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ENDOCRINE SYSTEM
DEPARTMENT PHYSIOLOGY
UNIVERSITY OF SUMATERA UTARA
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OBEJECTIVE
• Explanation o Ho!"on#$ C%a!a&t#!i$ti&
an' F(n)tion
• Explanation o Ho!"on# !#pto!$
• Explanation o !#)(lation %o!"on#
$#&!#tion
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Comparison of Nervous and
Endocrine Systems
NOTE* N#!+o($ an' #n'o&!in# $,$t#"$ -o!. to)#t%#! to
&oo!'inat# an'
int#)!at# a&ti+iti#$ o /o', 0%o"#o$ta$i$1
N#!+o($ En'o&!in#
messenger #l#&t!o&%#"i&al
%o!"on#0&%#"i&al1
!#$pon$# "illi$#&on'$ $#&on'$ to 'a,$
'(!ation $%o!t2li+#' lon)2li+#'
'i$t!i/(tion on# $,$t#" 0$#+#!al
$(/$,$t#"$1
-i'#l, $&att#!#'
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Ho!"on#$ C%a!a&t#!i$ti& an' F(n&tion
The endocrine system is one of the body’s
two major communication systems, the
nervous system being the other.The endocrine system consists of
all those
glands, termed endocrine glands, that
secrete hormones.
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ormones• &%#"i&al$
• $#&!#t#' /, #n'o&!in# )lan' ll$ into /loo'0/, -a,
o int#!$titial l(i'1
• !#)(lat# "#ta/oli& (n&tion$ o ot%#! ll$
0&all#' ta!)#t ll$1• &a!!i#' to all ll$3 /(t a&tion
i$ $p#&ii& to
ll$ t%at %a+# !#pto!$ o! t%# %o!"on# 4 $p#&ii&it, o
/o',5$ !#$pon$# to %o!"on#
'#p#n'$ on %o- "an, ll$ %a+# t%# !#pto! 0%i)%l,
$p#&ii& i #- ll$ !#$pon' 6#7)73 ACTH89'i($# a&tion i
"an, !#$pon' 6#7)73 t%,!oxin#81
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Chemical Types of ormones• A"ino2a&i'
/a$#' 0a"ino a&i'$3 $%o!t o! lon)
p#pti'#$3 p!ot#in$1 4 #7)73 in$(lin3 )!o-t% %o!"on#3
p!ola&tin
• St#!oi'$ 2 lipi' '#!i+ati+#$ o &%ol#$t#!ol
4 #7)73 %o!"on#$ !o" )ona'$ 0t#$to$t#!on#3#$t!o)#n1
4 #7)73 %o!"on#$ !o" a'!#nal &o!t#x
0a'!#no&o!ti&al
%o!"on#$1
• Ei&o$anoi'$ 2 locally!secreted3 locally!acting%o!"on#$
$#&!#t#' /, all ll "#"/!an#$
0#7)73 p!o$ta)lan'in$3 -%i&% in&!#a$# /loo'
p!#$$(!# an' &ont!i/(t# to (t#!in# &ont!a&tion1
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"unctions of Endocrine System
:7R#p!o'(&tion
;7G!o-t% an' '#+#lop"#nt
7R#)(lation o ll(la! "#ta/oli$" an'#n#!),0ti!oi'3 pa!ati!oi'
%o!"on3 T
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Ho!"on# R#pto!$
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#echanisms of $ction
• a&tion in ta!)#t ll '#p#n'$ on !#pto! • !#pto! "a,
/#*
4 in pla$"a "#"/!an#
• $#&on' "#$$#n)#! "#&%ani$"$• ($#' /, "o$t a"ino
a&i'2/a$#' %o!"on#$ 0water
soluble1
4 int!all(la! 0in &,topla$" o! n(&l#($1
• direct gene a&ti+ation
• ($#' /, $t#!oi'$ an' t%,!oi' %o!"on#$ 0lipid
soluble1
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#echanisms of $ction% Steroids
• /in' to int!all(la! !#pto!$• %o!"on# 'i($#$
t%!o()% pla$"a "#"/!an#
an' "a.#$ it$ -a, to n(&l#($
4 ? -%#!# it /in'$ -it% int!all(la! !#pto! to
o!"
%o!"on#2!#pto! &o"pl#x
4 ? %o!"on#2!#pto! &o"pl#x int#!a&t$ -it%
&%!o"atin 0DNA1 to a#&t )#n# a&ti+it, 0t(!n
)#n#$
on o! o1
4 ? $,nt%#$i$ o "RNA
4 ? $,nt%#$i$ o p!ot#in
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Steroid Signaling
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#echanism of $ction%
Thyroid ormone
• $i"ila! to "#&%ani$" o! steroid %o!"on#$
• diffuses a&!o$$ pla$"a "#"/!an#
4 'i($#$ into n(&l#($ -%#!# it int#!a&t$ -it%
int!all(la! !#pto!$ to a&ti+at# )#n#$ o!
p!ot#in$ 0#n@,"#$1 in+ol+#' in ll(la! !#$pi!ation
0)l,&ol,$i$1
4 al$o3 /in'$ to !#pto!$ at "ito&%on'!ia to
a&ti+at#)#n#$ o! p!ot#in$ in+ol+#' in ll(la! !#$pi!ation
0!#/$ &,&l# an' #l#&t!on t!an$po!t &%ain1
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#embrane 'eceptor #echanisms%
(. Cyclic $#) *c$#)+ Signaling
• int#!a&tion o %o!"on# -it% !#pto! 4 ? a&ti+at#$ G
p!ot#in 0&l#a+#$ p%o$p%at# !o"
GTP12? #x&itation 4 ? G p!ot#in a&ti+at#$
a'#n,lat# &,&la$#
4 ? a'#n,lat# &,&la$# o!"$ & !o"
ATP 4 ? & a&ti+at#$ p!ot#in .ina$#$ 4 ?
p!ot#in .ina$#$ a&ti+at# 0o! in%i/it1 ot%#!
p!ot#in$ /, p%o$p%o!,lation
4 ? & '#)!a'#' /, #n@,"#• $li)%tl, 'i#!#nt G
p!ot#in ina&ti+at#$
a'#n,lat# &,&la$# 2 a$$o&iat#' -it%'i#!#nt %o!"on#
!#pto!
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c$#) Signaling #echanism
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#embrane 'eceptor #echanisms%
. )-)!Calcium Signaling
• int#!a&tion o %o!"on# -it% !#pto! 22?
a&ti+at#$ "#"/!an#2/o(n' #n@,"#
p%o$p%olipa$#
4 ? p%o$p%olipa$# &l#a+#$ PIP; 0p%o$p%ati',l
ino$itol 'ip%o$p%at#1 into 'ia&,l)l,!ol 0DAG1 an'
IP
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)-)!Calcium #echanism *con’t+
2? Ca;C 0t%i!' "#$$#n)#!1
4 &%an)#$ #n@,"# a&ti+it, an' pla$"a
"#"/!an# &%ann#l$3 o!
4 /in'$ to &al"o'(lin 0int!all(la! !#)(lato!,
p!ot#in1 22? a&ti+at#$ #n@,"#$
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)-)!Calcium Signaling #echanism
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"actors $ffecting Target Cell
$ctivation
a7/loo' l#+#l$ o %o!"on#3 -%i&% '#p#n' on*
4 !at# o %o!"on# !#l#a$#
4 !at# o '#a&ti+ation 0/, ta!)#t ll o! li+#!1
/7ainit, o %o!"on# o! !#pto!
4 )!#at#! ainit, "#an$ )!#at#! a$$o&iation 22?
)!#at#! ##&t
&7 n("/#! o !#pto!$ a+aila/l#
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"actors $ffecting Target Cell
$ctivation *con’t+c. number of receptors
available
4 up!regulation% increase in blood level of
specific
hormone *normally present at low levels+ causes cells to
mae more receptors
4down!regulation% prolonged e/posure to high level
ofspecific hormone !!0 cells remove some receptors
!!0return to normal response level
4 cross!regulation% influence of one hormone on
number
of receptors for another hormone1 e.g., progesterone
causes uterus to mae fewer estrogen receptors1
estrogen causes uterus to mae more progesterone
receptors *( reseptor untu hormon berbeda+
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R#)(lation Ho!"on# S#&!#tion
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Control of ormone 'elease
• H("o!al &ont!ol
• N#(!al &ont!ol 4 &t% * .at#.ola"in
• Ho!"onal &ont!ol 4 &t%* %o!"on
* %o!"on ti!oi'3 .o!#t#.$ a'!#nal3 )ona'
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Control of ormone 'elease% umoral
Ho!"on# !#l#a$#' in !#$pon$# to &%an)in) /loo'
l#+#l$ o ion o! n(t!i#nt 0n#)ati+# ##'/a&.1
• parathyroid glands*
'#t#&t$ lo- /loo' Ca;
PTH !ai$#$ /loo'
Ca;
• t%,!oi' 0pa!aolli&(la!
ll$1 '#t#&t %i)% /loo'
Ca;
22?&al&itonin22?'#&!#a$# /loo' Ca;
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Control of ormone 'elease% umoral
Ot%#! #xa"pl#$*
• pan&!#a$*
4 /#ta ll$ '#t#&t %i)% /loo' )l(&o$#
in$(lin
'#&!#a$#$ /loo' )l(&o$#
4 alp%a ll$ '#t#&t lo- /loo' )l(&o$#
)l(&a)on !ai$#$ /loo' )l(&o$#
• @ona )lo"#!(lo$a 0o a'!#nal &o!t#x1
'#t#&t$ lo- /loo' Na o! %i)% /loo'
al'o$t#!on#tt%,3 ↓
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Control of ormone 'elease% Neural Ho!"on# !#l#a$#' in
!#$pon$# to n#!+# i"p(l$#
• p!#)an)lioni&
i/#!$ o
$,"pat%#ti&
'i+i$ion $ti"(lat# !#l#a$#
o &at#&%ola"in#$
0#pin#p%!in#3
no!#pin#p%!in#1!o" a'!#nal
"#'(lla
• i"p(l$#$ !o"
%,pot%ala"($
!#$(lt in !#l#a$# o
o/ytocin or $2!o" po$t#!io!
pit(ita!,
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Control of ormone 'elease% ormonal
Ho!"on# p!o'(' /, on# #n'o&!in# )lan' 0o!%,pot%ala"($1
a#&t$ $#&!#tion o %o!"on# /,
anot%#! #n'o&!in# )lan'
• %,pot%ala"($ a&t$ a$ o+#!all &oo!'inato!
!#l#a$#$ !#)(lato!, %o!"on#$ 0!#l#a$in)%o!"on#$ o! in%i/ito!,
%o!"on#$1 a#&t$
anterior pituitary
• ant#!io! pit(ita!,3 -%#n $ti"(lat#'3 $#&!#t#$
%o!"on#$ t%at a#&t ot%#! )lan'$ 0#7)73 TSH
6t%,!oi' $ti"(latin) %o!"on#8 $ti"(lat#$ !#l#a$# o
t%,!oi' %o!"on#$ !o" t%,!oi' )lan'1
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ormonal Control% 'ole of ypothalamus• 'eleasing hormones from
hypothalamus
stimulate secretion from anterior pituitary• -nhibitory hormones
from hypothalamus
inhibit secretion by anterior pituitary
• -mpulses from hypothalamus cause release
of hormones from posterior pituitary
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ormone Control ! #isc7
• nervous system can override normal endocrinecontrol
4 e.g., in 3fight!or!flight4 response, sympathetic
impulses result in release of epinephrine and
norepinephrine from adrenal medulla !!0 increases
blood glucose levels to maintain fuel supply during
stress or e/ertion *overrules effect of insulin on blood
glucose level+
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