Pancreas as an Endocrine Gland

8/18/2019 Pancreas as an Endocrine Gland

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ROLE OF PANCREAS AS ANROLE OF PANCREAS AS AN

ENDOCRINE GLANDENDOCRINE GLAND


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Functional Anatomy:Functional Anatomy:

Concentration of pancreatic hormones isConcentration of pancreatic hormones ishi her in the li!er than the peripheralhi her in the li!er than the peripheraltissuestissuesRoute of secretion: pancreasRoute of secretion: pancreas pancreaticpancreatic

!ein!ein portal !einportal !ein li!erli!er

DigestiveDigestive EndocrineEndocrineAciniAcini Islets of Lan erhansIslets of Lan erhans

"#"# $rypsin an% $rypsin an%ChymotrypsinChymotrypsin

Car'o(ypolypepti%Car'o(ypolypepti%asease

)#)# ProlactaseProlactase

"#"# Gluca ons *alpha cells+Gluca ons *alpha cells+&,-.&,-.

Insulin */eta cells+ 01-.Insulin */eta cells+ 01-.)#)# Somatostatin *Delta+ "1-.Somatostatin *Delta+ "1-.2#2# Pancreatic polypepti%e *PPPancreatic polypepti%e *PP

cells.cells.


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Secretes 'oth INS3LIN an%Secretes 'oth INS3LIN an%

GL3CAGONGL3CAGON& cell types:& cell types:

"#"# acini 4 secrete %i esti!e 5uicesacini 4 secrete %i esti!e 5uices

islets of Lan erhans :islets of Lan erhans :"#"# alpha *&,-. 4 secrete luca onsalpha *&,-. 4 secrete luca ons 'eta *01-. 4 secrete insulin'eta *01-. 4 secrete insulin)#)# %elta *"1-. 4 secrete somatostatin%elta *"1-. 4 secrete somatostatin

Insulin inhi'its luca ons secretion+Insulin inhi'its luca ons secretion+an% somatostatin inhi'its 'othan% somatostatin inhi'its 'othinsulin an% luca ons secretioninsulin an% luca ons secretion


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INS3LININS3LIN

A protein 6ith a 78 of ,91,+A protein 6ith a 78 of ,91,+composin of & amino aci% chainscomposin of & amino aci% chainsconnecte% to each other 'y %isul %econnecte% to each other 'y %isul %elin;a elin;a e

Synthesis 'e ins 6ithSynthesis 'e ins 6ith translationtranslation ofofthe insulin RNA 'y ri'osomes *rou hthe insulin RNA 'y ri'osomes *rou hER.ER. Insulin Prohormone *78 "",11.Insulin Prohormone *78 "",11.

cleavingcleaving *smooth ER.*smooth ER. ProinsulinProinsulin*78


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INS3LININS3LINSecretion is %irectly relate% to theSecretion is %irectly relate% to thea!aila'ility of ener y> i!in foo%s in thea!aila'ility of ener y> i!in foo%s in the%iet%ietIt stores e(cess car'ohy%rates asIt stores e(cess car'ohy%rates as

lyco en mainly in the li!er an% muscleslyco en mainly in the li!er an% musclesan% some as fats store% in the a%iposean% some as fats store% in the a%iposetissuetissueIt also causes fat stora e in the a%iposeIt also causes fat stora e in the a%iposetissuetissue

It has a %irect e?ect in promotin aminoIt has a %irect e?ect in promotin aminoaci% upta;e 'y cells an% con!ertin themaci% upta;e 'y cells an% con!ertin themin protein an% inhi'it the 'rea;%o6n ofin protein an% inhi'it the 'rea;%o6n ofthe latter in the cellthe latter in the cell


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E?ect of InsulinE?ect of Insulin

/in%s an% acti!ates 6ith the a su'units/in%s an% acti!ates 6ith the a su'unitsof receptor protein at the cellof receptor protein at the cellmem'rane 6hich 6ill in turn acti!atemem'rane 6hich 6ill in turn acti!atethe ' su'units locate% insi%e the cellthe ' su'units locate% insi%e the cell

$he $he @@ su'units 6hich then 'ecome ansu'units 6hich then 'ecome anacti!ate% en yme+ a protein ;inase+ 6illacti!ate% en yme+ a protein ;inase+ 6illin turn acti!ate other intracellularin turn acti!ate other intracellularen ymesen ymes

Lon er e?ects 6oul% occur in hours an%Lon er e?ects 6oul% occur in hours an%%ays %ue to the chan e% rates of%ays %ue to the chan e% rates oftranslation of mRNAs at the ri'osomestranslation of mRNAs at the ri'osomesto form ne6 proteins an%to form ne6 proteins an%


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E?ect of InsulinE?ect of InsulinSlo6er e?ects from chan e% rates ofSlo6er e?ects from chan e% rates oftranscription of DNA in the celltranscription of DNA in the cellnucleusnucleus

$he en% result is that the cells $he en% result is that the cellsmem'rane almost imme%iatelymem'rane almost imme%iately'ecomes permea'le to lucose+'ecomes permea'le to lucose+amino aci%s+ potassium ions an%amino aci%s+ potassium ions an%phosphate ionsphosphate ions8ith the entry of lucose an% other8ith the entry of lucose an% otherions+ other intracellular en ymes 6illions+ other intracellular en ymes 6ill'ecome acti!ate%'ecome acti!ate%


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Glucose 7eta'olism in 7usclesGlucose 7eta'olism in 7uscles3n%er normal con%itions+ muscles use fatty aci%s3n%er normal con%itions+ muscles use fatty aci%sas source of ener yas source of ener yDurin e(ercise+ 'y contraction of the musclesDurin e(ercise+ 'y contraction of the muscles

'ers+ lucose is use% as source of ener y e!en'ers+ lucose is use% as source of ener y e!enat the a'sence or minimal concentration ofat the a'sence or minimal concentration of

insulininsulinImme%iately after a meal+ lucose is ta;en up 'yImme%iately after a meal+ lucose is ta;en up 'ythe muscles initially as source of ener y %ue tothe muscles initially as source of ener y %ue tothe lar e secretion of insulin 'y the pancreasthe lar e secretion of insulin 'y the pancreasE(cess lucose 6ill 'e store% as lyco en in theE(cess lucose 6ill 'e store% as lyco en in themusclemuscle


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Li!er 3pta;e+ Stora e+ an% 3se ofLi!er 3pta;e+ Stora e+ an% 3se ofGlucoseGlucose

After a meal, After a meal,Insulin inacti!ates li!er phosphorylase 6hichInsulin inacti!ates li!er phosphorylase 6hich6ill pre!ent the 'rea;%o6n of lyco en6ill pre!ent the 'rea;%o6n of lyco enInsulin enhances upta;e of lucose 'y theInsulin enhances upta;e of lucose 'y the

li!er cells 'y increasin the acti!ity ofli!er cells 'y increasin the acti!ity ofluco;inaseluco;inaseInsulin increases the acti!ities of theInsulin increases the acti!ities of theen ymes that promote lyco en synthesisen ymes that promote lyco en synthesis

such as lyco en synthase+ 6hich issuch as lyco en synthase+ 6hich isresponsi'le for polymeri ation of theresponsi'le for polymeri ation of themonsacchari%e units to form the lyco enmonsacchari%e units to form the lyco enmoleculesmolecules


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In between meals,In between meals,Decrease% lucose le!els causeDecrease% lucose le!els cause%ecrease% insulin secretion%ecrease% insulin secretion

lyco en stora e processes arelyco en stora e processes are

stoppe%stoppe% phosphorylase isphosphorylase isacti!ate%acti!ate% lyco en is split intolyco en is split intolucose phosphatelucose phosphate lucoselucose

phosphatase 6ill then remo!e thephosphatase 6ill then remo!e the

phosphate from the lucose an% thephosphate from the lucose an% thelatter is then returne% to the 'loo%latter is then returne% to the 'loo%


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Other E?ects of GlucoseOther E?ects of Glucose

E(cess lucose after lyco en is store%E(cess lucose after lyco en is store%6ill 'e con!erte% to fatty aci%s 6hich6ill 'e con!erte% to fatty aci%s 6hichare su'seBuently transforme% toare su'seBuently transforme% totri lyceri%es an% lo6>%ensitytri lyceri%es an% lo6>%ensity

lipoproteinslipoproteins $he tri lyceri%es an% LDL 6ill 'e $he tri lyceri%es an% LDL 6ill 'etransporte% to the a%ipose tissues an%transporte% to the a%ipose tissues an%store% as fatstore% as fat

Gluconeo enesis is inhi'ite% %ue to theGluconeo enesis is inhi'ite% %ue to thee?ects of insulin on the li!er en ymese?ects of insulin on the li!er en ymesan% the %ecrease% release of aminoan% the %ecrease% release of aminoaci%s reBuire% for luconeo enesisaci%s reBuire% for luconeo enesis


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E?ect on Fat 7eta'olismE?ect on Fat 7eta'olismIncreases the utili ation of lucose an%Increases the utili ation of lucose an%

%ecreases the utili ation of fats 4%ecreases the utili ation of fats 4 fat sparerfat sparerPromotes fatty aci% synthesis in the li!er 6hichPromotes fatty aci% synthesis in the li!er 6hichthen 6ill 'e transporte% to an% store% in thethen 6ill 'e transporte% to an% store% in thea%ipose tissuesa%ipose tissues

Glycolysis !ia lycolytic path6ay 6th acetylGlycolysis !ia lycolytic path6ay 6th acetyl

coen yme A+ su'strate for the pro%uction ofcoen yme A+ su'strate for the pro%uction offatty aci%sfatty aci%sCitrate an% Iso>citrate ions from the citricCitrate an% Iso>citrate ions from the citricaci% cycle acti!ates car'o(ylate acetyl>CoAaci% cycle acti!ates car'o(ylate acetyl>CoAto form malonyl>CoAto form malonyl>CoA

$ri lyceri%es+ the stora e form of fatty aci%s+ $ri lyceri%es+ the stora e form of fatty aci%s+are split into fatty aci%s 'y insulin an%are split into fatty aci%s 'y insulin an%a'sor'e% into the a%ipose cells asa'sor'e% into the a%ipose cells astri lyceri%estri lyceri%esInhi'ition of the hormone>sensiti!e lipaseInhi'ition of the hormone>sensiti!e lipase


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Purpose:Purpose: Assist insulin in re ulatin 'loo%Assist insulin in re ulatin 'loo%

lucose *su ar. in the normal ran elucose *su ar. in the normal ran e *actions are *actions are oppositeopposite of insulin)of insulin)Action:Action: Forces many cells of the 'o%y toForces many cells of the 'o%y torelease *or pro%uce. lucose *increasin 'loo%release *or pro%uce. lucose *increasin 'loo%

su ar.su ar.Secreted in response to:Secreted in response to: Lo6 'loo% lucose Lo6 'loo% lucoseSecretion inhibited by:Secretion inhibited by: =i h 'loo% lucose =i h 'loo% lucoseDisease due to de cient action:Disease due to de cient action: SomeSome

times nothin + sometimes hypo lycemiatimes nothin + sometimes hypo lycemiaDisease due to excess action:Disease due to excess action: =yper lycemia=yper lycemiaTumor called:Tumor called: Gluca onoma Gluca onoma

lucagonlucagon

http://www.endocrineweb.com/insulin.htmlhttp://www.endocrineweb.com/insulin.htmlhttp://www.endocrineweb.com/insulin.htmlhttp://www.endocrineweb.com/insulin.htmlhttp://www.endocrineweb.com/insulin.htmlhttp://www.endocrineweb.com/insulin.htmlhttp://www.endocrineweb.com/insulin.htmlhttp://www.endocrineweb.com/insulin.htmlhttp://www.endocrineweb.com/insulin.html


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SomatostatinSomatostatin Purpose:Purpose: Re ulate the pro%uction an%Re ulate the pro%uction an%e(cretion of other en%ocrine tumorse(cretion of other en%ocrine tumorsAction:Action: Slo6s %o6n pro%uction of insulin+Slo6s %o6n pro%uction of insulin+

luca on+ astrin+ an% other en%ocrine tumorsluca on+ astrin+ an% other en%ocrine tumorsSecreted in response to:Secreted in response to: =i h le!els of=i h le!els ofother en%ocrine hormonesother en%ocrine hormonesSecretion inhibited by:Secretion inhibited by: Lo6 le!els of otherLo6 le!els of otheren%ocrine hormonesen%ocrine hormonesDisease due to de cient action:Disease due to de cient action: PoorlyPoorly%e ne%%e ne%Disease due to excess action:Disease due to excess action: Dia'etesDia'etes*inhi'its insulin pro%uction.+ allstones+ an%*inhi'its insulin pro%uction.+ allstones+ an%%ietary fat intolerance#%ietary fat intolerance#Tumor called:Tumor called: SomatostatinomaSomatostatinoma

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Pancreas as an Endocrine Gland