The hypothalamo-adenohypophyseal axis: anterior pituitary Flashcards
What is the alternative name for the pituitary gland?
HYPOPHYSIS
Why is the pituitary gland know as the master gland?
Regulates a series of other and it controls many body systems
What is the alternate name for the anterior pituitary gland?
adenohypophysis
What is the alternate name for the posterior pituitary gland?
neurohypophysis
Describe the embryology of the pituitary gland?
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The 2 components of the pituitary gland develop from different structures. There is a upward growth from the buccal cavity called Rathke’s pouch towards a downward growth from the base of the brain - these two growths combine to make one gland.
So the pituitary gland has 2 components, 1 secretory part derived from the buccal cavity the adenohypophysis and 1 neural part, the neurohypophysis, made up of nerve axons derived from the base of the brain.
Glandular Tissue - Buccal Cavity (pharyngeal region of the mouth) has an extension that starts growing upwards Nervous Tissue - there is a downwards movement of tissue from the developing hypothalamus .
These two tissues then fuse and normally lose contact with the rest of the buccal cavity. So one part of the pituitary is derived from glandular tissue (adenohypophysis) and the other part is derived from neural tissue (neurohypophysis)
Besides hormonal effects, what can a tumour of the pituitary gland cause and why can it do this?
The optic chiasm is near the anterior pituitary and this will become relevant n Y2 Endocrinology lectures when you learn that tumours of the pituitary gland can cause visual disturbance. add pic
What are groups of nueronal cell bodies known as?
Groups of neuronal cell bodies are called nuclei.
The hypothalamus surrounds one of the ventricles of the brain What is the name of this ventricle?
3rd Ventricle
What is the region of median eminence?
Median Eminence = an area that lies between the top of the pituitary stalk and the hypothalamus add pic
A different population of neurons have shorter axons and these terminate in the part of the hypothalamus which abuts the pituitary gland Name this region?
Region of median eminence
What is the body of the anterior putituary gland known as?
Pars distalis is the body of the anterior pituitary add pic
What is the part of the pituitary gland that wraps around the pituitary stalk?
the pars tuberalis is the part of the anterior pituitary which wraps around the pituitary stalk add pic
What is the Neurohypophysis mainly made up of ?
What does the Adenohypophysis consist of?
Neurohypophysis- (mainly nerve axons and nerve terminals) Adenohyphysis- Secretory cells add pic
Where do some of the axons coming from the hypothalmic nuclei terminate at?
Neurohypophysis and the Region of median eminence add pic
Describe the THE HYPOTHALAMIC – HYPOPHYSIAL PORTAL CIRCULATION? Start at the superior hypophyseal artery
It starts with blood arriving in the SUPERIOR hypophyseal artery and this enters a capillary network in the median eminence.
From this capillary network, blood drains to a second capillary network in the anterior pituitary – a portal network.
From the secondary capillary system, blood would flow out into the venous system via the cavernous sinus.
This system is critical for control of anterior pituitary function. The importance of the HYPOTHALAMIC – HYPOPHYSIAL PORTAL CIRCULATION is that it can carry messages from the hypothalamus to the anterior pituitary gland
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What is a portal network?
A portal network is where blood from the systemic circulation drains from one capillary network to another before returning to the heart.
What does fenestrated mean?
Fenestrated capillary is a leaky capillary
What in the hypothalmic-hypophysial portal circulation is fenestrated?
Primary Capillary Plexus Secondary Capillary Plexus
Where do many nuerones (not all) coming from the hypothalmic nuclei terminate at?
Lots of neurones coming from the hypothalamic nuclei terminate on the walls of the PRIMARY CAPILLARY PLEXUS