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Hypophysis- Anterior Pituitary

Hypophysis- Anterior Pituitary. Prof. K. Sivapalan. Location. It is located in Sella Turcica , under Diaphragma Sella . It weighs 0.5g. In pregnancy it hypertrophies to 1g. 75% of the gland is anterior lobe- anterior pituitary. 25% is posterior pituitary. Development.

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Hypophysis- Anterior Pituitary

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  1. Hypophysis-Anterior Pituitary Prof. K. Sivapalan

  2. Location. • It is located in SellaTurcica, under DiaphragmaSella. • It weighs 0.5g. • In pregnancy it hypertrophies to 1g. • 75% of the gland is anterior lobe- anterior pituitary. • 25% is posterior pituitary. Anterior Pituitary

  3. Development. • Rathke's pouch- anterior pituitary. • Floor of the third ventricle- posterior pituitary. Anterior Pituitary

  4. Anterior Pituitary.[Adenohypophysis] Anterior Pituitary

  5. Blood supply • Anterior lobe: superior hypophysial artery and Hypothalamic Hypophysial Portal system from hypothalamic nuclei. Anterior Pituitary

  6. ACTH • Single chain, 39 amino acids, parts resembling MSH and stimulates Melanocyte activity. • Half life- 3-4 minutes. • Regulation of secretion- studied under glucocorticoids. • ACTH and β-LPH- lipotropin are synthesized as one molecule and split before release. • Lipotropin resembles Endophins and Enkephalins which act like opiates. • ?use in stress. Anterior Pituitary

  7. Gonodotrophins- FSH + LH. FSH- follicular stimulating hormone. • Glycoprotein, 25000mw, a and b chains. • Action on testis and ovaries. • Secretion at puberty. LH- Luteinizing hormone. • Glycoprotein, 40000mw, a and b chains. • Action on testis and ovaries. • Secretion starts at puberty. Anterior Pituitary

  8. TSH • Glycoprotein, 30000mw, a and b chains. • Control- TRH • Action on thyroid gland. Anterior Pituitary

  9. Prolactin. • Structure- similar to GH. • Human Prolactin- 198 amino acids. • Control- Prolactin Inhibiting Hormone (Dopamine, - only inhibitory factor from hypothalamus) • Chlorpromazine stimulates secretion by reducing Dopamine receptors. • Regulation- • exercise and stress- surgical or psychological. • stimulation of nipple by nerves to hypothalamus. Anterior Pituitary

  10. Anterior Pituitary

  11. Actions of Prolactin • Secretion of milk in breast prepared by estrogen, progesterone, growth hormone and corticoids. • At high concentrations, similar metabolic actions as Growth Hormone. • (Ejection of milk -by oxytocin) • Hyperprolactinaemia: • Inhibition of menstruation in females • Impotence and hypogonadism in males. • Mechanism not known. ? Inhibition of gonadotropins by nervous stimuli from breast or prolactin Anterior Pituitary

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