Secretory Function of Gastrointestinal System

7/24/2019 Secretory Function of Gastrointestinal System

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SECRETORY FUNCTION OFGASTROINTESTINAL SYSTEM

Irawan Yusuf

Department of Ph s!o"o#


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INTRODUCTION

Throu#hout the #astro!ntest!na" tra$t se$retor#"an%s ser&e two pr!mar fun$t!on'

To pro%u$e %!#est!&e en( mes' To pro&!%e mu$us for "u)r!$at!on an% prote$t!on Most %!#est!&e se$ret!ons are forme% on" !n

response to the presen$e of foo% !n the

#astro!ntest!na" tra$t The t pes of en( me an% !ts $omponent are

&ar!e% a$$or%!n# to the t pes of foo% present*


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Da!" Se$ret!on of Gastro!ntest!na" F"u!%

F"u!% Da!" &o"ume +m", p-

Sa"!&a ./// 0*/ 1 2*/Gastr!$ se$ret!on .3// .*/ 1 4*3Pan$reat!$ se$ret!on ./// 5*/ 1 5*46!"e ./// 2*5Sma"" !ntest!na" se$ret!on .5// 2*3 1 5*/

6runner7s #"an% se$ret!on 8// 5*/ 1 5*9Lar#e !ntest!na" se$ret!on 8// 2*3 1 5*/

Tota" 02//

Guyton, AC; 2000


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GENERAL PRINCIPLES Fun$t!ons of #astro!ntest!na" se$ret!ons

Transport D!#est!on Prote$t!on

A)sorpt!on The t pe of se$retor #"an%s

Mu$us #"an% or mu$us $e""s +Go)"et $e""s, P!ts' !n&a#!nat!on of surfa$e "!n!n# ep!the"!a" Tu)u"ar #"an%s +stoma$h an% upper %uo%enum, Comp"e: #"an%s +Sa"!&ar #"an%s; pan$reas an% "!&er,

6as!$ me$han!sm of se$ret!on ) #"an%u"ar $e""s Se$ret!on of or#an!$ su)stan$es


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6as!$ Me$han!sm of Se$ret!on

Se$ret!on of Or#an!$ Su)stan$es +prote!ns,.* The nutr!ent mater!a" nee%e% for format!on of se$ret!on must

%!ffuse or a$t!&e" transporte% from the $ap!""ar !nto the)ase of #"an%u"ar $e""

8* ATP from the m!to$hon%r!a; a"on# w!th appropr!atesu)strates; !s then use% for s nthes!s of the or#an!$ su)stan$es

4* The se$retor mater!a"s are then transporte% to the Go"#!$omp"e:

=* In the Go"#! $omp"e: the mater!a" are mo%!f!e% )efore%!s$har#e% !nto the $ top"asm !n the form of se$retor&es!$"es; wh!$h are store% !n the ap!$a" en%s of the se$retor$e""s

3* These &es!$"es rema!n store% unt!" ner&ous or hormona"st!mu"at!on $ause them to e:tru%e the!r $ontents


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6as!$ Me$han!sm of Se$ret!on

Se$ret!on of


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6as!$ Re#u"ator Me$han!smof G"an%u"ar Ce""s

Effe$t of Lo$a" Conta$t The me$han!$a" present of foo% $auses the #"an%s to

se$rete mo%erate to "ar#e ?uant!t!es of %!#est!&e @u!$e

Effe$t of enter!$ ner&ous s stem Ta$t!"e st!mu"at!on

Chem!$a" !rr!tat!on D!stent!on of the #ut wa""

Autonom!$ st!mu"at!on Paras mpathet!$ !n$rease the rate of se$ret!on S mpathet!$ $an ha&e %ua" effe$t' !n$rease or %e$rease

the se$ret!on %epen% on the rate of st!mu"at!on

-ormona"


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-ormones that re#u"ate se$ret!on Gastr!n

St!mu"ates #astr!$ a$!% peps!no#en se$ret!on

Se$ret!n St!mu"ates pan$reat!$ an% )!"e se$ret!on

Cho"e$ stoB!n!n +CC , St!mu"ates pan$reat!$ en( me se$ret!on an% )!"e

se$ret!on


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CELLULAR MEC-ANISMS Se$on% messen#ers

IP4; $a"$!um; $AMP A$t!ons

a"ter a$t!&!t of !on transporters a"ter e:o$ tos!s rate of se$retor &es!$"es re#u"ate !nsert!on of !ntra$e""u"ar

$ana"!$u"!


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SALI ARY GLANDS AND

SALI ASa"!&a !s se$rete% pr!mar!" ) three pa!rs of #"an%s

.* Parot!%; "o$ate% near the an#"e of the @aw; are"ar#est #"an%s an% se$rete a water f"u!%

8* Su)man%!)u"ar; se$rete a f"u!% that $onta!ns ah!#h $on$entrat!on of prote!ns an% so !smo%erate" &!s$ous

4* Su)"!n#ua"; pro%u$e &!s$ous f"u!%


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Chara$ter!st!$s of ea$h of the sa"!&ar #"an%s!n human

Gland Histologic type Secretion 1 % of total saliva 2

Parotid Serous Watery 20Submandibular i!ed oderately "0

viscousSublingual ucous #iscous $

Ganong, WF, 2003. Serous $e""s se$rete pt a"!n'mu$ous $e""s se$rete mu$!n8The rema!n!n# 3 of sa"!&ar &o"ume !s pro%u$e ) "!n#ua" an% m!nor #"an%s In the ora" $a&!t


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Sa"!&a Fun$t!on

Prote$t!on the mouth ) Coo"!n# hot foo% D!"ut!n# #astr!$ a$!% or )!"e re#ur#!tate% !nto the mouth


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Compos!t!on of Sa"!&a

Sa"!&ar #"an% se$rete sa"!&a a)out .>.*3L %a $onta!n!n#

E"e$tro" te* In $ompar!son w!th p"asma; sa"!&a !sh poton!$ an% $onta!ns h!#her $on$entrat!ons of G an% -CO 4 > an% "ower $on$entrat!on of Na G

an% C" >

Prote!ns* Se&era" prote!ns are foun%; >am "ase+pt a"!n,; "!n#ua" "!pase; pero:!%ase; I#A an%#rowth fa$tors +NGF; EGF,

Mu$!n for foo% "u)r!$at!on


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Contro" of Sa"!&ar Se$ret!on

Autonom!$ Ner&ous S stem Paras mpathet!$ $ause se$ret!on of water f"u!%; h!#h

e"e$tro" te )ut "ow !n prote!n In$reases se$ret!on of am "ase w!th "ar#e &o"umes of f"u!%

S mpathet!$ $ause se$ret!on of sma"" &o"ume of f"u!%$onta!n!n# h!#h mu$!n

St!mu"ates sma"" &o"ume of sa"!&a r!$h !n am "ase;

)!$ar)onate an% Sa"!&ar ref"e:es* Thou#ht; aroma; or taste $ause

sa"!&ar ref"e:es


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GASTRIC SECRETION

Gastr!$ a$!% se$ret!ons a!% !n the )reaB%own offoo% !nto sma"" part!$"es

Cont!nue the pro$ess of %!#est!on )e#un )sa"!&ar en( mes

A)out 8 L %a of #astr!$ se$ret!on are pro%u$e%


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Gastr!$ Se$retor Ce""s

Gastr!$ se$retor $e""s are "o$ate% on the surfa$e ofthe stoma$h an% !n #"an%s that are )ur!e% w!th!nthe mu$osa $ons!ts of O: nt!$ #"an%s are "o$ate% !n the fun%us an% $orpus*

The $onta!n three t pes of se$retor $e""s The par!eta" +o: nt!$, $e""s; se$rete -C" an% !ntr!ns!$ fa$tor Pept!$ +$h!ef, $e""s se$rete peps!no#en; the pre$ursor of

peps!n

Mu$ous $e"" se$rete mu$us P "or!$ #"an%s are "o$ate% !n antrum an% p "or!$* The

$onta!n G $e""s an% some mu$ous $e""* G $e""s pro%u$e#astr!n hormone


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Se$ret!on of the Stoma$h

- %ro$h"or!$ A$!% +-C", Peps!no#en Intr!ns!$ Fa$tor Mu$us

G" $oprote!n pro%u$ts wh!$h pr!marfun$t!on as "u)r!$ant; )ut $an a"so ha&e manother re#!ona"" spe$!a"!(e% fun$t!on


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-C" Se$ret!on

Me$han!sm -C" se$ret!on -C" !s se$rete% !nto the par!eta" $e""s $ana"!$u"! ) three

step pro$ess The a$t!&e transport pro$ess !s )e#un ) the transport of an%

C"> !nto the $ana"!$u"! - !s then e:$han#e% for ) a - > ATPase

The a$t!&e transport pro$ess !n&o"&e% !n the #enerat!onof -C"> se$ret!on re?u!re a "ar#e amount of ATP

The p- of a$!% se$ret!on as "ow as /*5


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Contro" of -C" Se$ret!on

St!mu"at!on of -C" se$ret!on A$et "$ho"!ne +A$h,

-!stam!ne' h!stam!ne $an st!mu"ate -C"se$ret!on %!re$t" or $an potent!ate these$ret!on pro%u$e% ) ACh or #astr!n

Gastr!n Inh!)!t!on of -C" se$ret!on

Somatostat!n


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Phases of Gastr!$ Se$ret!on

Cepha"!$ &a#a" $ho"!ner#!$ st!mu"at!on of -C" se$ret!on %!re$t" !n%!re$t" &!a #astr!n

Gastr!$ #astr!n; "o$a" %!stens!on; &a#a" !nput !n$rease #astr!$

a$!% se$ret!on

Intest!na" !n$rease% a$!% !n %uo%enum st!mu"ates se$ret!n

re"ease wh!$h fee%s )a$B to !nh!)!t #astr!n re"ease an%!nh!)!t #astr!$ a$!% se$ret!on


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PEPSINOGEN SECRETION

Fun$t!on of peps!no#en* Peps!n the a$t!&e formof peps!no#en !s proteo" t!$ en( me that )e#!ns

the pro$ess of prote!n %!#est!on Re#u"at!on of peps!no#en se$ret!on*

Cepha"!$ state; &a#a" ner&e st!mu"ate se$ret!on ofpeps!no#en

Gastr!$ phase; "ow p- st!mu"ate se$ret!on Intest!na" phase; se$ret!n st!mu"ate peps!no#en

re"ease


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MUCOSAL 6ARRIER

The #astr!$ mu$osa" )arr!er prote$ts the #astr!$"!n!n# $e""s from %ama#e

The ma!n $omponent of mu$us !s a th!$B&!s$ous a"Ba"!ne mu$ous "a er se$rete% ) themu$ous $e""s

M!"%" !n@ur resu"ts !n !n$rease% mu$us

se$ret!on an% surfa$e %es?uamat!on More ser!ous !n@ur %enu%es the mu$osa"surfa$e; form!n# an u"$er; an% pro%u$e )"ee%!n#


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INTRINSIC FACTOR

Intr!ns!$ fa$tor !s a #" $oprote!n se$rete%) the par!eta" $e""s of the #astr!$ mu$osa;

most" !n fun%us Intr!ns!$ fa$tor !s re?u!re% for the

a)sorpt!on of &!tam!n 6 .8 Intr!ns!$ fa$tor forms a $omp"e: w!th &!tam!n

6.8 The $omp"e: !s $arr!e% to the term!na" !"eum;

where the &!tam!n !s a)sor)e%


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PANCREATIC SECRETION Pan$reas $onta!ns en%o$r!ne an% e:o$r!ne $e""s The e:o$r!ne $e""s ha&e an !nterna" stru$ture s!m!"ar to

that of sa"!&ar #"an%s

The e:o$r!ne $e""s pro%u$e four t pes of %!#est!&een( me Protease +tr ps!n; $h motr ps!n; $ar)o: pept!%ase, Am "ase

L!pases +"!pase; $ho"estero" esterase; phospho"!pase, Nu$"eases

Ea$h %a pan$reas pro%u$e .8//>.3// m" of pan$reat!$

@u!$e $onta!n!n# h!#h $on$entrat!on of -CO 4>


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Anatom an% -!sto"o# of Pan$reas


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Pan$reat!$ Se$retor Ce""s

Pan$reat!$ e:o$r!ne $e""s are arran#e%!n #rape>"!Be $"usters $a""e% a$!n!*

The e:o$r!ne $e""s themse"&es are pa$Be%

w!th mem)rane>)oun% se$retor#ranu"es wh!$h $onta!n %!#est!&een( mes that are e:o$ tose% !nto the"umen of the a$!nus*

From there these se$ret!ons f"ow !nto

"ar#er an% "ar#er; !ntra"o)u"ar %u$ts;wh!$h e&entua"" $oa"es$e !nto the ma!npan$reat!$ %u$t wh!$h %ra!ns %!re$t"!nto the %uo%enum*


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Compos!t!on of Pan$reat!$ Se$ret!on

Pan$reat!$ @u!$e !s $ompose% of two se$retorpro%u$ts $r!t!$a" to proper %!#est!on D!#est!&e en( mes; se$rete% ) a$!nar $e""s

6!$ar)onate +-CO 4>

,; se$rete% from ep!the"!a" $e""s D!#est!&e en( mes %!#est!n# a"" three ma@or

t pes of nutr!ents -CO 4 > p"a !mportant ro"e !n neutra"!(!n# the

a$!% $h me from the stoma$h


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Compos!t!on of -uman Pan$reat!$ Hu!$e

Cat!ons An!ons D!#est!&e En( mes

Na -CO 4> Tr ps!n

C"> Ch motr ps!nsCa 8 SO =8> L!paseM# 8 -PO =8> >am "ase

Car)o: pept!%ase A an% 6

R!)onu$"easeE"astasePhospho"!pase A 8Cho"ester " ester h %ro: "ase


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Contro" of Pan$reat!$ Se$ret!on

-ormona" Contro" Se$ret!n +from !n$rease% -C" !n %uo%enum,

st!mu"ates f"u!% an% e"e$tro" te se$ret!on

CC +from !n$rease% fatt a$!%s; pept!%es;am!no a$!%s, st!mu"ates re"ease of en( mes

Ner&ous S stem

Paras mpathet!$ !nput !n!t!ates se$ret!on %ur!n# $epha"!$ an% #astr!$ phases


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Phase of Pan$reat!$ Se$ret!on

Cepha"!$ phase a#a" st!mu"at!on St!mu"ates en( me se$ret!on

Non>$ho"!ner#!$ -CO 4> se$ret!on

Gastr!$ phase D!stens!on of the antrum an% $orpus

Se$ret!on of "ow &o"ume of en( mes an% -CO 4>

Foo% )reaB%own +pr!mar!" am!no a$!%s, Se$ret!on of pan$reat!$ se$ret!on

Intest!na" phase Cho"e$ stoB!n!n Se$ret!n


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Secretory Function of Gastrointestinal System

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