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NROSCI/BIOSC 1070
MSNBIO 2070
September 12, 2016
Control
2
Functions of Hormones
Hormones act on their target cells in one of
three basic ways:
1. Control the rate of enzymatic reactions
2. Control transport of molecules across cell
membranes
3. Control gene expression and synthesis
Types of Hormones
Peptides
Amino Acids
Steroids
Divisions of Pituitary
Anterior pituitary
(also called adenohypophysis)
True glandular tissue
Posterior pituitary
(also called neurohypophysis)
Extension of brain
Hypothalamic-Hypophyseal Portal System
Tropic Hormones — Control
the Release of Other
Hormones
Ultra Short
Loop Feedback
Short
Loop Feedback
Long Loop Feedback
Anterior
End Products
Pituitary
Hormones
Regulate
areTropic
Tropic
Hormone
Hormones
Secretion
Anterior Pituitary Hormones
Hormones of the Anterior Pituitary Gland
Hormone
Thyroid-stimulating hormone (TSH)
Target
Thyroid gland
Major Actions in Humans
Stimulates synthesis and secretion of thyroid hormones
Ovary
Stimulates growth of follicles and estrogen secretion
Testis
Acts on Sertoli cells to promote maturation of sperm
Follicle-stimulating hormone (FSH)
Ovary
Luteinizing hormone (LH)
Testis
Growth hormone (GH)
Prolactin
Adrenocorticotropic hormone
(ACTH)
b-lipotropin, b-endorphin
Stimulates ovulation of ripe follicle and formation of corpus luteum;
stimulates estrogen and progesterone synthesis by corpus luteum
Stimulates interstitial cells of Leydig to synthesize and secrete
testosterone
Promotes growth in stature and mass; stimulates production of
insulin-like growth factor (IGF-I); stimulates protein synthesis
No Known Tropic
Mammary glands Promotes milk secretion and mammillary growth Role
Most tissues
Adrenal Cortex
?
Promotes synthesis and secretion of adrenal cortical hormones
Physiologic role not established
Proopiomelanocortin
(POMC)
POMC is cleaved within a vesicle to form
ACTH, -Endorphin, LPH, and 16K
fragment
Hypophysiotropic Hormones: Control
Anterior Pituitary Secretions
Others likely exist, but have not been
discovered because of their low concentrations
in blood
What happens if feedback mechanisms
are dysfunctional?
Tumors can produce large amounts of hormones
without feedback regulation
Autoimmune diseases can damage receptors on
hormone-secreting cells, so they no longer
respond to tropic hormones
Intracellular signal transduction pathways can
become aberrantly altered, thereby affecting how
hormone-producing cells respond to tropic
hormones.
Posterior Pituitary Hormones
Arginine Vasopressin

Named as such because the first vasopressin discovered was from pig;
this hormone has a lysine instead of arginine as residue 8

Produces vasoconstriction when present in high concentrations (hence the
name)

Affects water reabsorption in kidney at lower concentrations, hence the
secondary name: antidiuretic hormone
Oxytocin

Triggers uterine contractions during birthing

Triggers milk release from mammary glands during suckling

May have roles in cardiovascular control and renal function (men and
women who are not of child-bearing age also synthesize oxytocin)
Posterior Pituitary
Hormones
Posterior pituitary hormones
are synthesized by neurons
in the paraventricular and
supraoptic nuclei of the
hypothalamus
These hormones are
released like
neurotransmitters when the
neurons fire
The release of the hormones
is dependent on the number
of neurons that fire and the
rate and duration of their
firing
Examples of Some Hormones
Hormon
e
ErythroEpinGastrin
poietin
ephrine
Insulin
TestosAldosterone
terone
LH
Where
Produce
d
Tubular
epithelial
G
cells of
Adrenal
Islets
of
cells
of
Leydig
stomach
medulla
LangerKidney
Cells
of
Adrenal
hans
Testis
cortex
Anterior
(mainly)
Pituitary
Effect
Stimu-lation
Stimulates
Enhances
Leydig
cells of
of
Stimulation
glucose
Many
effects
Stimulates
acid
Promotes
testis
red
bloodtocell
transport
mediated by
secretion
by
reabsorption
synthesize
&of
production
by
Production
many
binding
to +tissues;
stomach
Na
and
release
bone
marrow
maintenance
of
receptors
increases
excretion
of K+
testosterone;
male sexual
glucose
by
tubular
stimulates
characteristics
metabolism
epithelial
cells
of
estrogen
&and
storage
kidney
progesterone
secretion by
corpus luteum;
stimulates
ovulation
Peptides
and
High
plasma
Sympathetic
amino
acids
glucose
Hypoxia
of
nervous
in stomach;
levels,
tubular
system
enteric
epithelial
cells
hormone
influences
on+
LH
from
Increased
K
nervous
Adrenal
GIP,from
anterior
in
plasma,
GnRH
system
medulla
parasympituitary
Angiotensin
Hypo- II
pathetic
thalamus
activity
Inhibition
Somatostatin
and
None
SympaNone
low
pH in
TestosIncreased
thetic
stomach
terone,
None
Na+
in
activity
estrogen,
plasma
progesterone,
Inhibin