Human Endocrine
System
gland
, N e r v o us + e n d ocri n e s y ste m s = e n a b le a n i m a ls = r esp o n d to e x te r n a l c h a n g es
= co n trol i n te r n a l b o d y co n d itio n s
Chemical co-ordination:
A slo w /p rolo n g e d p roc ess = co m m u n ic a te i n fo = b o d y = b y c h e m ic a ls = h or m o n es
V a riet y of h or m o n es = se cr ete d = sp e ci a l gl a n ds or tissu e = e n d ocri n e gl a n ds
E n d ocri n e s y ste m w orks w it h n e r v o us s y ste m
Hormone:
O r g a n ic su bst a n c e
Usu a ll y = p rotei n BUT so m e ti m es = ste roid
Se cr ete d b y = a n e n d o cri n e gl a n d
C a rrie d i n b loo dstr e a m to t a r g et org a n /s w h e r e it = r e g u l a tes m et a b olic r e a ctio n s
l a st lo n g a s = b rok e n d o w n b y e n z y m es
Target organ:
A lt h o u g h h or m o n es = c a rrie d i n b loo d = t h ro u g h o u t b o d y = o n l y a ff e ct c e rt a i n c ells
Sp e cific c ells = r e c e p tor sites for sp e cific h or m o n e = sp e cific c ell to r esp o n d = h or m o n e
Sp e cific c ells = t a rg et tissu e or t a rg et org a n s
↳ c a n b e = si n gle gl a n d/ or g a n or sc a tte r e d t h ro u g h o u t b o d y
Endocrine gland:
V a sc u l a r/d u ctless gl a n d
Se cr etes h or m o n es t h a t = c a rrie d i n = b loo dstr e a m = to t a rg et or g a n s
V a sc u l a r = ric h l y su p p lie d w it h b loo d c ells
Exocrine vs. endocrine glands:
E x ocri n e gl a n ds
↳ se cr etio n s = c a rrie d = d u cts = to w h e r e n e e d e d
↳ e g. s a li v a r y gl a n ds/li v e r/p a n cr e a s
E n d ocri n e gl a n ds
↳ d u cts se cr etio n s = c a rrie d = b loo dstr e a m = to t a rg et or g a n s
, Endocrine Glands in the human body:
1. H ypo th a la m u s
HYPOTHALAMUS
P a rt of b r a i n
Loc a tio n = a b o v e p it u it a r y gl a n d
Hor m o n es se cr ete d = A n ti - d i u r etic h or m o n e ( A DH)
= O x y toci n
gland
Anti-diuretic hormone (ADH):
Pro d u c e d = h y p ot h a l a m us
BUT stor e d + r ele a se d fro m p it u it a r y
T a r g et or g a n = colle cti n g d u cts = n e p h ro n i n ki d n e y
F u n ctio n = os m or e g u l a tio n = r e g u l a tes a m t. H2 O = b loo d
= r a ises b loo d p r ess u r e
C o n se r v i n g w a te r
↳ os m or e c e p tors i n h y p ot h a l a m us b loo d v esse ls
↳ d ete ct = i n cr e a se d of os m ol a rit y
↳ lo w H2 O le v els of b loo d
↳ h y p ot h a l a m us = r esp o n ds = r ele a se A DH
↳ if b o d y = d e h y d r a te d =
↳ m or e H2 O = r ele a se d i n to b loo d
↳ fro m colle cti n g d u cts of ki d n e y
↳ less w a te r = lost i n u ri n e
V ic e v e rs a for w h e n = too m u c h w a te r i n b loo d
Oxytocin:
Pro d u c e d = h y p ot h a l a m us
BUT = stor e d + r ele a se d fro m p it u it a r y
T a r g et or g a n = u te r us
= b r e a st tissu e
F u n ctio n = co n trols c h il d b irt h
↳ u te r us co n tr a ctio n
= co n trols l a ct a tio n
↳ m a m m a r y gl a n d co n tr a ctio n
↳ = m ilk ej e ctio n = b r e a st f e e d i n g
= co n trols a sp e cts of h u m a n b e h a v io u r
↳ “c u d d le c h e m ic a l”
↳ e g. m ot h e r - i n f a n t b o n d i n g
se x u a l a ro us a l
System
gland
, N e r v o us + e n d ocri n e s y ste m s = e n a b le a n i m a ls = r esp o n d to e x te r n a l c h a n g es
= co n trol i n te r n a l b o d y co n d itio n s
Chemical co-ordination:
A slo w /p rolo n g e d p roc ess = co m m u n ic a te i n fo = b o d y = b y c h e m ic a ls = h or m o n es
V a riet y of h or m o n es = se cr ete d = sp e ci a l gl a n ds or tissu e = e n d ocri n e gl a n ds
E n d ocri n e s y ste m w orks w it h n e r v o us s y ste m
Hormone:
O r g a n ic su bst a n c e
Usu a ll y = p rotei n BUT so m e ti m es = ste roid
Se cr ete d b y = a n e n d o cri n e gl a n d
C a rrie d i n b loo dstr e a m to t a r g et org a n /s w h e r e it = r e g u l a tes m et a b olic r e a ctio n s
l a st lo n g a s = b rok e n d o w n b y e n z y m es
Target organ:
A lt h o u g h h or m o n es = c a rrie d i n b loo d = t h ro u g h o u t b o d y = o n l y a ff e ct c e rt a i n c ells
Sp e cific c ells = r e c e p tor sites for sp e cific h or m o n e = sp e cific c ell to r esp o n d = h or m o n e
Sp e cific c ells = t a rg et tissu e or t a rg et org a n s
↳ c a n b e = si n gle gl a n d/ or g a n or sc a tte r e d t h ro u g h o u t b o d y
Endocrine gland:
V a sc u l a r/d u ctless gl a n d
Se cr etes h or m o n es t h a t = c a rrie d i n = b loo dstr e a m = to t a rg et or g a n s
V a sc u l a r = ric h l y su p p lie d w it h b loo d c ells
Exocrine vs. endocrine glands:
E x ocri n e gl a n ds
↳ se cr etio n s = c a rrie d = d u cts = to w h e r e n e e d e d
↳ e g. s a li v a r y gl a n ds/li v e r/p a n cr e a s
E n d ocri n e gl a n ds
↳ d u cts se cr etio n s = c a rrie d = b loo dstr e a m = to t a rg et or g a n s
, Endocrine Glands in the human body:
1. H ypo th a la m u s
HYPOTHALAMUS
P a rt of b r a i n
Loc a tio n = a b o v e p it u it a r y gl a n d
Hor m o n es se cr ete d = A n ti - d i u r etic h or m o n e ( A DH)
= O x y toci n
gland
Anti-diuretic hormone (ADH):
Pro d u c e d = h y p ot h a l a m us
BUT stor e d + r ele a se d fro m p it u it a r y
T a r g et or g a n = colle cti n g d u cts = n e p h ro n i n ki d n e y
F u n ctio n = os m or e g u l a tio n = r e g u l a tes a m t. H2 O = b loo d
= r a ises b loo d p r ess u r e
C o n se r v i n g w a te r
↳ os m or e c e p tors i n h y p ot h a l a m us b loo d v esse ls
↳ d ete ct = i n cr e a se d of os m ol a rit y
↳ lo w H2 O le v els of b loo d
↳ h y p ot h a l a m us = r esp o n ds = r ele a se A DH
↳ if b o d y = d e h y d r a te d =
↳ m or e H2 O = r ele a se d i n to b loo d
↳ fro m colle cti n g d u cts of ki d n e y
↳ less w a te r = lost i n u ri n e
V ic e v e rs a for w h e n = too m u c h w a te r i n b loo d
Oxytocin:
Pro d u c e d = h y p ot h a l a m us
BUT = stor e d + r ele a se d fro m p it u it a r y
T a r g et or g a n = u te r us
= b r e a st tissu e
F u n ctio n = co n trols c h il d b irt h
↳ u te r us co n tr a ctio n
= co n trols l a ct a tio n
↳ m a m m a r y gl a n d co n tr a ctio n
↳ = m ilk ej e ctio n = b r e a st f e e d i n g
= co n trols a sp e cts of h u m a n b e h a v io u r
↳ “c u d d le c h e m ic a l”
↳ e g. m ot h e r - i n f a n t b o n d i n g
se x u a l a ro us a l
