A&P: Pituitary Hormones Flashcards
Oxytocin
Peptide
Posterior pituitary
Mostly from neurons in paraventricular nucleus of hypo.
PIP2-Ca++ signaling pathway
Stimulated by: impulses from hypothalamic neurons; response to cervical/uterine stretching and suckling
Inhibited by: lack of appropriate stimuli
Uterus: stimulates uterine contractions; initiates labor
Breast: milk ejection = “letdown reflex”
Antidiuretic hormone (ADH) or vasopressin
Peptide
Posterior pituitary
Mostly from neurons in supraoptic nucleus of hypo.
cAMP signaling pathway
Stimulated by: impulses from hypothalamic neurons; response to increased blood solute concentration or decreased blood volume
-Pain, some drugs, low BP
Inhibited by: adequate hydration of body + alcohol
Kidneys: stimulate kidney tubule cells to reabsorb water
Inhibits urine formation + vasoconstricts
Growth hormone (GH)
Protein
Anterior pituitary
Somatotropic cells
Stimulated by: GHRH release (triggered by low blood levels of GH as well as hypoglycemia, increases in blood levels of amino acids, low levels of fatty acids, exercise, and other stressors)
Inhibited by: feedback inhibition exerted by GH and IGFs and by hyperglycemia, hyperlipidemia, obesity, emotional deprivation via either increased GHIH or decreased GHRH release)
Liver, muscle, bone, cartilage, etc.: anabolic hormone; stimulates somatic growth; mobilizes fats; conserves glucose
“Anti-insulin effect”
Growth-promiting effects mediated indirectly by IGFs
Thyroid-stimulating hormone (TSH)
Glycoprotein
Anterior pituitary
Thyrotropic cells
Stimulated by: TRH and in infants indirectly by cold temp
Inhibited by: rising blood levels (feedback inhibition) thyroid hormones on anterior pituitary & hypothalamus and by GHIH
Thyroid gland: stimulates thyroid gland to release thyroid hormones
Adrenocorticotropic hormone (ACTH)
Peptide
Anterior pituitary
Corticotropic cell
Stimulated by: CRH (Stimuli that increased CRH release include fever, hypoglycemia, and other stressors)
Inhibited by: feedback inhibition by glucocorticoids
Adrenal cortex: promotes release of glucocorticoids and androgens
Follicle-stimulating hormone (FSH)
Glycoprotein
Anterior pituitary
Gonadotropic cells
Stimulated by: GnRH
Inhibited by: feedback inhibition exerted by inhibin and estrogen in females (testosterone in males)
Ovaries and testes: stimulates ovarian follicle maturation and estrogen production; stimulates sperm production
Luteinizing hormone (LH)
Glycoprotein
Anterior Pituitary
Gonadotropic cells
Stimulated by: GnRH
Inhibited by: feedback inhibition by estrogen and progesterone in females and testosterone in males
Ovaries and testes: ovulation and stimulates ovarian production of estrogen and progesterone; in males promotes testosterone production
Prolactin (PRL)
Protein
Anterior pituitary
Prolactin cells
Stimulated by: decreased PIH; release enhanced by estrogens, birth control pills, breast-feeding and dopamine-blocking drugs
Inhibited by: PIH (dopamine)
Breast secretory tissue: promotes lactation
