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Pituitary Gland - Anatomy & Physiology (view source)
Revision as of 11:13, 2 January 2011
, 11:13, 2 January 2011→Anterior Pituitary Gland
==Anterior Pituitary Gland==
==Anterior Pituitary Gland==
The anterior pituitary contains the '''pars distalis''', and the '''pars tuberalis'''. This part of the pituitary gland is controlled by ''releasing factors'' from the [[Hypothalamus - Anatomy & Physiology|hypothalamus]]. These factors reach the anterior pituitary via the '''hypophyseal portal system''', venous channels allowing direct passage between the hypothalamus and the pituitary gland. The anterior pituitary gland secretes two types of hormone:
1.'''Trophic hormones''': Stimulate a further endocrine gland E.g. TSH, ACTH, FSH, LH. These are then controlled by [[Negative Feedback - Anatomy & Physiology|negative feedback]], whereby the product of the downstream endocrine gland limits the release of the orginial stimulating hormone.
2.'''Direct-action hormones''': Act directly on non-endocrine tissues E.g. GH. There is no target gland, so release of these hormones is controlled by a balance of releasing and inhibitory factors from the hypothalamus. For example; GH is controlled by stimulatory '''somatocrinin''' (aka Growth Hormone Releasing Hormone) and inhibitory '''somatostatin'''.
===Pars Distalis===
===Pars Distalis===
The '''pars distalis''' contains 5 cell types which produce 6 hormones. '''Somatotropes''' and '''lactotropes''' are ''acidophillic''. '''Corticotropes, thyrotropes''' and '''gonadotropes''' are ''basophillic''.
The Pars Distalis contains 5 cell types which produce 6 hormones.
''Somatotropes'' and ''Lactotropes'' are '''Acidophillic'''.
''Corticotropes, Thyrotropes'' and ''Gonadotropes'' are '''Basophillic'''.
[[Image:Pituitary Gland - Pars Distalis - Acidophils and Basophils.jpg|center|thumb|350px|'''Pars Distalis''' ©RVC 2008]]
[[Image:Pituitary Gland - Pars Distalis - Acidophils and Basophils.jpg|center|thumb|350px|'''Pars Distalis''' ©RVC 2008]]