Intro to HPEO Axis Flashcards
HPEO axis involves what 3 parts of the body
Hypothalamus
Anterior pituitary
One of the end organs (thyroid, adrenal cortex, gonads, liver)
Sella turcica
“Turk’s saddle” of the sphenoid bone
Just below the hypothalamus
Encloses the pituitary gland
Infundibulum
Connecting stalk that attaches the pituitary to the hypothalamus
Adenohypophysis
what part of the pituitary, where does it develop from, what does it do
Anterior pituitary
Develops from oral ectoderm (Rathke’s pouch)
Composed of glandular tissue that produces and releases 6 major hormones
Neurohypophysis
what part of the pituitary, where does it develop from, what does it do
Posterior pituitary
Develops from neural ectoderm
Maintains neural connection to the brain
Site of storage and release of ADH and oxytocin (both are made by the hypothalamus)
3 parts of the vascular connection between the hypothalamus and anterior pituitary
Primary capillary plexus (in inferior hypothalamus)
Secondary capillary plexus (in anterior pit)
Hypophyseal portal veins (connect the 2 plexuses)
Collectively referred to as the hypothalamic-hypophyseal portal system
6 hormones of the anterior pituitary
Growth hormone (or somatotropin) Thyroid stimulating hormone Adrenocorticotropic hormone Follicle stimulating hormone Luteinizing hormone Prolactin
What hypothalamic hormones regulate each of the anterior pituitary hormones?
GH: + GH-releasing hormone, - somatostatin
TSH: + Thyrotropin-releasing hormone, - somatostain
ACTH: + Corticotropin-releasing hormone
FSH and LH: + Gonadotropin-releasing hormone
PRL: + PRL-releasing hromone, - dopamine
Dopamine negatively inhibits what anterior pituitary hormone?
Prolactin
What cell type makes
- GH
- TSH
- FSH and LH
- ACTH
- PRL
- Somatotrophs
- Thyrotrophs
- Gonadotropins
- Corticotrophs
- Lactotrophs
Growth hormone
Made by somatotrophs of the anterior pituitary
GH has direct actions on the liver (stimulates gluconeogenesis, increases lipolysis, and increases amino acid uptake and protein synthesis)
Indirectly related to growth - mediated by increasing the synthesis of insulin-like growth factors by liver (and bone and cartilage)
How can GH lead to T2D?
Chronic over secretion of GH leads to glucose intolerance and insulin resistance
Causes T2D
Thyroid-stimulating hormone
Produced by thyrotrophs
Stimulates the thyroid to make T4 (main) and T3
Adrenocorticotropic hormone
Produced by corticotrophs
Stimulates the cortex of the adrenal gland to produce glucocorticoid hormones, especially cortisol
Prolactin
Produced by lactotrophs
Main function is to stimulate breast development and lactogenesis
