168. Hypothalamic-Pituitary Basic Physiology Flashcards
Confers the biologic specificity of hormones
beta-subunit
Essential for boney growth and has effects on fat, muscle, and CHO GHRH (+) and somatostatin (-)
Growth hormone
High estrogen levels of pregnancy result in hyperplasia of lactotrophs and high ___ levels
Prolactin
Stimulates gonadal steroid production
Midcycle surge triggers ovulation (release of egg) GnRH (+)
LH
Derive from an evagination of neural ectoderm of the ventral diencephalon
Posterior lobe of pituitary
Stimulates mild let-down and postpartum uterine contraction
Stimulated by suckling
Oxytocin
Mutations in these peptides give rise to combined pituitary hormone deficiency through lack of development of certain pituitary cells but hypothalamic structures are normal
Pit-1 and PROP-1
Stimulates follicle and sperm development GnRH (+)
FSH
Under tonic inhibition by the hypothalamus via dopamine
Cutting of the stalk causes hypopituitarism but also an increase in this hormone
Prolactin
Secreted by the somatotrophs (50% of pituitary cells)
Promotions of linear growth at the growth plates of bones
Increases osteoclast differentiation and activity
Increases osteoblast activity
Increases bone mass by endochondral bone formation
Growth hormone
Converts electrical signals from the retina into hormonal signals
Pineal gland
Need ___ secretion instead of continuous for adequate hormone release
Pulsatile
Localized in hypothalamic nuclei that project to the median eminence to secrete peptide and bioamine releasing and inhibiting hormones into the proximal end of the hypothalamic-pituitary portal vessels
Hypophysiotropic neurons
Made by Liver and bones after Growth Hormone has acted on them
- most comes from liver
Then acts in a negative feedback loop on the pituitary and hypothalamus
IGF-1
Primary regulator of ADH secretion
Senses hyperosmolality (hypernatremia) which stimulates ADH release
Senses hypoosmolality (hyponatremia) which suppresses ADH release
Osmoreceptors in hypothalamus
Produced by corticotrophs (10-20% of pituitary cells)
Derived from POMC
Main product in pituitary
Stimulates adrenal cortex to produce cortisol and adrenal androgens
Little effect on aldosterone
Stimulated by CRH Stress mediated
ACTH