mikron in deursnee.

Die aantal rooibloedselle per kubieke mm bloed in visse is 20,000-3,000,000. Onaktiewe visse het 'n laer aantal rooibloedselle as aktiewe visse.

2. Witbloedkorpuskel

Daar is aansienlike navorsing gedoen oor die witbloedselle van visse, so daar is geen verskil in hul klassifikasie nie. Die aantal per kubieke mm in die bloed van visse is 20,000-150,000. Dit kan granulosiet of agranulosiet wees, maar die aantal granulosiete is hoër. Granulosiete kan verder verdeel word in eosinofiele, basofiele en neutrofiele op grond van hul kleurvermoë.

Neutrofiele en eosinofiele het fagositiese eienskappe. Agranulêre witbloedselle is limfosiete en monosiete. Monosiete produseer teenliggaampies. Basofiele granulosiete kom by sommige spesies voor, maar daar is geen funksie daarvan aangemeld nie.

A. Agranulosiete

(a) Limfosiete: Verskillende tipes limfosiete word in die bloed van visse aangetref. Hul kerne is rond of ovaal van vorm. Limfosiete is 80-90% van die totale witbloedselle. Dit bevat baie chromatien. Soos soogdiere, het vars- en soutwatervis ook groot en klein limfosiete. Groot selle bevat groot hoeveelhede sitoplasma. Hulle het nie korrels in hul sitoplasma nie. Die hooffunksie van limfosiete is om immuniteit te verhoog deur teenliggaampies te maak.

(b) Monosiete: Monosiete is verantwoordelik vir klein hoeveelhede witbloedselle. Sommige visse het egter nie monosiete nie. Daar word vermoed dat hulle uit die niere kom en is sigbaar wanneer 'n ongewenste voorwerp die bloedstroom binnedring. Sy sitoplasma is ligblou of pers van kleur. Die kern is basies groot en het 'n verskeidenheid strukture. Die hooffunksie daarvan is om patogene in die proses van fagositose te vernietig.

B. Granulosiete

(a) Nutrofiel: Die meeste van die witbloedselle in visse is neutrofiele. Neutrofiele is 5-9% van die totale witbloedselle Solvelinus fontinalis en 25% in bruinforel. Hulle word benoem op grond van die kleurvermoë van die sitoplasma. Hulle kerne is meerlobbig, maar sommige visse het neutrofiele met tweelobbige kerne.

By marginale bloeduitstortings bevat die sitoplasma pienk, rooi of pers korrels. Hulle kerne lyk soos menslike niere. Neutrofiele reageer positief met peroksidase en Soedan Swart. Neutrofiele is aktiewe fagosiete. Dit beskerm die weefsels teen inflammasie of besering.

(b) Eosinofiele: Eosinofiele is gewoonlik rond en die sitoplasma daarvan is korrelvormig. In suur oplossing toon dit donker pienk oranje of oranje rooi kleur. Hulle kerne is gelob en vertoon donker oranje tot pers van kleur.

3.Trombosiet

Dit word ook bloedplaatjie genoem. Hulle is rond, ovaal of spilvormig. By soogdiere is die bloedplaatjies egter skyfvormig. Visbloed bevat bloedplaatjies wat ongeveer die helfte van die totale leukosiete is.

Haringvisse bevat 72,2% bloedplaatjies rooibloedselle en slegs 0,7% bloedplaatjies in teleost. Hul sitoplasma is korrelvormig, die middel is meer alkalies en die omtrek is dof en homogeen. In 'n alkaliese oplossing toon hul sitoplasma 'n pienk of rooi kleur. Hulle help met bloedstolling.

Oorsprong van bloedkorpuskel

Die proses om bloedselle en bloedplasma te vorm, word hemopoiese genoem. In die vroeë embrionale stadium word bloedselle uit die wand van die bloedvat geproduseer. Rooibloedselle en witbloedselle is afkomstig van limfoïede hemoblaste of hemositoblaste en gaan die bloedstroom binne om volwasse te word.

By visse is milt en limfknope betrokke by die produksie van bloedselle. In chondrichthyes kom rooibloedselle uit die granulopoietiese weefsel, die leidig-organe, die epigonale organe en selde die niere. Die leidig-orgaan bestaan ​​uit wit weefsels en tree op soos 'n beenmurgweefsel. Sulke weefsels word in die slukderm aangetref, maar die belangrikste bron is die milt. In al hierdie visse, as die milt verwyder word, neem die leidig-organe deel aan die produksie van rooibloedselle.

By teleost kom rooibloedselle en granulosiete uit die niere (pronephros) en milt. Hul milt het 'n rooi korteks aan die buitekant en 'n medulla met 'n wit pulp aan die binnekant. Rooibloedselle word geproduseer uit die kortikale gebied van die milt, terwyl limfosiete en sommige granulosiete uit die medullêre gebied geproduseer word.

Die dermspiraalkleppe van chondrichthyes en Dipnoi produseer ook verskillende soorte witbloedselle. By hoër benige visse (Actinopterygii) word rooibloedselle in die milt vernietig. Die tegniek om bloedselle in kakelose visse te vernietig (Agnatha), Basking Shark and Rays is nie bekend nie.

Trombosiete kom van die mesonefriese nier van visse, granulosiete kom van die submukosa, lewer, geslagskliere en mesonefriese niere van die spysverteringskanaal.

By haaie, strale en chimaera (chondrichthyes) word witbloedselle met bindweefsel onder die slymvlies van die slukderm gesien. In steurgarnale (Acipenser), roeivis (Polyodon) en Suid-Amerikaanse longvisse, produseer die rooibruin lobulêre sponsagtige weefsel rondom die hart limfosiete en granulosiete.

Skedelbene van sommige haaie (Squaliformes), chimaeras (Chimaeridae), Gar (Lepisosteus) en kraniale kraakbeen van Bowfin (Amia) kan alle soorte bloedselle produseer.

Funksie van bloed

Soos ander gewerwelde diere word die gemengde sellulêre komponente van bloedplasma in visse aangetref. Dit bestaan ​​uit 'n tipe van een soort bindweefsel en 'n nie-Newtonse vloeistof. Bloed vloei deur die liggaam deur die kardiovaskulêre stelsel. Dit word hoofsaaklik veroorsaak deur sametrekking van die hartspier. Bloed het verskillende funksies. Die funksies van bloed word hieronder gegee:

1. Asemhaling: Bloed speel 'n belangrike rol in die vervoer van opgeloste suurstof (DO) van water na die kieue (respiratoriese veranderinge) en koolstofdioksied (CO)2) van die weefsels na die kieue.

2. Voeding: Die bloed dra verskeie voedingstowwe soos glukose, aminosure, vetsure, vitamiene en elektroliete, en sekondêre elemente vanaf die spysverteringskanaal na die weefsels.

3. Uitskeiding: Die afvalprodukte wat deur bloedmetabolisme vervaardig word, soos ureum, uriensuur, kreatien, ensovoorts, word uit die selle weggevoer. Alle visse het trimetielamienoksied in hul bloed, maar die konsentrasie daarvan is die hoogste in mariene elasmobranch.

Kreatien is 'n tipe aminosuur wat geproduseer word deur die metabolisme van glisien, arginien, metionien. Die hoeveelheid kreatien in die bloedplasma is 10-60 gram en dit word deur die niere uitgeskei.

4. Homeostase van water- en elektrolietkonsentrasie: Die uitruil van elektroliete en ander molekules vind deur die bloed plaas. The level of glucose in the blood of fish is considered to be a sensitive physiological indicator in most cases and there is no discrepancy in the level of glucose in the blood of fish.

5. Hormones: There are different types of controlling agents in the blood such as hormones and cellular or humoral agents (antibodies). All these elements are present in different concentrations in the blood which are regulated by the feedback loop and change the concentration and make the necessary components of different organs through the synthesis of hormones and enzymes.

Heart: Structure and Functions

The heart is a special pump device with a valve in the circulatory system. In case of fish, the heart is a folded tube that contains three or four enlarged areas. The blood brought through the veins travels from the heart to the gills through the ventral aorta and the heart always contains carbon dioxide (CO2) or unrefined blood. This is why the heart of a fish is called the venous or branchial heart.

Blood passes through the aortic arch on the front and enters the gills to exchange gaseous components through the heart. In most fish, the heart is located immediately after the gills. In the case of the teleost, the heart is located at the front side of the body rather than at Elasmobranch. The heart is primitive type in Elasmobranch among the fish. It is located in the pericardial cavity and consists of the sinus venosus, atrium, ventricle and well-developed contractile conus.

Some researchers consider the atrium and ventricles to be the chambers of the heart. Some researchers also consider the sinus venosus and conus arteriosus to be the chambers of the heart. In the case of fish, there is some controversy over Conus arteriosus and Bulbus aorta. The fourth chamber of the elasmobranch is known as the conus arteriosus. In Teleost, however, it is known as Bulbus arteriosus.

The difference between conus arteriosus and bulbus arteriosus is that conus arteriosus has ventricular like heart-muscle and innumerable valves are continuously arranged in it, but bulbus arteriosus consists only of smooth muscle fibers and elastic tissue. (Boas 1980 Smith 1918 Danforth 1912 Parson 1929 Karandikar and Thakur 1954).

According to Torrey (1971), a teleostian fish (Cyprinus carpio) has both conus and bulbus arteriosus. According to Kumar (1974) and Santer (1977), the teleost has only bulbus arteriosus. On the other hand, Elasmobranch and Agnatha have conus arteriosus instead of bulbus arteriosus.

The heart has sino-auricular and sino-ventricular openings that are controlled by a dual valves. The conus has six rows of valves. Muscular and contractile conus are considered to be of primitive nature. It is found in some lower teleosts such as Acipenser, Polypterus en Lepidosteus.

In addition to conus, bulbus arteriosus exists in the Amia. It originates from the fibrous wall of an uncontrollable region. This type of secondary condition is seen in some lower teleost (Clupeiformes). Albula, Tarpon en Megalops have distinct conus and rows of transverse valves. The size and weight of the heart varies with the body weight of the fish. The structure of the heart of different fish is described below:

Heart of Cyclostomes

Lamprey's (Petromyzon) heart is like the English letter 'S'. It is formed by folding the posterior side of the gill and the sub-intestinal vessels. The larval heart develops as a straight duct. Later, this duct becomes longer and takes the shape of ‍‘S’ in a limited space. The heart consists of the sinus venosus, an atrium and a ventricle, and the conus arteriosus and is covered by the pericardium. A cartilage plate holds the pericardium. The sinus venosus is a thin-walled chamber that is exposed through a sinus-auricular opening to a thin-walled atrium at the top. The atrium is again connected to the thick-walled ventricle through the auricle-ventricular opening.

Heart of Cartilaginous (shark) Fishes

Their heart is a curved muscular duct that consists of the receiving region and the transmitting region. The receiving region consists of a sinus venosus and dorsally located an atrium while anterior portion contains a ventricle and a conus arteriosus. The heart is covered by a membrane called the pericardium. The dorsal part of the pericardium is made up of basibranchial cartilage. The heart is located between the two rows of gill pouches on the ventral side of the body of the fish.

Heart of Bony Fishes

(a) Heart of Tor tor

The heart is located at the tip of the septum transversum in the pericardium sac. It consists of sinus venosus, atrium, ventricle and bulbus arteriosus. The sinus venus is a smooth-walled chamber that receives blood supply through the joint Ductus cuvieri, the joint hepatic vein, a posterior cardinal, and an inferior jugular vein. The openings of these blood vessels have no valves. The sinus venosus is exposed to the atrium through the sinus-auricular opening. In this opening, a pair of membranous semilunar valves are present. Each valve has a long wing pointed towards the front of the atrium.

Heart of Tor tor A. Internal structure of heart B. Cross section of heart

The atrium encloses the ventricle dorsally and is relatively large in size with an irregular outer surface. It is orange and sponge-like soft and has a narrow cavity extending to the ventricles. The spongy wall of the atrium has numerous spaces or cavities covered by muscle fibers extending in different directions. The atrium-ventricular opening contains two pairs of semilunar valves of approximately equal shape. Each valve has a short wing adjacent to the atrium wall and a long wing adjacent to the ventricular wall, but the extended part of the valves points towards the atrium.

The ventricle is a superior muscular chamber with a thick wall and a narrow cavity. It is associated with bulbus arteriosus through ventricular-bulbar opening. There are a pair of semilunar valves in this opening. Each valve has a short wing adjacent to the ventricular wall and a long wing adjacent to the wall of the bulb so that the wings cross each other. The valves are hanging in the ventricular cavity. The wall of the bulbus is thin and has a narrow hole in it. In its cavity, a thin ribbon-like innumerable trabeculae pass parallelly. The bulbus extend into the ventral aorta anteriorly.

(b) Heart of Other Teleosts

The heart of cyprinids such as Labeo rohita, Cirrhina mrigala, Catla catla en Schizothorax has the same general structure as Tor tor. Lebeo rohita, Cirrhina mrigala, en Catla catla have large sinuses and a pair of lateral appendages (Singh 1960). In the first two species, it is spongy and fibrous.

In Clarias batrachus, Mystus aor, Wallago attu, the sinus venosus is a thin-walled chamber in which a pair of membranous sinus-auricular valves are located obliquely along the long axis of the heart. One end of the dorsal valve extends to the front and reaches the atrium cavity and is attached to it.

Heart of A. Wallago attu B. Catla catla

The atrium is structurally spongy type, looking like a beehive. The opening of the atrium ventricle has four valves, two of which are well-developed, while the other two are small, not so important. The ventricle has advanced muscular and two ventriculo-bulbar valves which are semilunar-like in shape. In die geval van Channa striatus, sinus venosus is small and there is no sinus-auricular valve.

Heart of Clarias batrachus

Notopterus notopterus has 5-7 nodular valves in the sinus-auricular opening and Chitala chitala has 8-10 valves. Two of the 4 auricular-ventricular valves are small in size. Chitala chitala has a muscular conus arteriosus between the ventricles and the bulbus. In die geval van Notopterus, the ventricular bulbar valve is like a ribbon with a strange structure and divides the bulbous cavity into three chambers by a pair of vertical septum.

Working of the Heart

The venous blood travels to the heart, reaches the sinuses applying pressure to the semilunar valve, and reaches the atrium. During this time, the pockets of the valves are filled with blood and the pressure created by the contraction of the atria causes the valves to swell ‍ and obstruct the flow of blood from each other.

Due to the pressure of the four auricular-ventricular valves, the blood reaches the ventricle from the atrium and as soon as possible the ventricular cavity is filled with blood. During this time, the valves receive blood. So the valves swell and close the openings from being firmly attached to each other. As a result, the reverse flow of blood is obstructed. The blood then enters the bulbus by applying pressure to the ventriculo-bulbar valve. Inside the bulbus, the blood pressure rises again, causing the valves to swell and close the passageway, obstructing the retrograde flow of blood, causing the blood to flow forward through the ventral aorta.

Cardio-vuscular Control

Fish control the cardio-vascular system in two ways, viz

Aneural cardio-vascular control is accomplished through the direct response of the heart muscle to changes in temperature and the secretion of various glands and changes in blood volume. Temperature acts as an anural regulator due to the direct action of the myocardium on the pacemaker. In some species, an increase in temperature increases the heart rate, resulting in higher cardiac energy. By increasing blood flow, it is able to supply more oxygen to the body. As a result, higher metabolic rate is possible in warm water. Anural control also occurs under the influence of certain hormones such as epinephrine stimulates heart rate.

Neural control techniques occur through the tenth carotid nerve (vegus). The heart of these fish is nerved by a branch of the vegus nerve. Stimulation of the vegus nerve reduces the heart rate in the elasmobranch and teleosts. Different types of stimuli such as flashing light, sudden movement of an object, touch or mechanical vibration reduce the heart rate in fishes. In responding to environmental or other changes, fish face some problems during maintaining their blood circulation balance.

Arterial System of Lamprey

From the ventricle, a large ventral aorta emerges and moves forward through the gill pouches. The base of the ventral aorta is slightly swollen. Some researchers have named this swollen part as the bulbous arteriosus. Eight afferent branchial arteries from the ventral aorta enter into the gill pouches. The afferent branchial arteries divide into capillaries in the gills. Blood is collected from the gills by eight efferent branchial arteries.

Each of the afferent and efferent branchial arteries supplies blood to the posterior hemibranch of a gill pouch and the anterior hemibranch of the next. Each efferent branchial artery carry oxygenated blood from the gill pouch to the paired dorsal aortae. This paired dorsal aortae run backwards and joins to form a single median dorsal aorta. From this dorsal aorta, segmental arteries arise which enters into the myotomes. The segmental artery contains scattered chromafin cells that represent scattered adrenal medulla. Its secretion is similar to that of mammalian adrenalin.

Special arteries are produced from the unpaired dorsal aorta and supply blood to the intestines, kidneys and gonads. With the exception of the efferent branchial and renal arteries, most other arteries have valves at their origin. These valves play an important role in lowering blood pressure in most arteries. Blood flows forward through the ventral aorta and backwards through the paired and unpaired dorsal aortae.

Venous System of Lamprey

Their venous system consists of a complex network of true veins and sinus venouses. Blood is transported from the caudal region through a large caudal vein. This vein divides into two posterior cardinal veins just at the entrance into the abdominal cavity. Cardinal veins collect blood from the kidneys, gonads, and myotomes and ultimately opens to the heart by a single ductus cuvieri on the right side.

The left ductus caviary does not remain in adulthood. Although their presence can be noticed in the larval stage. Blood enters to the heart from the anterior region of the body through a pair of anterior cardinal veins. In addition to these anterior cardinal veins, a large median inferior jugular vein carries blood from the musculature of the buccal funnel and gill pouches. There are no renal portal veins in the lamprey. However, a hepatic portal vein collects blood from the intestine and enters into the liver through a contractile portal heart. A very simple type of portal system exists in the lamprey that connects the hypothalamus with the pituitary.

Blood from the liver enters into the heart through hepatic veins. In addition to the veins, special network of the venous sinus exists, especially in the head region. The branchial sinus is a very important sinus and consists of three longitudinal channels, namely:

(1) The ventral branchial sinus or the ventral jugular sinus

(2) Inferior branchial sinus which is located below the gill pouches

(3) Superior branchial sinus which is located above the gill pouches

All these branchial sinuses are interconnected to each other by gill bars.

Arterial System of Cartilaginous Fish (Scoliodon)

The circulatory system of cartilaginous fish such as Scoliodon is composed of blood, heart, arterial system and the venous system. In Scoliodon, there are two distinct arteries in the arterial system, namely-

The arterial system of Scoliodon is briefly described below:

1. Afferent Branchial Arteries of Scoliodon

Afferent Branchial Arteries begin from the ventral aorta and carries oxygen-free blood to the gills for oxygenation. The ventral aorta is situated on the ventral surface of the pharynx. It extends up to the posterior boundary or hyoid arch. The ventral aorta is divided into two branches called the innominate arteries, each of which re-divides into two branches to form the 1st and 2nd afferent branchial arteries. The 3 rd , 4 th and 5 th afferent branchial arteries originate from the ventral aorta.

Each afferent artery originates from a ventral aorta through an independent opening except for the 1st and 2nd afferent branchial arteries which are exposed to the same common opening.

2. Efferent Branchial Arteries of Scoliodon

Efferent Branchial Arteries arise from the gills and carries oxygenated blood to different parts of the body. The efferent branchial artery divides into capillary blood vessels in the gills. Blood is collected from the gills by efferent branchial arteries.

In Scoliodon, there are 9 pairs of efferent bronchial arteries that are evenly distributed on each side. The first 8 arteries form a series of four complete loops around the first four gill slits.

The 9th efferent branchial artery collects blood from the hemibranch of the 5th gill pouch and from where the blood is poured into the 4th loop. In addition, the shorter longitudinal connector connects the four loops. These are re-connected with each other by a network of longitudinal commissural blood vessels called the lateral hypobranchial chain.

An epibranchial artery originates from each efferent branchial loop. The four pairs of epibranchial arteries join along the mid-dorsal line to form the dorsal aorta. The 9th efferent branchial artery has no epibranchial branch. However, it joins with the 8th efferent branchial artery.

Anterior Arteries

The head region receives blood supply from the 1st efferent branchial artery and partly from the proximal end of the dorsal aorta. The following arteries originate from the 1st efferent branchial artery (hyoidian efferent), viz.

(c) hyoidean epibranchial which gets blood from a branch of dorsal aorta.

The external artery receives blood from the first collecting loop and subsequently divides to produce a ventral mandibular artery and a superficial hyoid artery.

The ventral mandibular artery produces branches to the muscles of the lower jaw and the superficial hyoid artery which supplies blood to the 2nd ventral contractile muscle, the skin and subcutaneous tissue below the hyoid arch.

The afferent spiracular artery originates from the medial space of the hyoidian efferent artery and enters the cranial cavity as it progresses forward as the spiracular epibranchial artery. Just before its entry to the cranial cavity it sends large ophthalmic arteries to the eye ball.

As the spiracular epibranchial artery enters the cranial cavity, it connects to a branch of the internal carotid to form the cerebral artery. It later divides to form an anterior and a posterior cerebral arteries, which supply blood to the brain.

The hyoidian epibranchial artery runs forward and enters the posterior boundary of the eyeball, and it acquires an anterior branch from the dorsal aorta. It later splits to produce (1) the stapedial artery, which re-divides to form the inferior orbital artery and the superior orbital artery. The superior orbital artery moves forward and enters the superficial tissue above the 6 eye muscles and the auditory capsule.

From the superior orbital artery a large buccal artery arises and progresses as the maxillo-nasal artery. A few branches originate from the maxillo-nasal artery and enter the muscles of the upper jaw, the olfactory sac and the rostrum. (2) The internal carotid artery passes inwards and enters the cranium where divides into two branches. One of the branch unites with its fellow from the opposite side and the other branch unites with the stapedial.

Dorsal Aorta and its Branches

The epibranchial arteries converge to form the dorsal aorta and move posteriorly. It is situated on the ventral side of the vertebral column. It extends up to the tip of the tail as a caudal artery. The dorsal aorta along the antero-posterior direction produces the following arteries, viz.

(1) Several buccal and vertebral arteries- which originate from anteriorly

(2) Subclavian arteries-originate from the fourth epibranchial artery. An epicoracoid artery originates from the subclavian artery. The subclavian artery subsequently re-divides into three branches, namely-

(i) the branchial artery which enters the pectoral girdle and pectoral fins

(ii) an antero-lateral artery which enters the body musculature

(iii) a dorso-lateral artery which enters the dorsal musculature

(3) A large coeliaco-mesenteric artery-arises from some posterior part of the origin of the 4th epibranchial artery. It is further divided into two parts, such as a smaller coeliac artery and a larger anterior mesenteric artery

(4) Lienogastric artery-it originates from the posterior part of the ciliaco-mesenteric artery and divides into the following branches, viz.,

(I) an ovarian (in female) or spermatic artery (in male) that enters the genital organs

(ii) a posterior intestinal artery- which enters the posterior part of the intestine

(iii) a posterior gastric artery-which enters the posterior part of the cardiac stomach

(iv) a splenic artery-which enters the spleen

(5) Paired parietal arteries - which originate from the posterior part of the subclavian artery. Each parietal artery is divided into a dorsal and a ventral parietal artery.

The dorsal parietal artery supplies blood to the dorso-lateral musculature, the vertebral column, spinal cord, and the dorsal fin. The arterial parietal artery supplies blood to the ventral muscles and the peritoneum. From this paired parietal artery, the renal artery enters the kidney.

(6) A pair of iliac arteries-that extend to the pelvic fin and become known as the femoral arteries.

Hypobranchial Chain

A network of slender arteries arising from the loop of the ventral ends of the efferent branchial artery forms a lateral hypobranchial chain. From it, four commissural blood vessels are formed and join the ventral wall of the ventral aorta to form a pair of median hypobranchials which are connected to each other by transverse blood vessels.

Posteriorly, the median hypobranchials unite to forms a median coracoid artery from which the coronary artery and a pericardial artery originate. The common epicoracoid artery originates from the pericardial artery and later divides into the right and left epicoracid arteries, each of which is connected to a subclavian artery.

Venous system of Cartilaginous Fish (Scoliodon)

Deoxygenated blood from different parts of the body returns to the heart through veins. The structure of veins differ from the arteries which possess thin walls and frequently valves. The valves help to prevent backward flow of blood. Throughout the passages of blood, several veins form wide irregular blood sinuses without definite walls. The presence of extensive blood sinuses is a special feature of the venous system of Scoliodon. Their venous system is very complex. The venous system of Scoliodon can be divided into the following headings:

1.Cardinal system

(i)Anterior cardinal system,

(ii) Posterior cardinal system,

2.Hepatic portal system, and

1. Cardinal System

Blood returns to the heart from the anterior part of the body through the paired jugular and anterior cardinal sinuses. Blood from the posterior region is received through a pair of posterior cardinal sinuses. The anterior and posterior cardinal sinuses on each side combine to form a transverse sinus called the ductus cuvieri. The cardinal system can be divided into two parts, namely :

(1) Anterior cardinal system and

(2) Posterior cardinal system.

(1) Anterior Cardinal System

Blood from the head region (brain) returns to the heart through the veins of this system. It consists of a pair of internal jugular veins. Each internal jugular vein consists of the olfactory sinus, orbital sinus, post-orbital sinus, and anterior cardinal sinus.

Blood is transmitted through the anterior facial vein from the rostral region and enters the olfactory sinus. From there it goes to the orbital sinus. The orbital sinus is exposed to the anterior cardinal sinus through the post-orbital sinus. The anterior cardinal sinus enters the ductus cuvieri. The anterior cardinal sinus receives the hyoidian sinus and the 5 dorsal nutrient branchial sinus from the gills.

(2) Posterior Cardinal System

The caudal vein collects blood from the tail region and moves forward through the haemal canal. In the abdominal cavity, the caudal vein divides to form the right and left renal-portal vein, which divides into a sinusoid capillaries in the kidney. Along its entire length, the renal-portal vein acquires small parietal veins. Renal veins receive blood from the kidneys and then unite to form the posterior cardinal sinus. The two posterior cardinal sinuses open in the ductus cuvieri.

2. Hepatic Portal System

A significant number of small veins collect blood from the alimentary canal and its associated glands and later merge to form the hepatic portal vein. Lienogastric vein, anterior and posterior gastric veins merge with the hepatic portal vein.

In fact, the anterior and posterior gastric veins combine to form the hepatic portal vein. It is divided into capillaries in the liver. Blood is collected from the liver through another set of capillaries which later merged to form two large hepatic sinuses that are exposed to the sinus venosus.

3. Cutaneous System

Cutaneous system consists of a dorsal, a ventral and two pairs of lateral cutaneous veins. The inferior lateral cutaneous vein is connected to the lateral cutaneous vein near the anterior edge of the thoracic/pectoral fin. Each lateral cutaneous vein is usually combined with the branchial vein.

4. Ventral System

Ventral system consists of two sets of veins, namely :

(1) anterior ventral vein- which carries blood to the ductus cuvieri through the inferior jugular sinuses and

(2) posterior cardinal vein- it supplies blood through the subclavian vein.

The veins of each inferior jugular are composed of the submental sinuses of the lower jaw, the hyoidean sinus and the ventral nutrient sinuses from the gills. The jugular veins of each inferior are exposed in the ductus cuvieri. The subclavian vein is also exposed in the ductus cuvieri on each side.

Two large lateral abdominal veins are formed with a small caudal vein and two iliac veins. The lateral abdominal vein is connected to the posterior part by a commissural vein. Anteriorly, the lateral abdominal veins merge with the branchial veins to form the subclavian vein which is exposed to the ductus cuvieri.

Arterial System of Teleosts

The ventral aorta moves forward and gives off four pairs of afferent branchial blood vessels of which third and fourth pairs originate from the same common location of the ventral aorta and supply blood to the third and fourth gills. These blood vessels travel to the holobranchs on each side and reach to the paired blood capilaries of the gill lamellae. In gills, blood is oxygenated and blood is collected through four pairs of efferent branchial arteries.

Blood circulation layout of bony fish

Each gill arch contains one efferent blood vessel, the first two of these originate dorsally from the gills and connects to form the first epibranchial blood vessel. The epibranchial arteries on both sides runs the posteriorly and join to form the dorsal aorta. The third and fourth efferent branchial blood vessels originate from the corresponding holobranch and join to form a short second epibranchial blood vessel which opens into the dorsal aorta.

A short common carotid artery originates from the first efferent branchial blood vessel, protrudes and divides somewhat to form an external carotid and an internal carotid artery. The carotid artery near its base receives blood from an efferent pseudobranchial artery coming from the pseudobranch. A cerebral artery is generated from the common carotid artery and supplies blood to the brain. The external carotid artery divides into numerous branches and supplies blood to the operculum, auditory region, and muscles of the jaw.

The internal carotid artery supplies blood to the snout and optic region. A small branch is formed from the internal carotid artery and goes along the midline towards the front and joins with the branch coming from the other side to form the circulas cephalicus. The dorsal aorta extends posteriorly below the vertebral column. The subclavian artery arises from the dorsal aorta just behind the second epibranchial artery and supplies blood to the pectoral fins.

The coeliaco-mesenteric artery arises from the dorsal aorta just behind the subclavian artery and progresses a little further, splitting into two branches called the coeliac and mesenteric arteries. The coeliac artery supplies blood to the anterior region of the intestine. On the other hand, mesenteric artery gives off branch and supplies blood to the liver, spleen, gonads, and to the rest of the alimentary canal.

The dorsal aorta reaches through the kidney and produces a few pairs of renal arteries on its lateral side. One of these pairs reaches into the two pelvic fins, and then the dorsal aorta continues posteriorly, becoming known as the caudal artery along the middle of the hemal canal, and gives off a few pairs of segmental arteries that expand into the muscle during its course.

The above description represents an ideal arrangement of arterial system in teleost. However, some variations in the arteries can be observed in different species of freshwater, such as the four pairs of afferent branchial arteries arise in the Catla catla that originate independently. Maar in Mystus aor, Rita rita, Tor tor, Clarias batrachus, Heteropneustes fossilis, Wallago attu, Chitala chitala, the third and fourth arteries on each side originate from the same common place. In a very small number of species of fish, such as Rita rita en Heteropneustes fossilis, the second pair of afferent arteries originate in the same common way from the ventral aorta.

In some species, such as the Catla catla, Tor tor have a pseudobranch which arise from first efferent branchial artery and receives blood supply through the afferent pseudobranchial artery. Blood is collected through the afferent pseudobranchial artery that connects to the internal carotid artery. Mystus aor does not have a pseudobranch. In this case, the base of the internal carotid artery is swollen to form a labyrinth.

The alimentary canal and its associated glands receive blood supply from the branches of the coeliaco-mesenteric artery. The gonads receive blood from the coeliaco-mesenteric or the posterior mesenteric arteries.

Venous System of Teleost

Blood is collected from the head through the external and internal jugular veins which combine on each side to form the anterior vein. The internal jugular veins receive blood supply from the premaxillary, nasal, and eye regions. External jugular veins, on the other hand, collect blood from the maxillary and mandibular regions.

The anterior cardinal vein receives blood from the opercular and subclavian veins before opens into the ductus cuvieri. A single inferior jugular vein collects blood from the ventral surface of the pharynx and is exposed to the sinus venosus.

There is a single posterior cardinal vein in the teleost that reaches to the right kidney. The renal veins coming from both kidneys are exposed to the posterior cardinal vein and runs forward and is exposed into the sinus venosus.

The blood coming from the tail is collected through the caudal veins which gain some segmental veins and are exposed to the kidneys. Hepatic portal veins collect blood from different regions of the alimentary canal, spleen, swimbladder, and gonads and reach to the liver. Later, two hepatic veins are generated from the liver and supply blood to the sinus venous.

In Tor tor, this venous system represents the ideal venous system of teleost. However, some variations in the venous system can be observed in different species of freshwater fish. The inferior jugular veins are usually unpaired. But in some fish, such as Clarias batrachus, have two inferior jugular veins. In Tor tor, Catla catla, Wallago attu, the posterior cardinal veins are unpaired. Maar in Clarias batrachus it is paired. Although the right posterior cardinal vein is more developed in this species.

Lymphatic System of Teleost Fishes

Like other vertebrates, fish collect lymph from all parts of the body through a system consisting of paired and unpaired ducts and sinuses, which ultimately return into the main bloodstream. The upper vertebrates have lymph nodes but are absent in fish.

The lymphatic system of lamprey and hagfish (Cyclostomata) is characterized by more numerous and more diffuse connection with the blood circulatory system than exists in other groups of fishes. Because of this close connection, the blood vessels are called the hemolymph system. The lamprey and hagfish have a large abdominal lymph sinus that enters into the lymphatic ducts of the kidneys and gonads.

There are several valve openings in the sinuses of the cardinal vein. The valves allow lymph flow to enter the veins and prevent a back flow of venous blood into lymph sinuses. The headcervical region of lamprey contains superficial and deep lymph sinuses where the valves of a lymphatic peribranchial sinus are connected to the jugular veins.

In the Elasmobranch, the lymphatic system contains much lymph vessels than the sinuses, but the cyclostomata and osteichthyes do not contain contractile lymph ‘heart’.

The sub-vertebral lymph trunk is situated in the hemal canal of the tail vertebrae which collects lymph fluids from the tail region. It then merge into the abdominal lymph duct which form a network of blood vessels with the lymphatic system.

The lymph-collecting vessels from the segmental musculature and intestinal organs flows into the sub-intestinal lymph trunk which in turn open into the cardinal sinuses near the site of origin of the subclavian artery from the aorta. Subvertebral lymph trunks extend into the head and where they collect lymph from the cranial and branchial regions.

The lymphatic system of fish is thought to be more likely to originate from the veins than the arterial part of the blood circulatory system. In Elasmobranchii, Chondrostei and Holostei, the complexity of its growth, development and number is gradually increased.

In teleostei, the arrangement of the lymphatic vessels is better than that of the terrestrial vertebrate, and the branches of the subcutaneous lymphatic ducts are more extensive. The lymph from the head region collects in the branched sinuses and flows into the sub-scapular sinuses of the pectoral region, where it is unite by fluid from the three main lymphatic ducts of the body-the dorsal, lateral, and vertebral subcutaneous lymph trunks.

Neural, arterial, and hemal sub-musculature lymph trunk collect the lymph fluids from body musculature. On the other hand, the lymphatic ducts of the visceral organs divide and form superficial and a deep systems. The deep visceral lymphatic duct absorbs fat from the intestinal mucosa and carries it to the ciliaco-mesenteric lymph trunk where the remaining lymphatic ducts are probably connected to the subvertebral trunk.

The lymph enters into the paired para-renal lymphatic duct from the bladder, gallbladder, abdominal part of the kidney, and other organs of the body cavities and subsequently ends in the pericardial sinus.

In Actinopterygii, the lymph reaches the main bloodstream through the anterior (cephalic) lymph sinus, which opens into the cardinal vein, and such conditions can be observed in conger eel(Comger) and freshwater eel (Anguilla).

The opening of the anterior lymph sinus connecting the blood and lymphatic system, also exists in the jugular vein, as seen in some fish Morays (Muraena), and in Pike (Esox), or in the posterior cardinal veins as in some members of the family Salmonidae (Salmo).

In conger eel (Conger) and freshwater eel (Anguilla), a false lymph heart is located in the cephalic sinus and keeps the lymph flow intact through the movement of the gills but a true lymph heart with valves and cardiac muscle contractile fibers occurs in the caudal region of both Anguilla en Salmo.

A small blister-like flattened structure appears in the hypural on the ventral of the last vertebra of the true lymph heart, which is covered by muscles and skin. They make contact with the lymphatic ducts and caudal veins of the body and are double-chambered and valved they are thought to further venous flow.

Fish Blood as a Gas Carrier

Oxygen spreads from one liquid to another very slowly. Red blood cells have appeared in fish and other vertebrates to achieve high efficiency in gas transport. This is why one volume of blood can carry 15-25 times more oxygen than water. 99% red blood cells and 1% plasma contribute to this oxygen transport. The red blood cells of fish and other vertebrates contain a type of pigment called hemoglobin. In its presence, the blood turns red and acquires the ability to transport oxygen. In most vertebrates, the molecular weight of a hemoglobin is about 65,000. The oxygen carrying capacity of hemoglobin of some fish is given in the table below:


16.2 Review Questions

Why Can We Regrow A Liver (But Not A Limb)? MITK12Videos, 2015.

Are Sports Drinks Good For You? | Fit or Fiction, POPSUGAR Fitness, 2014.

Why do we sweat? – John Murnan, TED-Ed, 2018.


For most people, 80 to 99 milligrams of sugar per deciliter before a meal and 80 to 140 mg/dl after a meal is normal. The American Diabetes Association says that most nonpregnant adults with diabetes should have 80 to 130 mg/dl before a meal and less than 180 mg/dl at 1 to 2 hours after beginning the meal.

These variations in blood-sugar levels, both before and after meals, reflect the way that the body absorbs and stores glucose. After you eat, your body breaks down the carbohydrates in food into smaller parts, including glucose, which the small intestine can absorb.


Digestive System

The digestive system serves mainly to break down consumed food into nutrients for the body to absorb. The main organs implicated in the digestive system are the esophagus, stomach, small intestine, and large intestine. The process of digestion actually starts as soon as you put food into your mouth. The combination of chewing and saliva breaks down the food enough to be swallowed down the esophagus. Rhythmic contractions of the esophageal lining (known as “peristalsis”) transport food into the stomach, where it is exposed to numerous digestive acids. Mucus produces by stomach cells protect the inside of the stomach from gastric acids strong enough to dissolve stainless steel blades.

Once food has been processed in the stomach, it moves through the duodenum to the small intestines. While in the small intestine, the majority of nutrient absorption occurs. Tiny finger-like filaments on the inside of the intestinal wall called villi draw nutrients out of the digested food and the continued peristalsis pushes food further down the GI tract. Next, the digested material enters the large intestine where any water is absorbed and the remaining material is stored as feces which is later expelled through the rectum. The digestive system is the single longest organ system in the body as the small intestine alone is between 6-7 meters long slightly longer than three average adult humans.

“Digestion is one of the most delicately balanced of all human and perhaps angelic functions.” — M. F. K. Fisher

There are a number of other organ systems found in humans such as the skeletal system meant for providing internal structure, the musculature system for locomotion and manipulation of the environment, the nervous system meant to let the brain communicate with the rest of the body, the endocrine system which sends messenger hormones to the body telling it how to behave, the reproductive system, and the integumentary system composed of skin, hair, fat, and nails.

In actuality, most organ systems do not have clearly defined boundaries and they all operate interdependently. The lymph system is extremely closely related to the circulatory system, and the activity of the respiratory system feeds directly into the circulatory system. None of the organ systems would work if the digestive system could not get energy from nutrients in food, and the digestive system would not be able to function if the nervous system could not send electrical signals from the brain to the intestines. So, the various organ systems of the human body form a complex interconnected network and cannot operate in isolation from each other. It is only when they are integrated into a complete biological organism do the organs systems perform their main functions


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