small groups Flashcards
In a postmenopausal woman with low estradiol should the levels of LH and FSH be low or high?
High
The effects of radiotherapy on the pituitary can be delayed for years, name a common delayed effect on the pituitary as a result
panhypopituitarism
Which hormones are protein, steroid or tyrosine derivatives (biogenic amines)?
Steroid hormones- Thyroid hormones (T3,T4), cortisol, and androgens (estrogen, progesterone, testosterone)
Proteins: GH, LH, FSH, TSH, ACTH, prolactin, hCG, TRH, CRH
Tyrosine derivatives: Thyroid (steroid), Catecholamines (peptide)
Compare steroid hormones to peptide hormones
They must be bound in the blood and this creates a storage reserve and increases the half life of the hormones bound. Peptide hormones are soluble in blood and have shorter half lives, they can also be excreted more easily, whereas protein bound steroid hormones can’t be filtered in the kidneys due to size.
Steroids are also more stable at a low pH
They bind to cytoplasmic or nuclear receptors, and the number of these receptors determines the extent of the biological response. Whereas protein membrane receptors are in excess and the concentration of the hormone determines the maximal biologic response.
Whats the utility of the pulsatile release of GnRH?
GnRH is released every 60-90 mins and this stimulated gonadotrophs in the anterior pituitary to upregulate their receptors to receive the hormone; and thus release LH/FSH in a similar pulsatile maner. Continuous administration would downregulate these receptors.
Primary hypopituitarism can lead to what type of complications in the thyroid, adrenal gland, testies, breast?
secondary adrenal insufficiency, secondary hypothyroidism (secondary to the pituitaries decreased secretion of trophic hormones)
decrease breast milk production, lack of prolactin
hypogonadism from decreased LH, and FSH
Cancers can cause hypersecretion of hormones or deficiency; why both?
Hypersecretion occurs when the endocrine cells themselves become cancerous; somatotroph for example.
Hyposecretion occurs when the cancer invades non hormone producing cells within the gland which can then either: destroy, injure, or diminish function, of hormone producing cells; craniopharyngiomas, sheehans(postpartum pituitary necrosis), pancreatitis (Type 1 DM)
