COMMUNICATION and INTEGRATION within the ORGANISM

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COMMUNICATION and INTEGRATION within the ORGANISM
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Some Comparisons between Endocrine and Neural
Communication Endocrine secrete chemical at
one site uses circulation to act at another
site Relatively slow Acts on many cells Can
sustain action for long periods of
time Neural nerve cell to nerve cell or
nerve cell to effector cell (e.g.,
muscle) Extremely fast can travel 50-80
m/sec Very distinct effects Connection often
acts on one cell
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There are 3 kinds of hormones

• PEPTIDE HORMONES -- many water soluble
  cell impermeant

e.g., CATECHOLAMINE HORMONES ( neurotransmitters)
Adrenaline
Nor-adrenaline
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Chemical (Hormonal) communication between cells
occurs through receptors
requires an intracellular messenger
Surface
(also known as 2nd messenger)
A
Water soluble hormones
(1st messenger)
B
Steroid hormones
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STEROID HORMONES from adrenal cortex gonads
HO
CHOLESTEROL
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STEROID HORMONE ACTION
membrane permeable
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Peptide AA-derivative Hormone Action
Operate through surface receptors transduction
via 2nd messengers
2nd Messenger Concept
An intracellular message is transduced from
signals at the external surface
Some important 2nd messengers
1. cAMP cyclic AMP
2. IP3 inositol trisphosphate
3. Ca calcium ions
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Lets start with the cAMP 2nd messenger pathway
PDE
AC
AMP
cAMP
ATP
phospho- diesterase
adenylate cyclase
O
O
O
O
AC
PDE
-O-P-O-
-O-P-O-P-O-P-O-
O
O
O
O
O
O
O--P
O
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PDE
AC
cAMP
ATP
AMP
phospho- diesterase
adenylate cyclase
Ways to stimulate cAMP levels
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Particularly Protein Kinase A (PKA) (a
protein kinase that is activated by cAMP)
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Protein Kinase A
Cell Response
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Ca2 and IP3 as intracellular messengers
Cell Response
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Thyroid gland
b cells - insulin a cells - glucagon
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We need to keep blood glucose level constant
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INSULIN-GLUCAGON antagonism regulation of
blood glucose
muscle fat
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INSULIN-GLUCAGON antagonism regulation of
blood glucose
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Hormonal control of calcium homeostasis in mammals
Another example of antagonistic hormones
calcitonin
PTH parathyroid hormone
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Hormones of the Hypothalamus Pituitary Gland
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Hormones of the Hypothalamus Pituitary Gland
(contd)
1
often called releasing hormones
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ACTH adrenocorticotropic hormone
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Stress and the Adrenal Gland
STEROIDS
nor-adrenalin
adrenalin
fight or flight