Neuroendocrinology Flashcards
What are neuroendocrine cells?
They are neurosecretory cells that release signal molecules (hormones) from their synaptic terminals into the blood. It is controlled via synaptic transmission from presynaptic neurons (neuroendocrine integration)
Outline the embryology of the pituitary gland
Evagination of the floor of 3rd ventricle (neural ectoderm)
Evagination of oral ectoderm (Rathke’s pouch)
Rathke’s pouch pinched off
What are parvocellular nuclei?
They are neurosecretory cells that release hormones to the capillaries of median eminence (supplied by superior hypophysial artery); conveyed by portal veins to the anterior pituitary where the capillaries revascularize into the capillary bed
How do hormones and blood leave the anterior lobe of the pituitary gland?
The hypophyseal portal vein
What are magnocellular nuclei?
They are neurosecretory cells that project their axons straight to the posterior pituitary and release into capillaries supplied by the inferior hypophyseal artery
How do hormones and blood leave the posterior lobe of the pituitary gland?
The inferior hypophyseal vein
What hormones are released by the posterior lobe?
Oxytocin and ADH
How do growth hormones affect tissues?
Either directly or through the liver which produces IGF-1
GH functions?
Growth and development (anabolic)
Couples growth to nutritional status
What is excess GH called?
Acromegaly - Most commonly due to pituitary adenoma: increase in GH-secreting somatotropes
Less commonly secondary: a tumour elsewhere secretes GHRH
What does acromegaly cause?
Excess GH leads to insulin resistance
Many patients will have impaired glucose tolerance and hyperinsulinemia
What will increase an in glucose levels do to GH levels in normal human being?
Sharp drop in GH levels
