Endocrinology 3- Hypothalamus And Pituitary Relationship Flashcards
Where is the hypothalamus
At base of brain but above pituitary gland (which is outside of the brain)
What can we consider the hypothalamus as, as far as role?
An integration center - limbic system processes emotion and fear, sensory system, reticular activating system is part of brain stem, viscera takes in things coming from organs, hormones are in blood, and chemical substrates are all going to be integrated here and processed to have a correct response.
What are the 4 hypothalamic nuclei she wants us to know
PVN (blood pressure)
SO (Thirst)
ARC ( feeding behavior, satiety)
POA (Body temperature)
Can pituitary release hormones without hypothalamus
Hypothalamus is absolutely required for pituitary function
What is the area where hypothalamus axons converge toward where they will dump hormone into the pituitary portal system
median eminance
What is kallan syndrome
GnRH hormones fail to enter CNS –> Reproductive failure and asomnia (no smell) – x linked
neurons get stuck in cribriform plate
Why is pulsitility of hormone release important?
So that you aren’t just downregulating the receptors on target organs – you need to release in a manner so that those receptors are replaced
A hypothalamic hormone binding to the anterior pituitary gland will lead to what two outcomes
Release and synthesis of hormoen
What is the hypophysial portal system
Vascular connection between hypothalamus and pituitary gland
How was the hypophysial portal system discovered
When the pituitary gland was transplanted to other regions of the body it didn’t work, but when it was reimplanted beneath hypothalamus it worked
Do the anterior and posterior pituitary have the same blood supply
NO
Does the posterior pituitary have a portal system
NO
Tuberoinfundibular system
Tract of neurons that goes to anterior pituitary - project to median eminance, deposit hormones into portal system
Neurohypophysial tract
Neurons whose axons terminate in posterior pituitary
3 regions of anterior pituitary gland
pars distalis, pars tuberalis, pars intermedia
2 regions of posterior pituitary
Pars nervosa, infundibulum (stalk)
Pars tuberalis - what is here?
Median eminance
What is the big bulb of the anterior pituitary called
Pars tuberalis
What are the “hypophysis” names for anterior and posterior pituitary gland?
Adenohypophysis: Anterior pituitary
Neurohypophysis: Posterior pituitary
What kind of tissue makes up the adenohypophysis (anterior pituitary)
Glandular tissue, cords of epithelial cells
What kind of tissue makes up neurohypophysis/posterior pituiary
Neural tissue - terminal axons and glial cells
Major hormones frm posterior pituitary gland
Arginine vasopressin/antidiuretic hormone (AVP/ADH) and oxytocin (OXY)
Cell bodies from the posterior pituitary are where? What is the name for their cell type?
Hypothalamus - mangocellular
What is the lobe of the pituitary that is basically just termination from long axons from the hypothalamus
posterior pituitary gland
Axons for cell bodies in posterior pituitary gland terminate where? What is this location called?
Near fenestrated capillaries - into structures called herring boddies
What exactly are herring bodies
dilations of unmyelinated axons near their terminals containing either AVP or OXY + a binding protein, neurophysin
What is the median eminance?
The interface for all hypophysiotrohic hormones - it lies outside of the blood brain barrier. This is where axons will converge from hypothalamus for the anterior pituitary gland
Is the median eminance inside or ouside the blood brain barier
outside
5 cell types in anterior pituitary which are activated by portal system
Lactotrophs (make prolactin) somatotrophs (make growth hormone) thyrotrophs (tsh) gonadotropes (lh/fsh) corticotropin
Acidophils
Most abundant of hormone producing cells, include somatotrophs and lactotrophs
Basophils
Corticotrophs, gonadotrophs, and thyrotrophs
Chromophobes
Paracrine cells
Where are GH and PRL releasing cells primarily located
On the outside parts of the pituitary
Where are ACTH releasing cells located
On the inner part of the anterior pituitary (middle)
Where are TSH releasing cells primarily located
At the most far part of the pituitary from the neurohypophysis in the middle
Where are FSH and Lh released from in anteiror pituitary
everywhere sprinkled around
Do pituitary hormones have a circadian rhythm
Yes
