DR AMNA TAHR ASSISTANT PROFESSOR PHYSIOLOGY DEPARTMENT KEMU HORMONE A hormone is a chemical substance produced in particular parts of organisms by specific cells glands andor tissues and then transported to other parts of the body with the intent of influencing a variety of ID: 621850
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Slide1
HORMONE PRODUCTION AND STORAGE
DR AMNA TAHR
ASSISTANT PROFESSOR
PHYSIOLOGY DEPARTMENT
KEMUSlide2
HORMONE
A
hormone
is a
chemical substance
produced in particular parts of organisms by specific cells, glands, and/or tissues and then transported to other parts of the body, with the intent of influencing a variety of physiological and behavioral activities, such as the
processes
of
digestion
,
metabolism
,
growth
,
reproduction
and
mood
control. Slide3
ENDOCRINE SYSTEM
The
endocrine system
is a ductless system
referring to the collection of
cells
,
glands
, and
tissues
of an organism that
secrete
hormones
directly into the bloodstream
to control the organisms' physiological and behavioral activities
.
The endocrine system is in contrast to the
exocrine system
, which secretes its chemicals using
ducts
.
The word endocrine derives from the Greek words "
endo
" meaning inside, within, and "
crinis
" for secrete. Slide4
ENDOCRINE ORGANSSlide5
MAJOR CLASSES OF HORMONES
1-
Protein
and
peptides
including hormones secreted by anterior and posterior pituitary, the pancreas , parathyroid gland
2-
Steroids
secreted by the adrenal cortex, the ovaries
, testes
3-
Derivative
of
the
amino
acid
tyrosine
, secreted by thyroid gland , adrenal medullae.Slide6
HORMONE PRODUCTION AND STORAGE
Polypeptide and protein hormone are stored in secretory vesicles until needed.
Steroid hormones are usually synthesized from cholesterol and not stored.
Amine hormones are derived from tyrosineSlide7
FEED BACK CONTROL OF HORMONE SECRETION
Negative feedback mechanism
Is most commonly applied principle for regulating hormone secretion
It prevents over activity of the hormone system
Is self -limiting
A hormone has biologic actions that, directly or indirectly , inhibit further secretion of the hormoneSlide8
FEED BACK CONTROL OF HORMONE SECRETION
Positive feedback
mechanism
is rare
Is explosive and self – reinforcing
Surges of hormone can occur with positive feed back
A hormone has biologic actions that, directly or indirectly, cause more secretion of the hormoneSlide9
MECHANISM OF ACTION OF HORMONE
Hormone receptors and their activation
Location of receptors for different hormones
In or on the surface of cell membrane for protein , peptide and catecholamine hormones
In the cell cytoplasm for steroid hormones
In the cell nucleus for thyroid hormonesSlide10
INTRACELLULAR SIGNALING AFTER HORMONE RECEPTOR ACTIVATION
Ion Channel –linked receptors
G-Protein-linked Hormone receptors
Enzyme-linked hormone receptorsSlide11
Ion Channel –linked receptorsSlide12
G-Protein-linked Hormone receptorsSlide13
Enzyme-linked hormone receptorsSlide14
SECOND MESSANGER MECHANISM
AdenylCyclase
–
cAMP
second messenger system
Cell Membrane Phospholipid second messenger system
Calcium -
Calmodulin
second messenger systemSlide15
AdenylCyclase
–
cAMP
second messenger systemSlide16
Cell Membrane Phospholipid second messenger systemSlide17
Mechanism of interaction of lipophilic hormonesSlide18