Download The Anterior Pituitary

The Pituitary
Hormones
2-May-17
Pituitary Gland
1
Functional Anatomy
 Pituitary gland
3rd
ventricle
made up of
– Anterior lobe
• Originated from
Rathke’s pouch
(pharyngeal
epithelium)
Rathke’s
pouch
– Posterior lobe
Posterior
lobe
• Originated from
outgrowth of 3rd
ventricle
Anterior
lobe
Intermediate
lobe
2-May-17
Pituitary Gland
2
Functional Anatomy
 Also include the
3rd
ventricle
intermediate lobe
Rathke’s
pouch
Posterior
lobe
Anterior
lobe
Intermediate
lobe
2-May-17
Pituitary Gland
3
Relationship of Pituitary
to Hypothalamus
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypophysiotropic
hormones
secreted
Superior
hypophysial
artery
Posterior
pituitary
hormones
vein
2-May-17
 Embryo-logically
– Posterior lobe arise
as evagination of the
floor of 3rd ventricle
– It is made up of
axons that arise
from cell bodies
Anterior
pituitary
hormones
Pituitary Gland
• Supraoptic
• Paraventricular
– Hypothalamo –
hypophysial tract
4
Relationship of Pituitary
to Hypothalamus
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypophysiotropic
hormones
secreted
 Embryo-logically
– Anterior &
intermediate lobes
– Arise from Rathke’s
pouch
• Evagination from the
roof of pharynx
Superior
hypophysial
artery
Posterior
pituitary
hormones
vein
2-May-17
Anterior
pituitary
hormones
Pituitary Gland
5
Relationship of Pituitary
to Hypothalamus
 There are neural
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypophysiotropic
hormones
secreted
connections
– Hypothalamus
– Posterior lobe
 Nerves originate
from
Superior
hypophysial
artery
Posterior
pituitary
hormones
vein
2-May-17
– Supra-optic nucleus
– Paraventricular
nucleus
Anterior
pituitary
hormones
Pituitary Gland
6
Relationship of Pituitary
to Hypothalamus
 There is also
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypophysiotropic
hormones
secreted
Superior
hypophysial
artery
vascular
connections
between
– Hypothalamus
– Anterior pituitary
Posterior
pituitary
hormones
vein
2-May-17
Anterior
pituitary
hormones
Pituitary Gland
7
Portal – Hypophysial
Vessels
 Form direct
Supra optic
nucleus
vascular link
between
Hypothalamic
neurosecretions
Primary
plexus
capillaries
in median
eminence
Superior
hypophysial
artery
– Hypothalamus
– Anterior pituitary
 Arise from branch
Portal
hypophysial
vessels
of
Posterior
pituitary
hormones
vein
2-May-17
– Carotid artery
– Circle of willis
Capillaries
of anterior
pituitary
Pituitary Gland
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Portal – Hypophysial
Vessels
 Primary plexus
– Fenestrated
capillaries
– Penetrate median
eminence
Supra optic
nucleus
Hypothalamic
neurosecretions
Primary
plexus
capillaries
in median
eminence
Superior
hypophysial
artery
 Portal vessels arise
Portal
hypophysial
vessels
Posterior
pituitary
hormones
Vein
2-May-17
Capillaries
of anterior
pituitary
from median
eminence
– End into capillaries
of anterior pituitary
Pituitary Gland
9
Portal – Hypophysial
Vessels
 Hormones secreted
Supra optic
nucleus
by hypothalamus
Hypothalamic
neurosecretions
– Released in median
eminence
– Carried by blood
through
Primary
plexus
capillaries
in median
eminence
Superior
hypophysial
artery
Portal
hypophysial
vessels
Posterior
pituitary
hormones
Vein
2-May-17
• The portal
hypophysial vessels
to
• Anterior pituitary
Capillaries
of anterior
pituitary
Pituitary Gland
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Cells of the Anterior
Pituitary
 Usually there is one type of cell for
– Each major hormone produced by
the anterior pituitary
 The following are types of cells
found in the ant. Pit gland
– Somatotropes(30% of all cells of Ant.
Pit )
• Secrete GH
2-May-17
Pituitary Gland
11
Cells of Anterior Pituitary
 Corticotropes (20% of all cell
types)
– Secrete adrenocorticotropic
hormones(ACTH)
 Thyrotropes
– Secreter thyroid stimulating
hormone (TSH)
2-May-17
Pituitary Gland
12
Cells of Anterior pituitary
 Gonadotropes
– Secrete gonadotropic hormones
• Luteinizing hormone (LH)
• Folicle stimulating hormone (FSH)
 Lactotropes
– Secrete prolactin (PRL)
2-May-17
Pituitary Gland
13
Anterior Pituitary
Hormones
 Thyroid stimulating hormone
(TSH) [thyrotropin]
– Stimulates thyroid gland
• Growth
• Secrete thyroid hormones (thyroxin)
– Control rates of most chemical reactions of
the body
2-May-17
Pituitary Gland
14
Anterior Pituitary
Hormones
 Adrenocorticotrophic hormone
(ACTH) [corticotropin]
– Stimulates growth of adrenal cortex
• Zona fasciculata
• Zona reticularis
– Stimulate secretion of
• Adrenocortical hormones
• Affect metabolism of
– Glucose, protein & fat
2-May-17
Pituitary Gland
15
Anterior Pituitary
Hormones
 Growth hormone (GH)
– Somatotropin (STH)
 Accelerates body growth
– Protein formation, cell
multiplication, cell differentiation
 Stimulates secretion of (IGF-1)
insulin like growth factors
– Liver and other tissues
2-May-17
Pituitary Gland
16
Anterior Pituitary
Hormones
 Follicle stimulating hormones
(FSH) stimulates
– Ovarian follicles growth in females
– Spermatogenesis in males
 Luteinizing hormone (LH)
stimulates
– Ovulation and luteinizing of ovarian
follicles in females
– Testosterone secretion in males
2-May-17
Pituitary Gland
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Anterior Pituitary
Hormones
 Prolactin (PRL)
– Stimulate secretion of milk by
mammary glands
– Promote maternal behaviour
 - lipotropin (-LPH)
2-May-17
Pituitary Gland
18
Intermediate Lobe
Secretions
 Intermediate lobe secrete
– Melanotropin or intermedin
• Stimulate melanin synthesis in humans
• Expand melanophore
– Fish, amphibians, reptiles
2-May-17
Pituitary Gland
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Intermediate Secretions
 Melanotropin or intermedin include
– -melanocyte stimulating hormone (MSH)
–  - melanocyte stimulating hormone (MSH)
–  - melanocyte stimulating hormone ( MSH)
  - lipotropin ( - LPH)
– Corticotropin like peptide from
intermediate lobe
2-May-17
Pituitary Gland
20
Posterior Lobe Hormones
 Anti-diuretic hormone (ADH)
Vasopressin
– Promote water retention by kidneys
– Vasopressor
 Oxytocin
– Milk ejection
– Contraction of pregnant uterus
2-May-17
Pituitary Gland
21
Control of Anterior
Pituitary Secretions
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary
2-May-17
Secretions
of Anterior
pituitary
 Hypothalamus
– Secrete releasing or
inhibiting hormones
• In the median
eminence
 These are
transported via the
hypothalamic
hypophysial portal
system
– Anterior pituitary
Pituitary Gland
22
Control of Anterior
Pituitary Secretions
 Control the
Hypothalamus
Hypophysiotropic
hormones
secretion of
anterior pituitary
secretion
Hypothalamic
hypophysial portal
system
Anterior
pituitary
2-May-17
Secretions
of Anterior
pituitary
Pituitary Gland
23
Control of Anterior
Pituitary Secretions
 The releasing &
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary
2-May-17
inhibitory hormones
include
– Corticotrophin
releasing hormone
(CRH)
• Stimulate release of
adrenocorticotropin
hormone (ACTH)
Secretions
of Anterior
pituitary
Pituitary Gland
24
Control of Anterior
Pituitary Secretions
 Thyrotropin releasing
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary
2-May-17
hormone (TRH)
– Cause release of TSH
 Growth hormone
releasing hormone
(GRH)
– Cause release of GH
 Growth hormone
Secretions
of Anterior
pituitary
inhibiting hormone
(GIH)
– Inhibit release of GH
Pituitary Gland
25
Control of Anterior
Pituitary Secretions
 Leutenizing hormone
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary
2-May-17
Secretions
of Anterior
pituitary
releasing hormone
(LHRH)
– Cause release of LH
 Gonadotropin
releasing hormone
(GnRH)
– Cause release of LH,
FSH
Pituitary Gland
26
Control of Anterior
Pituitary Secretions
 Prolactin inhibiting
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary
2-May-17
factor (PIF)
– Cause inhibition
of prolactin
secretion
Secretions
of Anterior
pituitary
Pituitary Gland
27