Download Anterior Pituitary

Ok, we talked about the Posterior Pituitary,
but what about the Anterior Pituitary?
Anterior Pituitary
!
Hormones released by
hypothalamus regulate secretion
of hormones by synthesized and
stored in the anterior pituitary itself
"
!
Hormone Cascade Pathways
1.
2.
3.
4.
5.
AP Biology
Hypothalamic hormones are either releasing hormones or
inhibiting hormones promoting or inhibiting release of
Anterior Pituitary’s hormone
Signal to brain stimulates hypothalamus
Hormone secreted stimulates or inhibits anterior pituitary
hormone
Anterior Pituitary hormone acts on a target endocrine tissue
Stimulates secretion of yet another hormone
Exerts systemic (body-wide) metabolic or developmental effects
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Anterior Pituitary
hypothalamus
thyroid-stimulating
hormone
(TSH)
Thyroid gland
ic
otrop
ortic CTH)
c
o
n
adre one (A
horm
Kidney
tubules
gr
ow
th
Adrenal
cortex
stimulating
hormone (FSH)
& luteinizing
hormone (LH)
L)
PR
n(
cti
ola
pr
Tropic Hormones:
Regulate the function
of OTHER endocrine
cells or glands
ho
rm
on
e
(G
H)
posterior antidiuretic
pituitary hormone
(ADH)
anterior
pituitary m
o
el
an xytoc
in
oc
yt
est
gonadotropic
im
ul
hormones:
at
in
follicleg
ho
rm
(M on
SH e
)
Uterine
muscles &
mammary
gland
Melanocyte
in amphibian
Bone
and muscle
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Testes
Ovaries
Mammary
glands
in mammals
Nontropic hormones of the anterior pituitary
Homology in hormones
What does this tell you about these hormones?
How could these hormones have different effects?
same gene family
gene duplication?
prolactin
mammals
milk
production
birds
fat
metabolism
fish
amphibians
salt &
water
balance
delays
metamorphosis
& maturation
growth
hormone
! Melanocyte stimulating hormone
"
"
! Prolactin
"
growth
& development
Regulates the activity of pigment-containing cells in the
skin of amphibians, fish, and reptiles
Inhibits hunger in humans
"
Target cells = mammary glands in mammals
Stimulates mammary gland growth and milk synthesis in
mammals
! Suckling stimulates oxytocin
release from posterior pituitary
which stimulates milk release
Regulates fat metabolism and
reproduction in birds
" Delays metamorphosis in
amphibians
"
Regulates salt and water
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balance in freshwater fishes
"
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Growth Hormone (GH)
- Nontropic & tropic
! Growth hormone releasing
hormone (GHRH) produced
by hypothalamus
" Growth hormone
secreted by anterior
pituitary gland
! Major target = Liver
! Releases insulin-like
growth factors (IGFs)
which circulate in blood
and directly stimulate
bone and cartilage
growth
! GH also raises blood
glucose levels
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Growth Hormone (GH) Abnormality
! Gigantism = overproduction
of GH during childhood
! Acromegaly =
overproduction of GH during
adulthood
"
"
“Acro” = extreme
“mega” = large
! Pituitary Dwarfism =
underproduction of GH
in childhood
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Thyroid Gland
! Thyroid gland produces thyroid
hormones
" Increase metabolism and cells O2
uptake
" Releases more thermal energy
! Raises body temperature
" Regulated by feedback loops
! Hypothalamus
"
Secretes TRH = TSH-releasing
hormone
Regulating
metabolism
! Target cells in anterior pituitary
! Anterior Pituitary
"
Secretes TSH = thyroid stimulating
hormone (a tropic hormone!!!)
! Target cells in thyroid gland
! Thyroid
"
produces thyroxine hormones (T3 &
T4)
! Derived from amino acid tyrosine
! Triiodothyronine (T3) has 3 I atoms
! Thyroxine (T4) has 4 I atoms
"
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Malfunctions
! M
metabolism & development
! bone growth
! mental development
! metabolic use of energy
! blood pressure & heart rate
! muscle tone
! digestion
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! reproduction
thyroxines
Goiter
Iodine deficiency causes thyroid to enlarge as it
tries to produce thyroxine
+
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tyrosine
+
iodine
tyrosine
+
iodine
AP
Biology thyroxines
Stress Response - The Adrenal Gland
! Composed of two glands
"
"
Adrenal cortex (outer)
Adrenal medulla (central)
! Responds to nervous input
(neural signal)!
Quick Response
"
Medulla
! Secretes catecholamines in
response to stress
! Class of amine hormones
synthesized from amino
acid tyrosine
! Epinephrine (adrenaline)
& norepinephrine
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(noradrenaline)
ACTH - Tropic Hormone
!
Adrenal Cortex Responds to hormonal inputs
Stressful stimuli causes hypothalamus to secrete
"
The Stress Response - Adrenal Gland
! Epinephrine (adrenaline) &
norepinephrine (noradrenaline)
Increase rate of glycogen breakdown in
liver and skeletal muscles
! Promote glucose release by liver cells
" Stimulate release of fatty acids from fat cells
" Increase heart rate and stroke volume
" Dilate bronchioles in lungs
! Increase rate of oxygen delivery
to tissues
" Cause constriction of some vessel
! Shunt blood away from skin,
digestive organs, kidneys
! Increase blood supply to heart,
brain and skeletal muscles
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"
Corticosteroids
! Glucocoritcoids
Affect glucose metabolism
Promote glucose synthesis from noncarbohydrate sources like proteins
Cortisol causes skeletal muscle to
breakdown muscle proteins
Anti-inflammatory effect as they
suppress parts of immune system
"
"
Corticosteroid Releasing
Hormone (CRH)
Cause anterior pituitary to
"
"
"
secrete Adrenal Cortex
Tropic Hormone (ACTH)
!
"
Targets Adrenal Cortex
"
Glucocorticoids
Mineralocorticoids
Used to treat arthritis
! Mineralocorticoids
ACTH enter bloodstream Secretes corticosteroids
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!
Affect mineral metabolism
Aldosterone function in ion and water
homeostasis in the blood
!
!
AP Biology !
Low blood volume or pressure leads to
production of angiotensin II w
Stimulates secretion of aldosterone
Stimulates cells in kidney to reabsorb
sodium ions and water form filtrate
Effects of stress on a body
Stress
Nerve
Spinal cord
signals
(cross section)
Hypothalamus
Releasing
hormone
Nerve
cell
adrenal medulla
secretes epinephrine
& norepinephrine
Anterior pituitary
Blood vessel
Nerve cell
ACTH
Adrenal
gland
ME
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AP
Calcium Homeostasis
!
Calcium homeostasis
"
1. Glycogen broken down to glucose;
increased blood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood flow patterns, leading
to increased alertness & decreased
Biology digestive & kidney activity
"
Thyroid makes
calcitonin hormone
!
Ca+2
is needed for nerve function, muscle contraction,
blood clotting, etc…
! Calcium
regulation
functions via
antagonistic
hormones
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Effects of epinephrine and norepinephrine:
Calcium regulation
normal blood range is 9 to 11 mg%
!
Kidney
A
LL
U
D (A) SHORT-TERM STRESS RESPONSE
"
Lowers Ca2+ levels in blood
# Causes Ca2+ to be
deposited into bone
# Reduces intestinal
absorption of Ca2+
# Reduces Ca2+ uptake by
kidney from urine
Parathyroid makes
parathyroid hormone
Raises Ca2+ levels in blood
# Stimulates release Ca2+
from bone
# Increase Ca2+ uptake by
intestine into blood
# Increase Ca2+ uptake
AP Biology out of urine by kidney
!
Adrenal cortex
secretes
mineralocorticoids
& glucocorticoids
CO
(B) LONG-TERM STRESS RESPONSE
RT
Effects of
mineralocorticoids:
Effects of
glucocorticoids:
1. Retention of
sodium ions &
water by kidneys
1. Proteins & fats broken
down & converted to
glucose, leading to
increased blood
glucose
2. Increased blood
volume & blood
pressure
2. Immune system
suppressed
EX
Endocrine System Control
Feedback
Regulation of Blood Calcium
calcitonin
" kidney
reabsorption
of Ca++
thyroid
Ca++ deposited
in bones
high
blood calcium level
! Ca++ uptake
in intestines
(10 mg/100mL)
low
activated Vitamin D
bones
release Ca++
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! kidney
reabsorption
of Ca++
parathyroid
parathyroid hormone (PTH)