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Assist prof. of Medical Physiology

Learn about the causes and manifestations of disorders of the adenohypophysis, such as gigantism, dwarfism, and acromegaly. Explore the effects of excess growth hormone and its impact before and after epiphyseal union in adults and children.

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Assist prof. of Medical Physiology

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  1. Physiology of Endocrine Assist prof. of Medical Physiology Abdelaziz M. Hussein

  2. Disorders of Adenohypophysis

  3. Disorders of Growth Hormone Excess GH Decreased GH Before Union of epiphysis After Union of epiphysis In adults In children Loss of some body proteins Gigantism Dwarfism Acromegaly

  4. Disorders of Excess GH Causes: • Hyperplasia or • Tumor of the somatotrop cells (adenoma) Manifestations: • The manifestations depends upon, if it occursbefore or after the union of the epiphyses. A) Gigantism:↑ed GH before the union of the epiphyses. B) Acromegaly: ↑ed GH after the union of the epiphyses or in adults

  5. Gigantism Def: • Condition caused by excess GH before union of epiphysis Manifestations: 1)Marked elongation of bonesbut in a relative proportion. 2) Overgrowth of soft tissuese.g. the muscles & viscera.

  6. Gigantism in a 36-year-old woman. Her companions are normal.

  7. Gigantism Manifestations: 3) Hyperglycemia and increased MR. 4) Hypogonadism: • Gonads and accessory sex organs remain infantile due to￬edgonadotropins secretion • GH secreting cellsencroach upon the other cells.

  8. S S S S G S S S S T S S S S M G S S S S S M T S S C Pituitary tumor causes compression and atrophy of gonadotrophes

  9. Gigantism Manifestations: 5) Headache due to pressure on Sella Turcica and visual disturbances (Bitemporal hemianopia) due to pressure of the growing tumor on the optic chiasma. 6) These patients are often mentally subnormal

  10. Bitemporal hemianopia

  11. Acromegaly Def: • Condition caused by excess GH after union of epiphysis in adults Manifestations: • The bones become thicker and deformed; the ms and viscera also enlarge • Generalizedcoarsening of the features due to: • Thick skin and SC tissues. • Enlargement of the head, hands and feet. • Prognathism: the lower jaw enlarged & protrudes forward, and separated teeth.

  12. Spade hand

  13. Acromegaly Manifestations: • 3) Kyphosis due to thickening of the vertebrae. • 4) Hyperglycemia and glucosuria. • 5) Raised BMR.

  14. Acromegaly Manifestations: • 6) Hypogonadism. • 7) Some patients have visual fields defects due to pressure of the tumor on optic chiasma. • Increased intracranial tension lead to headache & vomiting. • 8) Hirsutism (increased body hair). • 9) Gynaecomastia and may be galactorrhea

  15. Acromegaly Treatment: • 1) Surgical: removal of tumor • 2) Medical: • Somatostatin or • Somatostatin synthetic compounds e.g. Octreotide and lanreotide

  16. Dwarfism Def: • Condition caused by deficiency of GH in children Manifestations: a) Short stature due to rapid closure of the epiphyses leading to proportionate reduction of all body sizes. b) The growth rate of soft tissues is reduced, but mild obesity is common. • The patient looks much younger than his age.

  17. Dwarfism Manifestations: c) Normal Mental growth usually. d) Low metabolic rate & episodes of hypoglycemia due to lack of insulin antagonism by GH. e) Normal Sexual maturationin cases of isolated GH deficiency. • Few dwarfs show hypogonadism and the gonads, external sexual organs and characters remain infantile Infantilism . NB: Deficiency of GH in adults has no physical signs

  18. Causes of Short Stature • 1) Cretinism: Thyroid hypofunction in infants. • 2) Precocious puberty: • in cases of hypergonadism in children, which leads to early closure of the epiphyses. • 3) Gonadal dysgenesis e.g. Turner’s syndrome where an XO chromosomal pattern instead of XX or XY. • 4) Bone and metabolic diseases. • 5) Constitutional delayed growth in many cases no evident cause for stunted growth is found.

  19. Turner syndrome

  20. Disorders of Prolactin Hormone Excess prolactin Decreased prolactin Due to Due to Hypothalamic dysfunctions Pituitary tumors Destruction of ant. Pituitary G.

  21. Excess Prolactin Manifestations: • High prolactin inhibit GnRH and pituitary gonadotropins resulting in; • a) In women, • Loss of menses (amenorrhea), • Anovulation and infertility. • Galactorrhea: lactation unassociated with pregnancy • Decreasedlibido.

  22. Excess Prolactin Manifestations: • b) In men, 1) Decreased: • testosterone secretion. • sperm production. • libido. 2) Stimulation of breast enlargement (Gynaecomastia) & Galactorrhea is rare.

  23. Excess Prolactin • Diagnosis : • by a high prolactin blood level. • Treatment: by: A) Surgical removal of the tumor or B) Dopaminergic drugs to reduce prolactin secretion

  24. Deficiency of Prolactin • In women produces inability to lactate. • No other clinical consequences are known.

  25. Panhypopituitrism (Simmond`s Disease) Results from destruction of the ant pituitary, leads to: • Severe deficiency of its hormones and • Atrophy of the thyroid and adrenal glands and of the gonads. Manifestations: 1. In children: lead to infantilism. • failure of growth and of sexual maturity. 2. In adults, the lack of trophic hormones results in • hypofunction of the target endocrine glands with relative hyperinsulinism.

  26. Panhypopituitrism (Simmond`s Disease) Manifestations: • a) Thyroid gland (Myxoedema) • b) Adrenal cortex(hypocorticism or ‘Addison’s disease) → leading to ms weakness, loss of weight, hypoglycaemia and dehydration. • c) The gonads (hypogonadism).

  27. Panhypopituitrism (Simmond`s Disease) Manifestations: d) Loss of weight and severe wasting of muscles (cachexia) due to: • loss of appetite (anorexia) and absence of anabolic effect of GH and androgens. e) Premature senility: • dry skin and wrinkled with early graying of hair • so the patient looks older than his age.

  28. Panhypopituitrism (Simmond`s Disease) Manifestations: f) Hypoglycaemia due to: • relative increase insulin level • lack the effects of antagonistic hormones. g) Skin colour becomes lighter due to: • anaemia and • deficiency of ACTH and beta-MSH.

  29. Posterior Pituitary Neurohypophysis

  30. Posterior Pituitary • Thousands of nerve fibres connect the hypothalamus, (supra-optic & para-ventricular nuclei), with the post pituitary. • The crude extract of the post lobe is called pituitrinthat contains 2 hormones: 1). Antidiuretic hormone (ADH), also called vasopressin or pitressin. 2). Oxytocin(or pitocin) hormone.

  31. Posterior Pituitary Synthesis and Storage: • Oxytocin & ADH, are synthesized in the hypothalamus and stored in granules with a binding protein (neurophysin) • Neurophysin-1 for oxytocin • Neurophysin-2 for antidiuretic hormone. • Granules pass down the axons through hypophyseal tracts to the nerve endings in post pituitary. • The terminal swellings of nerve endings are called ‘Herring bodies’.

  32. Release of Posterior Pituitary Hormones • When a nerve impulse is transmitted from the cell body in hypothalamus down the axon: • Depolarizes the terminal Herring body. • Ca+ influx into the Herring bodyinduce hormone release by exostosis, and enters the adjacent capillary.

  33. ADH (Vasopressin)

  34. ADH (Vasopressin) Source: • Mainly from supraoptic hypothalamic nucleus Chemistry: • Peptide hormone 9 a.a.

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