Endocrine System
Lect # 2
Pituitary & Hypothalamic hormones
Prof Kumlesh K. Dev
Department of Physiology
Chapter 4 Principles of Neural and Hormonal Communication
Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning
What we cover today – Glands
Summary
What we cover today – Hormones
Summary
Posterior Pituitary
1. Oxytocin
y
2. Vasopressin
(Antidiuretic
hormone, ADH)
Hypothlamus
9 Thyrotropin-Releasing
9.
Th
t
i R l
i hormone
h
(TRH)
10. Corticotropin-Releasing hormone (CRH)
11. Gonadotropin-releasing hormone (GnRH)
12. Prolactin-releasing hormone (PRH)
13. Prolactin-inhibiting hormone (PIH)
(dopamine)
14. Growth-hormone releasing hormone
(
(GHRH)
)
15. Growth-hormone inhibiting hormone (GHIH)
(somatostatin) (SS)
Anterior Pituitary
y
3. Growth hormone (GH)
4. Thyroid stimulating hormone
(TSH)
5 Adreno-corticotropic
5.
hormone (ACTH)
6. Lutenising hormone (LH)
7. Follicle-stimulating hormone
(FSH)
8. Prolactin
•
Melanocyte stimulating hormone
(MSH)
Neuroendocrine System
Hypo/Pituitary
 M
Many physiological
h i l i l ffunctions
ti
are co-regulated
l t d
by the nervous system and the endocrine
system
 Study of this relationship is the focus of
neuroendocrinology
 Neuroendocrinology primarily concerns the
way the brain regulates pituitary hormone
secretion
Hypothalamus and Pituitary
Hypo/Pituitary
•
•
•
•
•
•
hypothalamus-pituitary: major unit of endocrine system
integrates nervous and endocrine systems
pituitary function depends on hypothalamus
pituitary (1 cm) lies at base of brain below hypothalamus
it is connected byy nerve fibers and blood vessels
regulates function of
–
–
–
–
–
–
thyroid
y
adrenal
reproductive glands
somatic growth
lactation
water metabolism
Hypothalamus and Pituitary
Hypo/Pituitary
 hypothalamus lies at base of
brain
 pituitary
p
y connects to base of
brain by infundibular stalk
 anterior pituitary: epithelial
structure develops from
Rathke’s pouch
 posterior pituitary: neural
p from floor of
structure develops
midbrain, consists of nerve fibers
that run from hypothalamus to
anterior
t i pituitary
it it
anterior pituitary
posterior pituitary
9 Major Pituitary Hormones: Summary
Pituitary
Site of Production
Hormone
Function
Posterior lobe
Vasopressin (anti
(anti-diruetic
diruetic hormone ADH)
Promotes water retention
Oxytocin
Stimulates milk ejection
Growth Hormone (GH)
Stimulates growth
Adrenocorticotropic hormone (ACTH)
Stimulates adrenal cortex
Thyroid stimulating hormone (TSH)
Stimulates thyroid gland
Prolactin (Prl)
Stimulates lactation
Luteinizing hormone (LH)
Stimulates gonads
Follicle stimulating hormone (FSH)
Stimulates gonads
Melanocyte stimulating hormone (MSH)
Darkens skin
Anterior Lobe
Intermediate lobe
Posterior Pituitary
Pituitary
• along with hypothalamus
forms neuroendocrine
system
y
• an outgrowth of
hypothalamus
yp
composed
p
of
neural tissue
• stores two peptide
hormones in axonal ends
• release Oxytocin and
Vasopressin (Antidiuretic
hormone, ADH or APV)
Production of Vasopressin & Oxytocin
Pituitary
• nerve cell bodies in of
hypothalamus
• peptides are packaged into
vesicular granules
• granules transported down
posterior lobe
axons into p
• peptide is released from
terminal ((similar to
neurotransmitter release)
Vasopressin
Oxytocin
y
Oxytocin (1)
Pituitary
• during birth, estrogen rises
• uterus produces oxytocin
receptors
• oxytocin contracts uterus
• synthetic oxytocin induces
labour
• also has weak antidiuretic
action resulting in water
retention (may cause pre
preeclampsia)
• oxytocin
y
also helps
p in smooth
muscle contractions which
cause release of milk
• oxytocin may regulate brain
function…
Vasopressin/ADH (2)
Pituitary
• controls water content
• acts on distal nephron and collecting tubules in kidney
• effects mediated by G protein coupled receptors
– V1 (vasoconstriction), V2 (Kidney), V3 (brain)
• promotes
t insertion
i
ti off water
t channels
h
l into
i t luminal
l i l
membrane to increase water permeability
• iin Di
Diabetes
b t - failure
f il
off ADH secretion
ti or reduced
d
d sensitivity
iti it
of kidney to ADH (antidiuretic hormone) may occur
• Analogues for clinical use
– Vasopressin; desmopressin (nasal spray, enuresis);
terlipressin (control of bleeding); felypressin (adjunct to
local anaesthetic)
Vasopressin/ADH (2)
Pituitary
• controls blood volume
• acts on kidney to increase water
reabsorption in distal tubule
• increased blood volume
– sensed byy stretch receptors
p
in heart
atrium
– signal to hypothalamus
Hypothalamus
+ ve
- ve
Vasopressin
Osmo
Receptor
Stretch
Receptor
– decreased vasopressin production
- ve
• decreased blood osmolarity
– reduced activity of hypothalamic
osmoreceptors
– reduces vasospressin secretion
+ ve
increased
blood vol
9 Major Pituitary Hormones: Summary
Pituitary
Site of Production
Hormone
Function
Posterior lobe
Vasopressin (anti
(anti-diruetic
diruetic hormone ADH)
Promotes water retention
Oxytocin
Stimulates milk ejection
Growth Hormone (GH)
Stimulates growth
Adrenocorticotropic hormone (ACTH)
Stimulates adrenal cortex
Thyroid stimulating hormone (TSH)
Stimulates thyroid gland
Prolactin (Prl)
Stimulates lactation
Luteinizing hormone (LH)
Stimulates gonads
Follicle stimulating hormone (FSH)
Stimulates gonads
Melanocyte stimulating hormone (MSH)
Darkens skin
Anterior Lobe
Intermediate lobe
Anterior Pituitary
Pituitary
• epithelia-derived upgrowth
from roof of oral cavity
• secretes tropic and direct
hormones
• anterior pituitary hormones
are regulated by
hypothalamic hormones
Anterior Pituitary Cell Types
Pituitary
 cells producing these hormones are specialized
 generally each cell type produces mainly one hormone
 cells named according to hormone they produce
 somatotrophs make growth hormone (somatotrophin)
 lactotrophs
p ((mammotrophs)
p ) make p
prolactin
 thyrotrophs make TSH
 corticotrophs
ti t
h make
k ACTH (corticotrophin)
( ti t hi )
Six Anterior Pituitary Hormones (3-8)
Pituitary
Hypothalamus
Anterior Pituitary
Growth
Hormone (GH)
Thyroid
stimulating
hormone (TSH)
AdrenoAdrenocorticotropic
(ACTH)
many target
organs
Thyroid gland
Adrenal cortex
growth, anabolic
actions
Thyroid Hormone
((T3.T4))
cortisol
Prolactin
(non--tropic)
(non
suckling (+ve)
mammary glands
d
dopamine
i (-ve)
( )
breast growth,
milk secretion
Luteinising
hormone (LH)
FollicleFolliclestimulating
hormone (FSH)
Ovaries/Testes
progesterone &
estrogen
g
(ovulation &
luteinisation)
estrogen
(development of
ovarian follicles)
testosterone
sperm production
Characteristics of hypothalamic
releasing
g hormones
Hypothalamus
• secretion
ti in
i pulses
l
• act on specific membrane receptors (G-protein coupled)
• regulate
– Hyperplasia (cell number):
• Stimulates cell division
• Inhibits apoptosis
p p
– Hypertrophy (cell size):
• Stimulates protein synthesis
• Inhibits protein breakdown
Seven Hypothalamic Hormones (9-15)
Hypothalamus
Hypothalamic
synthesis
y
CRH
TRH
PRH
PIH
GnRH
d
dopamine
i
(LH releasing
GHRH
hormome LHRH)
CorticotropinReleasing
hormone
ThyrotropinReleasing
hormone
Posterior Pituitary
oxytocin
ADH
storage & secretion
Breast
uterus
Kidney
blood
vessels
Hypothalamic
Prolactinreleasing
hormone
Prolactininhibiting
hormone
Gonadotropinreleasing
hormone
Growthhormone
inhibiting
hormone
Growthhormone
releasing
hormone
Anterior Pituitary
ACTH
TSH
Prolactin
FSH
LH
GH
AdrenoAdrenocorticotropic
hormone
Thyroid
stimulating
hormone
(non--tropic)
(non
FollicleFolliclestimulating
hormone
Luteinising
hormone
Growth
Hormone
Adrenal
cortex
Thyroid
gland
mammary
glands
cortisol
Thyroid
Hormone
(T3.T4)
breast
growth, milk
secretion
many
target
organs
Ovaries
/Testes
progesterone
& estrogen
ovulation &
luteinisation
estrogen
(develop
ovarian
follicles)
testosterone
sperm
production
Anterior Pit
Pituitary
itar
Posterior Pituitary
GHIH
somatostatin
growth,
anabolic
actions
Hypothalamus-Pituitary Control
Summary
Hypothalamus
TRH, CRH,
TRH
CRH LRH
GnRH, SS,
Dopamine
Dopamine
Oxytocin
Vasopressin
Anterior
Intermediate
Posterior
TSH, ACTH, GH
FSH, LH, Prl
MSH
Portal
Vessels
Pituitary
Systemic
Circulation
Hypothalamus-Pituitary Overview
Summary
What we cover today – Hormones
Summary
Posterior Pituitary
1. Oxytocin
y
2. Vasopressin
(Antidiuretic
hormone, ADH)
Hypothlamus
9 Thyrotropin-Releasing
9.
Th
t
i R l
i hormone
h
(TRH)
10. Corticotropin-Releasing hormone (CRH)
11. Gonadotropin-releasing hormone (GnRH)
12. Prolactin-releasing hormone (PRH)
13. Prolactin-inhibiting hormone (PIH)
(dopamine)
14. Growth-hormone releasing hormone
(
(GHRH)
)
15. Growth-hormone inhibiting hormone (GHIH)
(somatostatin) (SS)
Anterior Pituitary
y
3. Growth hormone (GH)
4. Thyroid stimulating hormone
(TSH)
5 Adreno-corticotropic
5.
hormone (ACTH)
6. Lutenising hormone (LH)
7. Follicle-stimulating hormone
(FSH)
8. Prolactin
•
Melanocyte stimulating hormone
(MSH)