Endocrine System Master Glands

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Endocrine System Master Gland(s)

• Modified from
• http//www2.kumc.edu/instruction/nursing/nrsg812/e
  ndocrine/
• Images from
• http//www.endocrineweb.com/
• gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookEND
  OCR.html

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Hypothalamus and Pituitary

• Pituitary has direct neural and blood connection
  to the hypothalamus
• Hypothalamus sends releasing factors to anterior
  pituitary
• Hypothalamus stimulates posterior pituitary via
  neural pathway

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Hypothalamus

• Hypothalamus can synthesize and release hormones
  from its axon terminals into the blood
  circulation.
• controls pituitary function and thus has an
  important, indirect influence on the other glands
  of the endocrine system.
• exerts direct control over both the anterior and
  posterior portions of the pituitary gland.
• regulates pituitary activity through two
  pathways a neural pathway and a portal venous
  pathway.

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Hypothalamus

• Neural pathways extend from the hypothalamus to
  the posterior pituitary lobe, where the hormones
  are stored and secreted.
• Portal venous pathways connect the hypothalamus
  to the anterior pituitary lobe, carry releasing
  and inhibiting hormones

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Pituitary Gland

• Pituitary Gland is located at the base of the
  skull in an indentation of the sphenoid bone.
• Is joined to the hypothalamus by the pituitary
  stalk (neurohypophyseal tract) and consists of
  the anterior pituitary and the posterior pituitary

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Anterior pituitary gland (adenohypophysis)

• Called the master gland, because its anterior
  lobe has direct control over the secretion of
• ADH - antidiuretic hormone (vasopressin)
• ACTH - adrenocorticotrophic hormone
• TTH - thyrotrophic hormone
• GH - growth hormone
• FSH - follicle stimulating hormone
• LH - leutinizing hormone

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Posterior pituitary

• Stores and secretes hormones made in the
  hypothalamus and contains many nerve fibers.
• ADH (Antidiuretic Hormone/Vasopressin), which
  controls the rate of water excretion into the
  urine
• Regulates Na K reabsorption in the kidneys
  this influences blood volume blood pressure
• Oxytocin, which, among other functions, helps
  deliver milk from the glands of the breast.

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Steroid Hormones

• Diffuse into cell and influence DNA
• Bind to a protein associated with DNA
• Cause DNA to increase synthesis of specific amino
  acids

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Feedback Loops

• The release of a hormone is often triggered by a
  change in the concentration of some substance in
  the body fluids.
• Each hormone has a corrective effect, eliminating
  the stimulus, which then leads to a reduction in
  hormone secretion.
• This process is called a negative feedback
  homeostatic control system to keep hormones at
  normal levels. (if levels increased it would be
  called positive feedback)

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Sources

• http//www.letsfindout.com/subjects/body/
• http//www.endocrineweb.com/whatisendo.html
• http//www.stmarys.medford.or.us/curriculum/bio/hb
  sm/glands/katie.htm
• http//www2.kumc.edu/instruction/nursing/nrsg812/e
  ndocrine/
• http//gened.emc.maricopa.edu/bio/bio181/BIOBK/Bio
  BookENDOCR.html
• http//www.novo-nordisk.co.uk/health/dwk/info/ency
  clopedia/1/3.asp