Download Regulation of Hormone Secretion

Regulation of Hormone
Secretion
2-May-17
Regulation of Hormone Secretion
1
Negative Feedback
Mechanism
 Hormones
produce biological
effects
 On attaining sufficient magnitude
 Inhibit further secretion
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Regulation of Hormone Secretion
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Components of the
System
 (1)
A detector of the
 Actual
or threatened homeostatic
imbalance
 (2)
means of signaling secretion
 (3) the secretory cells
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Regulation of Hormone Secretion
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Components of the
System
 (4)
an end organ or
 Organ
capable of an appropriate
response to the hormone
 (5)
A means of promptly shutting
of secretion
 When
response becomes adequate to
restore homeostasis
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Regulation of Hormone Secretion
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Components of the
System
 In
simpler cases
 Parathyroid,

 In
-cells of the pancreas
Components 1, 2, 3, & 5 reside in the
same secretory cells
complex situation
 Thyroid
secretion
 Complex interactions between

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CNS, anterior pituitary gland & thyroid
gland
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Types of Imputes
 Most
hormones are released in
short burst
 With
no or little release in between
the bursts
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Regulation of Hormone Secretion
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Types of Imputes
Plasma concentration of hormones
may fluctuate rapidly over brief times
 Hormones also manifest 24 hrs cyclical
variation in their secretory pattern



Circadian pattern differ in different
hormones
Some are linked to sleep

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GH - during early period of sleep
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Control of Hormone
Secretion

Neurotransmitters
Plasma conc of
organic
nutrient
Another
hormone
Some of factors that
influence the
secretion of hormones
include


Endocrine
cell
Changes in
plasma conc of
mineral ions


Neurotransmitters
Another hormone
Changes in plasma conc
of nutrients
Changes in plasma conc
of mineral ions
Hormone
secretion
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Regulation of Hormone Secretion
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Control of Hormone
Secretion
 Endocrine
cells like neurons
 May
be subject to multiple
simultaneous inputs
 Sometimes opposing
 The
resulting output
 Rate

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of secretion of hormone
Reflect the integration of all these inputs
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Control by conc of
Nutrient
 Plasma glucose
conc

Insulin
secreting
cells
Hormone secretion is
controlled by


 INSULIN in
plasma
The function of the
hormone

 Action of
insulin by
target cells
Plasma conc of nutrient or
organic ions
To regulate in negative
manner


Plasma conc of nutrient or
ions
Controlling its secretion
 Plasma glucose
conc
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Regulation of Hormone Secretion
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Control by Neurons
 Hypothalamus
 Has
neural control over hormone
secretion by the posterior pituitary
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Regulation of Hormone Secretion
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Hypothalamic –
Hypophysial Axes
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypophysiotropic
hormones
secreted
Superior
hypophysial
artery
vein
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Posterior
pituitary
hormones
Anterior
pituitary
hormones

Secretory activity
of anterior
pituitary


Controlled by
hypothalamic
hormone
Secreted into
hypothalamic
hypophysial portal
system
Regulation of Hormone Secretion
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Hypophysial Portal
System
Supra optic
nucleus
Hypothalamic
neurosecretions

Median eminence

Hypophysiotropic
hormones
secreted
Superior
hypophysial
artery
vein
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

Posterior
pituitary
hormones
Specialized area of
hypothalamus
Located beneath the
3rd ventricle
It is a release center
for
hypophysiotropic
hormones
Anterior
pituitary
hormones
Regulation of Hormone Secretion
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Hypothalamic –
Hypophysial Axes
Limbic system

The hypothalamus

Hypothala
mus
Secrete releasing or
inhibiting hormone

Hypophys
iotropic
hormones
Adenohypophysis
Pit.
Tropic
hormones
Target gland
hormone
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

Hypophysiotropic
hormone
These act on the
anterior pituitary
Anterior pituitary
then secrete

Trophic hormone
Target
gland
Regulation of Hormone Secretion
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Hypothalamic –
Hypophysial Axes
Limbic system

Hypothala
mus
Hypophys
iotropic
hormones
The trophic
hormone then

Act on target gland

Secrete the hormone
Adenohypophysis
Pit.
Tropic
hormones
Target gland
hormone
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Target
gland
Regulation of Hormone Secretion
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Feedback Control Systems
Limbic system

Hypothala
mus
Hypophys
iotropic
hormones
Adenohypophysis
Pit.
Tropic
hormones
Target gland
hormone
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Target
gland
The unbound
circulating
hormone

Produced by target
gland



Inhibit hypothalamic
pituitary system
Cause  secretion of
pituitary tropic
hormone
Control the secretion
of target gland
Regulation of Hormone Secretion
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Feedback Control Systems
Limbic system
Negative feedback
control occur on 3
levels
 Long loop feedback

Hypothala
mus
Hypophys
iotropic
hormones

Adenohypophysis
Pit.
Tropic
hormones
Target gland
hormone
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
Peripheral gland
hormones or
Substrate arising
from metabolism
Target
gland
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Feedback Control Systems
Limbic system

Hypothala
mus
Can exert long-loop
feedback control on


Hypophys
iotropic
hormones
Adenohypophysis
Pit.
Tropic
hormones
Target gland
hormone
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
Hypothalamus
Anterior pituitary
Long-loop feedback
system


Usually are negative
feedback
But can be positive
feedback as well
Target
gland
Regulation of Hormone Secretion
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Feedback Control Systems
Limbic system

Hypothala
mus
Hypophys
iotropic
hormones
Adenohypophysis
Pit.
Tropic
hormones
Target gland
hormone
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Short-loop
feedback system


Negative feedback
can be exerted by
Anterior pituitary
hormone on the

Synthesis and
release of
hypothalamic
releasing or
inhibiting hormones
Target
gland
Regulation of Hormone Secretion
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Feedback Control Systems
Limbic system

Hypothala
mus
Hypophys
iotropic
hormones
Adenohypophysis
Ultra-short loop
feedback


Hypophysiotropic
hormones
Can inhibit their
own synthesis and
secretion
Pit.
Tropic
hormones
Target gland
hormone
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Target
gland
Regulation of Hormone Secretion
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