Endo - Physiology (Hypothalamus & Pituitary) Flashcards
Pg. 309-311 in First Aid 2014 or Pg. 289-290 in First Aid 2013 Sections include: -Hypothalamic-Pituitary hormones [regulation in FA 2013] -Prolactin -Growth hormone (somatotropin) -[Antiduretic hormone in FA 2014]
In hypothalamic-pituitary hormone regulation, what role does TRH play?
Hypothalamic TRH = Thyrotropin-releasing hormone stimulates TSH & prolactin release from anterior pituitary
In hypothalamic-pituitary hormone regulation, what role does Dopamine play?
Hypothalamic Dopamine inhibits prolactin release from anterior pituitary
In hypothalamic-pituitary hormone regulation, what role does CRH play?
Hypothalamic CRH = Corticotropin-releasing hormone stimulates ACTH and melanocyte-stimulating release from anterior pituitary as well as beta-endorphin release
In hypothalamic-pituitary hormone regulation, what role does GHRH play?
Hypothalamic GHRH = Growth hormone-releasing hormone stimulates GH release from anterior pituitary
In hypothalamic-pituitary hormone regulation, what role does Somatostatin play?
Hypothalamic Somatostatin inhibits release of GH & TSH from anterior pituitary
In hypothalamic-pituitary hormone regulation, what role does GnRH play?
Hypothalamic GnRH = Gonadotropin-releasing hormone stimulates release of FSH & LH from anterior pituitary
In hypothalamic-pituitary hormone regulation, what role does Prolactin play?
Prolactin release from the anterior pituitary inhibits GnRH release from the hypothalamus
What is the source of Prolactin?
Secreted mainly by anterior pituitary
What is the function of Prolactin?
(1) Stimulates milk production in breast (2) Inhibits ovulation in females and spermatogenesis in males by inhibiting GnRH synthesis and release
What inhibits Prolactin, and what is the source of this factor? What is the feedback in place with regard to this process?
Dopamine from Hypothalamus; Prolactin in turn inhibits its own secretion by increasing dopamine synthesis and secretion from hypothalamus
What stimulates Prolactin, and what is the source of this factor?
TRH from Hypothalamus
What can be used in the treatment of prolactinoma, and why?
Dopamine agonists (e.g., bromocriptine) inhibit prolactin secretion
What kinds of drugs stimulate prolactin secretion?
(1) Dopamine antagonists (most antipsychotics (2) Estrogens (OCPs, pregnancy)
Draw the pathways of Prolactin that relate to the following: (1) Anterior Pituitary (2) Hypothalamus (3) Dopamine (4) TRH (5) Milk Production (6) GnRH (7) Spermatogenesis (8) Ovulation.
See First Aid p. 290
What is another name for growth hormone? What is its source?
Somatotropin; Secreted mainly by anterior pituitary
What is the major function of growth hormone (somatotropin)? What is an associated deleterious effect of GH?
Stimulates linear growth and muscle mass through IGF-1/somatomedin secretion; Increases insulin resistance (diabetogenic)
What increases secretion of GH?
(1) Released in pulses in response to GHRH (2) Secretion increased during exercise and sleep
What inhibits secretion of GH?
Secretion inhibited by glucose and somatostatin
What is an example of a disease/condition that would cause excess secretion of GH? What can occur as a result of excess secretion of GH?
Pituitary adenoma; (1) Acromegaly (adults) (2) Gigantism (children)
What is a clinical context in which CRH is decreased?
Decreased in chronic exogenous steroid use
In what clinical context are dopamine antagonists used? What symptom can they cause, and why?
Dopamine antagonists (e.g. antipyschotics) can cause galactorrhea; Dopamine normally functions to decrease prolactin (i.e., increased prolactin due to dopamine antagonists causes galactorrhea)
What regulates GnRH, and how so?
Regulated by prolactin; Prolactin decreases GnRH
What is the outcome of tonic versus pulsatile GnRH?
Tonic GnRH suppresses HPA axis; Pulsatile GnRH leads to puberty, fertility
What are 2 symptoms/results of pituitary prolactinoma?
Pituitary prolactinoma –> amenorrhea, osteoporosis
What are somatostatin analogs used to treat, and why?
Analogs use to treat acromegaly; Somatostatin decreases GH
Where exactly is antidiuretic hormone synthesized? Where is it released?
Synthesized in hypothalamus (supraoptic nuclei), released by posterior pituitary
What are 2 major functions of antidiuretic hormone, and through which receptors does it accomplish these?
Regulates (1) serum osmolarity (V2-receptors) and (2) blood pressure (V1-receptors)
Again, what are the 2 major functions of antidiuretic hormone, and through which receptors does it accomplish these? Which of these is its primary function, and what is the mechanism behind this?
Regulates (1) serum osmolarity (V2-receptors) and (2) blood pressure (V1-receptors); Primary function is serum osmolarity regulation (ADH decreases serum osmolarity, increases urine osmolarity) via regulation of aquaporin channel transcription in principal cells of renal collecting duct
What are the primary versus secondary regulators of antidiuretic hormone?
Osmoreceptors in hypothalamus (primary); hypovolemia (secondary)
What is the ADH level in each of the following clinical contexts: (1) Central diabetes insipidus (DI) (2) Nephrogenic DC (3) Primary polydipsia.
ADH level is (1-2) decreased in central diabetes insipidus (DI) and primary polydipsia (3) normal or increased in nephrogenic DI
What mutation can cause nephrogenic DI?
Nephrogenic DI can be caused by mutation in V2 receptor
What is desmopressin, and for what condition is it used as a treatment?
Desmopressin (ADH analog) = treatment for central DI
