My lesson for 1st MBBS

1. Pituitary encapsulated in the SELLA TURCICA
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3. • Anterior Pituitary ectodermal in origin
• From Rathke’s Pouch
• Posterior Pituitary
• Neurohypophysis
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Pituitary development

4. Parts of Pituitary gland
• Anterior lobe or
ADENOHYPOPHYSIS
– Pars Distalis
– Pars intermedia
– Pars tuberalis
• Posterior lobe or
NEUROHYPOPHYSIS
– Pars Posterior
– Infundibular Stem
– Median Eminence
• Intermediate lobe or
PARS INTERMEDIA
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6. Histology of Pituitary• Adenohypophysis
– Chromophobes
– Chromophils
– Acidophilic cells
– Somatotrophs
– Mammotrophs or Lactotrophs
– Basophilic Cells
– Corticotrophs
– Thyrotrophs
– Gonadotrophs
– Folliculostellate cells
• Neurohypophysis
– Unmyelinated nerve fibers
– Pituicytes
– Glial cells
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8. Blood Supply of Pituitary Gland
The Hypophyseal portal system
is a blood system of vessels in
the brain that connects the
hypothalamus with the anterior
pituitary.
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9. HYPOTHALAMO-
HYPOPHYSEAL
PORTAL SYSTEM
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10. Hypothalamic-Pituitary
Relationship
1. Hypothalamo-hypophyseal
tract
– Herring bodies from axons of
supraoptic & paraventricular nuclei
– Vasopressin
– Oxytocin
2. Tubero-infundibular tract or Hypothalamo-
Hypophyseal portal system
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11. Relationship between Anterior
Pituitary & Hypothalamus
• Tubero-infundibular tract or Hypothalamo-
Hypophyseal portal system
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13. Hypothalamic-Pituitary Unit
Regulates
• Growth
• Lactation
• Fluid homoeostasis
• Thyroid function
• Adrenal Gland function
• Reproduction
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14. AnteriorPituitary
Hormones
• Hormones of growth hormone family
– Growth Hormone
– Prolactin
• Glycoprotein hormones family
– Thyroid stimulating hormone
– Luteinizing hormone
– Follicular-stimulating hormone
• Pro-opiomelanocortin peptides
– Adrenocorticotropic Hormone
– Melanocyte stimulating hormone
– β-lipoprotein
– β-endorphin
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15. Mastergland
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16. Growth Hormone
Somatotropin
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17. GROW
TH
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18. Abnormalities of
Anterior Pitutitary
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19. Common clinical pituitary disorders
Hypopituitarism
Abnormalities of Growth Hormone
Prolactin deficiency
Cushing’s syndrome
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20. Hypo
pituit
arism
Effects of Hypopituitarism
1. GH deficiency
2. Gonadotropin secretion
3. Thyrotropic hormone secretion
4. Adrenocorticotropin hormone
deficiency
5. Effect on water metabolism
6. Effect on insulin sensitivity
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21. Abnormalities of Growth Hormone secretion
Hyper-secretion
Gigantism
Acromegaly
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22. Gigantism
 Hypersecretion of GH
BEFORE the closure of
epiphysis of long bones
 Abnormal height
 Large hands and feet
 Coarse facial features
 Bilateral Gynaecomastia
 Loss of libido / impotence
 Hyperglycemia >> deficiency
of insulin due to degeneration
of beta cells of pancreas
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23. PITUITARY TUMOR
Features
 Headache
 Visual field defects
 Cranial nerve palsies
 Enlargement of pituitary fossa
with destruction of CLINOID
process
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24. Acro
meg
aly
 Excess of GH AFTER epiphyseal closure of
long bones; excess growth where cartilage
persists
 Acromegalic face
 Prognathism
 Acral part abnormalities
 Kyphosis
 Excessive growth of internal organs
 Cardiomegaly, hepatomegaly,
splenomegaly, renomegaly
 Increased sympathetic activity
 Sweating / hypertension
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26. Hyposecretion of GH
 Deficiency of GH in Childhood
Dwarfism
 Deficiency of GH in adulthood
Mild anemia
Reduction in muscle mass
Hypoglycemia
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27. Dwarfism
 Endocrinal causes
 GH Deficiency / Pituitary dwarf
 Panhypopituitarism
 Hypothyroid dwarf
 Cushing’s syndrome
 Non-Endocrinal causes
 Familial dwarfism
 Achondroplasia
 Nutritional (malnutrition / Malabsorption)
 Chromosomal abnormalities (Turner’s)
 Psychological dwarfism (Kasper-Hauser’s Syndrome)
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28. GH related dwarfism
1. Pituitary dwarfism
2. African Pygmies
3. Laron dwarfism
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29. StructureSynthesisSecretion • 191 amino acids
• MW of 2000
• Acidophilic cells
• Increased secretion
– Sleep, stress, hormones
related to puberty,
starvation, exercise,
hypoglycemia
• Decreased secretion
– Somatostatin,
somatomedins, obesity,
hyperglycemia &
pregnancy03/09/2019 Jaideep J Rayapudi, Physiology PIMS 29

30. RegulationofGHsecretion
1. Hypothalamic control
2. Negative feedback control
3. Other factors
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31. Hypothalamiccontrol
• GHRH
– Hypoglycemia
– Emotions
– Slow wave phase of sleep
– Amino acids like arginine
– Ghrelin (Growth hormone
releasing peptide)
• GHIH
– Hyperglycemia
– High plasma free fatty acids
(FFA)
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32. Negative feedback
i. Somatomedins
i. Somatomedin A, which is another name for
insulin-like growth factor 2
ii. Somatomedin B, which is derived from vitronectin
iii. Somatomedin C, which is another name for
insulin-like growth factor 1
ii. GH
iii. GHRH (ultra short loop)
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33. Other factors controlling GH secretion
• Thyroxine & cortisol stimulate GH
• Insulin represses GH gene expression
• Placental GH & placental lactogen decrease GH during
later part of pregnancy
• Obesity causes decreased response to GHRH
• Neurotransmitters – DA, NE, Ach, Serotonin, GABA,
Histamine increase GHRH & decrease somatostatin
• Oestradiol- increase GH
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35. GH
• Receptors present
on cell membrane
– liver & adipose tissue
• Mechanism of
action
• Insulin like growth
factors
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36. Act
ion
sof
GH
1. Growth promoting actions of GH
– Effect on cartilage – proliferation of chondrocytes
– Effect on bones – stimulates osteoblastic activity
2. Metabolic actions of GH
i. Effects on protein metabolism- anabolic
ii. Effects on fat metabolism - catabolic
iii. Effects on carbohydrate metabolism- increase
gluconeogenesis
iv. Effects on mineral metabolism- bone
mineralization
3. Effects on lactation – like prolactin03/09/2019 Jaideep J Rayapudi, Physiology PIMS 36

37. Human Prolactin
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38. Prolactin
• Single peptide chain
• Secretion starts from 8th week of
pregnancy
– Also from placenta, amniotic fluid
• Affected by oestrogen
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39. Hypothalamiccontrol
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40. Hypothalamic control
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41. Factors enhancing the release of prolactin
• TRH
• Stress - increases
• Dopamine antagonists - phenothiazines
• Oxytocin – stimulates acidophilic cells
• Sectioning of pituitary stalk – portal circulation
disturbed
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42. Physiological effects of Prolactin
1. Breast growth
– Alveolar tissue, mammary vessels
2. Lactogenic effect
– In pregnancy - Suppressed by high estrogen
and progesterone
– After parturition – oxytocin increased
3. Suppression of ovarian cycle in nursing
mothers
– Inhibits GnRH >> low FSH & LH
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43. Assignment >>
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44. Good Afternoon!!
 Posterior Piruitary!!
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