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Thyroid Gland - Pathology (view source)

Revision as of 13:55, 21 February 2011

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==Anatomy and Physiology==
 
==Anatomy and Physiology==
 
Anatomy and Physiology of the thyroid gland can be found [[Thyroid Gland - Anatomy & Physiology|here]].
 
Anatomy and Physiology of the thyroid gland can be found [[Thyroid Gland - Anatomy & Physiology|here]].
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==Functional Anatomy (summary)==
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The thyroid gland lies in the neck, in front of the upper part of the trachea.  Two types of hormones are produced:
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*Iodine-containing hormones: '''Tri-iodothyronine'''(T3) and '''Thyroxine''' (T4).  Thyroid hormones regulate the basal metabolic rate and are important in the regulation of growth of tissues, particularly nervous tissue.  Release stimulated by TSH from the pituitary.
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*'''Calcitonin''': Regulates blood calcium levels along with parathyroid hormone.  Acts to reduce blood calcium by inhibiting its removal from bone. 
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The majority of the gland is derived from a downgrowth of the foetal tongue.  The calcitonin producing cells are different and are derived from the fourth branchial pouch. 
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[[Image:Normal thyroid.jpg|right|thumb|125px|<small><center>'''Normal Thyroid'''. Courtesy of A. Jefferies</center></small>]]
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The throid gland is divided into follicles which are bounded by a single layer of cuboidal epithelial cells and a basement membrane.  Follicles contain a homogenous colloid material called '''thyroglobulin'''.  This is a store of thyroid hormones prior to secretion.  The thyroid gland is the only endocrine gland to store its hormone in large quantities. 
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In the active gland:
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*Colloid is diminished.
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*Epithelial cells are tall and columnar. 
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'''Parafollicular''' cells are found in clusters in the interfollicular space.  Also known as '''clear''' cells as their cytoplasm doesn't stain with H and E.
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These cells synthesise and secrete calcitonin in response to raised plasma calcium.
      
==Goitre==
 
==Goitre==
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