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The Pituitary Gland

The Pituitary Gland. The hypothalamus significantly influences the pituitary gland. Posterior pituitary. Hypothalamic releasing and inhibiting hormones are delivered to the anterior pituitary. The hypothalamus makes and releases the hormones of the posterior pituitary.

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The Pituitary Gland

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  1. The Pituitary Gland The hypothalamus significantly influences the pituitary gland Posterior pituitary Hypothalamic releasing and inhibiting hormones are delivered to the anterior pituitary The hypothalamus makes and releases the hormones of the posterior pituitary

  2. Pituitary (Hypophysis) • Posterior Pituitary – “neurohypophysis” • Anterior Pituitary – “adenohypophysis”  Oxytocin  Antidiuretic Hormone (ADH)  

  3. Anterior Pituitary – synthesizes 6 hormones. Growth Hormone (hGH) (also called Somatotropin)  Adrenocorticotropic Hormone (ACTH) (also called corticotropin)   Thyroid Stimulating Hormone (TSH)   Follicle Stimulating Hormone (FSH)  Luteinizing Hormone (LH)  Prolactin (PRL) 

  4. hGH – is the primary hormone that regulates overall body growth, also important in general metabolism.   ACTH – stimulates cortisol secretion from the adrenal cortex (the stress hormone!). Also promotes growth of adrenal cortex.  TSH – stimulates secretion of thyroid hormone and the growth of the thyroid gland. Important regulator of metabolic activity in the body.

  5. FSH – a) in females: stimulates growth and development of ovarian follicles, and promotes estrogen secretion.  b) in males: it is required for sperm production. LH – a) in females: responsible for ovulation and for luteinization. Regulates estrogen and progesterone.  b) in males: stimulates interstitial cells (in testes) to secrete testosterone. * called interstitial cell stimulating hormone (ICSH) PRL – enhances breast development and milk production in females. 

  6. Normal Growth • Growth hormone and other hormones • An adequate diet • Absence of stress • Genetics

  7. Growth Hormone • Severe hGH deficiency leads to dwarfism • Oversecretion of hGH in children leads to giantism • Oversecretion of hGH in adults leads to acromegaly

  8. The Hypothalamus-Pituitary-Adrenal Axis (HPA) The cortisolconnection

  9. Circadian Rhythm of Cortisol Secretion

  10. Cortisol • Promotes gluconeogenesis • Breakdown of skeletal muscle proteins • Enhances lipolysis (prevents glucose use) • Permissive – needed for NE vasoconstriction • Suppresses the immune system • Response to stressors – protective?

  11. Hypercortisolism • Adrenal tumor that secretes cortisol • Pituitary tumor that secretes ACTH e.g., Cushing’s disease (syndrome) ↑ glucose and ↓ protein Loss of muscle mass Characteristic fat deposits

  12. Hypocortisolism • Hyposecretion of all adrenal steroid hormones • Autoimmune destruction of adrenal cortex e.g. Addison’s disease ↓ glucose (hypoglycemia) Poor response to stress Lack of permissive action

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