need help understanding pituitary?

[axeon123]

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I'm trying to figure out the anterior/posterior pituitary. Posterior pituitary - you get hormones synthesized from supraoptic for ADH and paraventric for oxytocin; these get stored at nerve terminals and then stimulation makes it get released.

But anterior pituitary, I'm not sure how this works. I know there is a portal network where the hypothalamus makes hormones that then stimulate hormone (is that the right word?) release from AP. So the hypothalamus hormones travel down the neurohypophysis and this stimulates the AP neurons. But, are the AP hormones presynthesized (eg AP has a separate set of neurons that is stimulated by hypothalamic neurons, and is TSH/GH/etc already stored in the AP neurons just waiting to be released? Thanks.

 

[username456789]

Ther are specific cells in the AP that make the AP hormones. They do so in response to hypothalamic trophic hormones. An example is corticotrph cells that make ACTH in response to CRH that comes from the hypothalamus down through the venous plexus.

The AP doesn't use neurons for storage/synth/release of its hormones like the PP does.

 

[pseudorosette]

I'm trying to figure out the anterior/posterior pituitary. Posterior pituitary - you get hormones synthesized from supraoptic for ADH and paraventric for oxytocin; these get stored at nerve terminals and then stimulation makes it get released.

But anterior pituitary, I'm not sure how this works. I know there is a portal network where the hypothalamus makes hormones that then stimulate hormone (is that the right word?) release from AP. So the hypothalamus hormones travel down the neurohypophysis and this stimulates the AP neurons. But, are the AP hormones presynthesized (eg AP has a separate set of neurons that is stimulated by hypothalamic neurons, and is TSH/GH/etc already stored in the AP neurons just waiting to be released? Thanks.

The cells in the AP are glandular, not neuronal. I guess that's why they call it the adenohypophysis. Remember, they're ectodermal derivatives of Rathke's pouch (which craniopharyngiomas can arise from). They just release their stores of AP hormone when stimulated by the hypothalamic hormone that they have a receptor for, which like you said gets there through the hypophyseal portal system.

I just remember B-FLAT for anterior pituitary cells: the Basophils make FSH, LH, ACTH and TSH. The acidophils make the rest of hormones (GH and prolactin). Then are also chromophobes in the anterior pituitary which look like floating nuclei with no cytoplasm... I was told that these are probably just basophils or acidophils that have released their hormonal contents.

Yeah it kinda sucks that "basophils" could refer to an AP cell or a WBC... 😛