• size of a pea
• hangs by a stalk from the hypothalamus in the brain
• has 2 functional lobes: anterior - glandular tissue, posterior - nervous tissue
• often called the "master endocrine gland

Hormones of the Anterior Pituitary

• Characteristics
• proteins (or peptides
• act via second messenger systems (1st releasing hormone)
• regulated by hormonal stimuli, mostly neg. feedback

Hormones of the Anterior Pituitary

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• Growth Hormone
  • General metabolic hormone
  • Directed to growth of skeletal miscles, long bone
  • Determines final body size
  • Causes amino acids to be built into proteins
  • Causes fats to be broken down for an energy source

Hormones of the Anterior Pituitary

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Growth hormone (GH) disorders

• Pituitary Dwarfism - hyposecretion of GH during childhood
• Giantism results from hypersecretion of GH during childhood
• Acromegaly results from hypersecretion of GH durinng childhood

Hormones of the Anterior Pituitary

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• Prolactin (PRL)
  • Stimulates & maintains milk production following childbirth
• Adrenocorticotropic hormone (ACTH)
  • Regulates endocrine activity of the adrenal cortex

Hormones of the Anterior Pituitary

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• Thyroid-stimulating hormone (THS)
  • Influences growth & activity of the thyroid gland (Goiter)
• Gonadotropic honomes
  • regulate hormonal activity of the gonads
    • Follicle -stimulating hormone (FSH)
      • Stimulates: follicle develomnet in the ovaries, sperm development in testes
    • Luteinizing horone (LH)
      • Triggers: ovulatio of female egg, testosterone production in males

Hormones of the Posterior Pituitry

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• Oxytocin
  • Stimulates contractions of uterus during labor, sexual relations & breast feeding
  • Causes milk ejection in a nursing mother
  • Induces bonding with baby & mother

Hormones of the Posterior Pituitary

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• Antidiuretic hormone (ADH)
  • Inhibits urine production by promothing water reabsorption by the kidneys
  • In large amounts, causes vasoconstriction leading to increased blood pressure
  • Also known as vasopressin, typically in males

Thyroid Gland

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• Found at the base of the throat
• Consists of 2 lobes & a connecting isthmus
• Produces 2 hormones
  • Thyroid hormone
  • Calcitonin

Thyroid Gland - Hormone

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• Thyroid Hormone - Major Metabolic Hormone
  • Composed of 2 active iodine-containing hormones
    • Thyrosine (T4) - secreted by thyroid follicles, 4 iodine form, 95% of hormone produced
    • Tri-iodothyronine (T3) - conversion of T4 at target tissues, active fom

*we need iodine in our diets to keep the thyroid active