Pituitary gland Flashcards
What is a hormone and how are they transported?
A messenger that is carried from the organ where they are produced to the organ which they affect through the blood stream
How are peptide hormones synthesised?
Synthesised as prohormones requiring further processing (e.g. cleavage) to activate
Where are peptide hormones stored?
Stored in vesicles and then released in response to a stimulus (regulatory secretion)
What receptors do peptide hormones bind to?
Bind receptors on cell membrane and transduce signal using 2nd messenger systems
How are steroid hormones synthesised?
Synthesised in a series of reactions from cholesterol
Where are steroid hormones stored?
They’re not- they’re released immediately (constitutive secretion)
What receptors do steroid hormones bind to?
Bind to intracellular receptors to change gene expression directly
What do hypothalamic parvocellular neurons regulate?
The function of the anterior pituitary
Are hypothalamic parvocellular neurons long or short?
Short
Where do hypothalamic parvocellular neurons terminate?
Median eminence
What factors do hypothalamic parvocellular neurons release and where?
hypothalamic releasing/inhibitory factors (hypothalamic regulatory factors) into capillary plexus in median eminence
What are hypothalamic regulatory factors carried by and where to?
By portal circulation to anterior pituitary
What endocrine cells are in the anterior pituitary?
Somatotrophs
Lactotrophs
Corticotrophs
Thyrotrophs
Gonadotrophs
What is the anterior pituitary regulated by?
hypothalamic releasing/inhibiting factors via hypothalamic-pituitary portal system
Describe the process of the hypothalamic-pituitary portal system
- Axon terminals of hypothalamic neurosecretory cells release hormones (RHs and IHs) into the
hypothalamo-pituitary portal system - The RHs and IHs travel in the portal system to the anterior pituitary
- The RHs and IHs stimulate or inhibit the release of hormones (black dots) from anterior pituitary cells
- Anterior pituitary hormones leave the gland via the blood
What hormone do somatotrophs release?
Growth Hormone (GH)
What hormone do lactotrophs release?
Prolactin