Pituitary hormones

1. 29-Apr-24 Pituitary Gland 1
The Pituitary
Hormones

2. 29-Apr-24 Pituitary Gland 2
Functional Anatomy
 Pituitary gland
made up of
– Anterior lobe
• Originated from
Rathke’s pouch
(pharyngeal
epithelium)
– Posterior lobe
• Originated from
outgrowth of 3rd
ventricle
3rd
ventricle
Rathke’s
pouch
Anterior
lobe
Posterior
lobe
Intermediate
lobe

3. 29-Apr-24 Pituitary Gland 3
Functional Anatomy
 Also include the
intermediate lobe
3rd
ventricle
Rathke’s
pouch
Anterior
lobe
Posterior
lobe
Intermediate
lobe

4. 29-Apr-24 Pituitary Gland 4
Relationship of Pituitary
to Hypothalamus
 Embryo-logically
– Posterior lobe arise
as evagination of the
floor of 3rd ventricle
– It is made up of
axons that arise
from cell bodies
• Supraoptic
• Paraventricular
– Hypothalamo –
hypophysial tract
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypo-
physiotropic
hormones
secreted
Superior
hypophysial
artery
vein
Posterior
pituitary
hormones
Anterior
pituitary
hormones

5. 29-Apr-24 Pituitary Gland 5
Relationship of Pituitary
to Hypothalamus
 Embryo-logically
– Anterior &
intermediate lobes
– Arise from Rathke’s
pouch
• Evagination from the
roof of pharynx
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypo-
physiotropic
hormones
secreted
Superior
hypophysial
artery
vein
Posterior
pituitary
hormones
Anterior
pituitary
hormones

6. 29-Apr-24 Pituitary Gland 6
Relationship of Pituitary
to Hypothalamus
 There are neural
connections
– Hypothalamus
– Posterior lobe
 Nerves originate
from
– Supra-optic nucleus
– Paraventricular
nucleus
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypo-
physiotropic
hormones
secreted
Superior
hypophysial
artery
vein
Posterior
pituitary
hormones
Anterior
pituitary
hormones

7. 29-Apr-24 Pituitary Gland 7
Relationship of Pituitary
to Hypothalamus
 There is also
vascular
connections
between
– Hypothalamus
– Anterior pituitary
Supra optic
nucleus
Hypothalamic
neurosecretions
Hypo-
physiotropic
hormones
secreted
Superior
hypophysial
artery
vein
Posterior
pituitary
hormones
Anterior
pituitary
hormones

8. 29-Apr-24 Pituitary Gland 8
Portal – Hypophysial
Vessels
 Form direct
vascular link
between
– Hypothalamus
– Anterior pituitary
 Arise from branch
of
– Carotid artery
– Circle of willis
Supra optic
nucleus
Hypothalamic
neurosecretions
Primary
plexus
capillaries
in median
eminence
Superior
hypophysial
artery
vein
Posterior
pituitary
hormones
Capillaries
of anterior
pituitary
Portal
hypophysial
vessels

9. 29-Apr-24 Pituitary Gland 9
Portal – Hypophysial
Vessels
 Primary plexus
– Fenestrated
capillaries
– Penetrate median
eminence
 Portal vessels arise
from median
eminence
– End into capillaries
of anterior pituitary
Supra optic
nucleus
Hypothalamic
neurosecretions
Primary
plexus
capillaries
in median
eminence
Superior
hypophysial
artery
Vein
Posterior
pituitary
hormones
Capillaries
of anterior
pituitary
Portal
hypophysial
vessels

10. 29-Apr-24 Pituitary Gland 10
Portal – Hypophysial
Vessels
 Hormones secreted
by hypothalamus
– Released in median
eminence
– Carried by blood
through
• The portal
hypophysial vessels
to
• Anterior pituitary
Supra optic
nucleus
Hypothalamic
neurosecretions
Primary
plexus
capillaries
in median
eminence
Superior
hypophysial
artery
Vein
Posterior
pituitary
hormones
Capillaries
of anterior
pituitary
Portal
hypophysial
vessels

11. 29-Apr-24 Pituitary Gland 11
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

12. 29-Apr-24 Pituitary Gland 12
Cells of Anterior Pituitary
 Corticotropes (20% of all cell
types)
– Secrete adrenocorticotropic
hormones(ACTH)
 Thyrotropes
– Secreter thyroid stimulating
hormone (TSH)

13. 29-Apr-24 Pituitary Gland 13
Cells of Anterior pituitary
 Gonadotropes
– Secrete gonadotropic hormones
• Luteinizing hormone (LH)
• Folicle stimulating hormone (FSH)
 Lactotropes
– Secrete prolactin (PRL)

14. 29-Apr-24 Pituitary Gland 14
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

15. 29-Apr-24 Pituitary Gland 15
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

16. 29-Apr-24 Pituitary Gland 16
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

17. 29-Apr-24 Pituitary Gland 17
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

18. 29-Apr-24 Pituitary Gland 18
Anterior Pituitary
Hormones
 Prolactin (PRL)
– Stimulate secretion of milk by
mammary glands
– Promote maternal behaviour
 - lipotropin (-LPH)

19. 29-Apr-24 Pituitary Gland 19
Intermediate Lobe
Secretions
 Intermediate lobe secrete
– Melanotropin or intermedin
• Stimulate melanin synthesis in humans
• Expand melanophore
–Fish, amphibians, reptiles

20. 29-Apr-24 Pituitary Gland 20
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

21. 29-Apr-24 Pituitary Gland 21
Posterior Lobe Hormones
 Anti-diuretic hormone (ADH)
Vasopressin
– Promote water retention by kidneys
– Vasopressor
 Oxytocin
– Milk ejection
– Contraction of pregnant uterus

22. 29-Apr-24 Pituitary Gland 22
Control of Anterior
Pituitary Secretions
 Hypothalamus
– Secrete releasing,
inhibiting hormones
• In the median
eminence
 These are
transported via the
hypothalamic
hypophysial portal
system
– Anterior pituitary
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary Secretions
of Anterior
pituitary

23. 29-Apr-24 Pituitary Gland 23
Control of Anterior
Pituitary Secretions
 Control the
secretion of
anterior pituitary
secretion
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary Secretions
of Anterior
pituitary

24. 29-Apr-24 Pituitary Gland 24
Control of Anterior
Pituitary Secretions
 The releasing &
inhibitory hormones
include
– Corticotrophin
releasing hormone
(CRH)
• Stimulate release of
adrenocorticotropin
hormone (ACTH)
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary Secretions
of Anterior
pituitary

25. 29-Apr-24 Pituitary Gland 25
Control of Anterior
Pituitary Secretions
 Thyrotropin releasing
hormone (TRH)
– Cause release of TSH
 Growth hormone
releasing hormone
(GRH)
– Cause release of GH
 Growth hormone
inhibiting hormone
(GIH)
– Inhibit release of GH
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary Secretions
of Anterior
pituitary

26. 29-Apr-24 Pituitary Gland 26
Control of Anterior
Pituitary Secretions
 Leutenizing hormone
releasing hormone
(LHRH)
– Cause release of LH
 Gonadotropin
releasing hormone
(GnRH)
– Cause release of LH,
FSH
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary Secretions
of Anterior
pituitary

27. 29-Apr-24 Pituitary Gland 27
Control of Anterior
Pituitary Secretions
 Prolactin inhibiting
factor (PIF)
– Cause inhibition
of prolactin
secretion
Hypothalamus
Hypophysiotropic
hormones
Hypothalamic
hypophysial portal
system
Anterior
pituitary Secretions
of Anterior
pituitary