FEEDBACK REGULATION IN THE ENDOCRINE SYSTEM

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FEEDBACK REGULATION IN THE ENDOCRINE SYSTEM
FEEDBACK INHIBITION
BRAIN
(hypothalamus)
(automatic cruise control)

CHEMICAL NATURE OF HORMONES
hypothlamic
releasing
Amino Acids
regulating
or

factors
inhibitory
thyroid homone
epinephrine
norepinephrine
Peptides
oxytocin
vasopressin (ADH)
pituitary
gland
circulating
tropic
Proteins
hormones
hormones

(inhibition)
(stimulation)
insulin
glucagon
prolactin
Steroids
testosterone
estrogen
corticosterone

endocrine gland
TARGET TISSUE
OR SYSTEMIC RESPONSE
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ENDOCRINE GLANDS, TISSUES AND HORMONES
Discreet Organs
Integrated Tissues
anterior pituitary
ovaries
somatotropic hormone (STH)
estrogen
gonadotropic hormone (GH)
progesterone
thyroid stimulating hormone (TSH)
adrenocorticotropic hormone (ACTH)
testes (interstitial cells)
follicle stimulating hormone (FSH)
leutinizing hormone (LH)
testosterone
prolactin
pancreas (islets of Langerhans)
intermediate lobe (pituitary)
insulin
melanocyte stimulating hormone (MSH)
glucagon
posterior pituitary
kidney (juxtaglomerular apparatus)
oxytocin
renin
vasopressin (ADH)
erythropoetin
gastrointestinal tract (APUD cells)
pineal gland
melatonin
secretin
cholecystokinen
thyroid gland
gastrin
thyroid hormone (T3 T4)
enteroglucagon
calcitonin
placenta
parathyroid gland
gonadotropin
parathyroid hormone
estrogen
progesterone
adrenal cortex
aldosterone
cortisol, aldosterone
adrenal medulla
epinephrine, norepinephrine
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THYROID AND PARATHYROID GLANDS
thyroid
cartilage
isthmus
superior
thyroid
parathyroid
artery
gland
lobe
of
thyroid
gland
parathyroid
glands
inferior
thyroid
thyroid
follicles
artery
trachea
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THYROID FOLLICLES
capillaries
follicular epithelium
Thyroid Follicles
(simple cuboidal)
thyroid follicle
follicular colloid
Colloid
follicles model
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SYNTHESIS OF THYROID HORMONE
fenestrated
CH2O
capillary
triiodothyronine(T3)
tyrosine
tetraiodothyronine(T4)
iodine
calcitonin
parafollicular cell
(ultimobranchial)
or C cell)
thyroglobulin
tri and tetraiodothyronine
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THYROID FOLLICLE ULTRASTRUCTURE
colloid
cap
C cell
C cell
follicular
cells
cap
cap
colloid
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THYROID ACTIVITY STATES
NORMAL
HYPOTHYROID
HYPERTHYROID
iodine-deficiency
toxic or exopthalmic
goiter
goiter
(cretinism, myxedema)
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PARATHYROID GLANDS
oxyphil cells
thyroid
follicle
capillary
chief cells
oxyphil cells
chief (principle)
cells
(parathormone)
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PARATHYROID FUNCTION
PARATHYROID
stimulates
parathormone
GLANDS
lowers
blood
calcium
(negative
inhibits
feedback)
1. stimulates osteoclasts
(bone resorption)
inhibits
raises blood
2. reduces kidney excretion
calcium
of calcium
suppresses
3. increases intestinal
osteoclast
adsorption of calcium
activity
(negative feedback)
THYROID
calcitonin
GLAND
Parathormone and Calcitonin
are antagonistic hormones
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ADRENAL GLANDS
phrenic
dorsal
capsular
artery
aorta
capillary
plexus
left adrenal
gland
abdominal
vein
inferior
middle
adrenal
adrenal
artery
artery
kidney
suprarenal
vein
adrenal
cortex
adrenal
ureter
suprarenal
medulla
vein
renal
renal
vein
artery
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ADRENAL GLAND - CORTEX AND MEDULLA
ADRENAL GLAND PANORAMIC
CORTEX AND MEDULLA
cortex
medulla
medulla
cortex
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ADRENAL CORTEX ZONATION
capsule
zona
Mineral Corticoids (e.i. aldosterone)
reticularis
(clusters)
(salt and water balance)
cortex
zona
fasciculata
Glucocorticoids (e.i. corticosterone)
(columns)
(carbohydrate metabolism,
suppression of the immune
system and inflammation)
zona
reticularis
Glucocorticoids
(network)
(possibly sex hormones)
chromaffin
epinephrine and
cells

norepinehprine
medulla
adrenalin
ganglion
cells
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ADRENAL CORTEX ZONES
capsule
zona glomerulosa
zona fasiculata
zona reticularis
medulla
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NEUROENDOCRINE SECRETION IN THE ADRENAL
MEDULLA
sympathetic
ganglion
cell
synpases
axon
norepinephrine
cell
chromaffin cell
synapse
(2 types-
epinephrine
fenestrated
norepinephrine
capillary
epinephrine
cell
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ADRENAL MEDULLA
zona reticularis
cortex
medulla
ganglion cell
chromaffin cells
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PITUITARY GLAND (HYPOPHYSIS)
paraventricular
nucleus
supraoptic
nucleus
hypothlamic
area
optic
chiasma
infindibulum
pars tuberalis
pars nervosa
pars distalis
pars intermedia
posterior
anterior
lobe
lobe
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PITUITARY GLAND PANORAMICS
infindibulum
infindibulum
pars nervosa
pars nervosa
pars distalis
pars
tuberalis
infindibulum
pars
distalis
pars
nervosa
pars intermedia
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ANTERIOR LOBE (PARS DISTALIS)
Basophils (10)
1. thyrotropes (TSH)
2. gonadotropes
acidophil
(LH,FSH,ICSH)
3. corticotropes (ACTH)
basophil
chromophobe
Chromophobes
Acidophils (40)
(reserve
undifferentiated
1. somatotropes (STH)
cells)
2. mammotropes
(LH, prolactin)
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ANTERIOR LOBE ULTRASTRUCTURE
fenestrated
capillary
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PARS INTERMEDIA (INTERMEDIATE LOBE)
Rathkes cysts (MSH-melanocyte
(eptheloid)
stimulating hormone)
PARS NERVOSA
RATHKES CYSTS
colloid
PARS INTERMEDIA
PARS DISTALIS
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PARS NERVOSA
hypothalamus
paraventricular
supraoptic
nucleus
nucleus
infindibulum
hypothalamo-
hypophyseal
tract
pituicyte nucleus
(HHT)
axons
Herring bodies
(neurophysin
carrier protein)
pituicytes
capillary
(neuroglial
cells)
Herring body
Oxytocin
Vasopressin (ADH)
(stimulates mammary
(vasoconstrictor, decreases
secretion, contracts
urine volume by retention
uterine wall)
of water)
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PARS NERVOSA - ULTRASTRUCTURE
HERRING BODIES
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PINEAL GLAND
BRAIN SAND
PINEAL GLAND PANORAMIC
PINEALOCYTES