lecture 3 endocrine Flashcards
(24 cards)
what are the major components of the endocrine system?
Hypophysis(pituitary), pineal gland, parathyroid glands, thyroid gland, thymus gland, adrenal glands, pancreas, ovaries, testes, placenta
what is the master gland?
pituitary gland
estrogen and testosterone are what type of hormone?
steroid hormone
oxytocin and adh are what type of hormones?
non-steroid hormones
what is the mechanism of action of a peptide hormone?
ligand binds to cell surface receptor. Signal is transduced to the cell interior, where it modifies the activity of cytoplasmic enzymes.
what is the mechanism of action of a steroid hormone?
lipid-soluble steroids enter the cell cytoplasm by diffusion and bind to receptors in the cytoplasm or nucleus. the steroid/receptor complex binds to regulatory regions of DNA, affecting expression of specific steroid responsive genes
describe path of hormones secreted from the posterior pituitary
- neurosecretory cells produce ADH and oxytocin
- these hormones move down axons to axon endings and synapse onto posterior pituitary
- when appropriate, ADH and oxytocin are secreted from axon endings in the posterior pituitary into the blood stream
describe path of hormones secreted from anterior pituitary
- neurosecretory cells produce releasing and release-inhibiting horomnes
- these hormones are secreted into portal system
each hypothalamic hormone either stimulates or inhibits production and secretion of an anterior pituitary hormone
the anterior pituitary secretes its hormones into the blood stream
what hormones are secreted from the posterior pituitary?
ADH (kindey), oxytocin (smooth muscles in uterus, mammary glands)
what hormones are secreted from the anterior pituitary
TSH (thyroid), adrenocorticotropin (ATCH) (adrenal cortex), prolactin (mammary glands), growth hormone (bones, tissues), FSH, LH (ovaries and testes)
How does oxytocin lead to milk let down?
- nursing stimulates nerve receptors in nipple
- sensory nerves carry impulses to the neuroendocrine cells of hypothalamus
- neuroendocrine cells relase oxytocin when stimulated
- oxytocin is transported by blood to mammary glands
what hypothalamic hormone stimulates prolactin? what hormone inhibits prolactin?
PRF (prolactin releasing factor) activates prolactin (prh)
PIH (prolactin inhibiting hormone) inhibits prolactin (prh)
what hypothalmic hormone affects LH and FSH release?
GnRH (gonadotropin releasing hormone)
what happens ia GnRH stimulatory agonist administrated in a pulsatile manner?
in crease in FSH/LH = gain in fertility
what happens ia GnRH inhibitory antagonist administrated in a constant manner?
decrease in FSH/LH = loss of fertility
what happens ia GnRH antagonist is administrated?
decrease in FSH/LH = loss of fertility
what is kallmann’s syndrom?
Kallman’s syndrom causes human infertility and anosmia (the inability to smell). This is because olfactory nerves carry nerual information from the olfactory lining in the nasal cavity to the base of the cerebral hemispheres in the brain. For people in kallman’s syndrom this is defective.
how is estradiol regulated in females?
in response to GnRH the pituitary releases LH which is transported to the ovaries. estradiol, secreted by the ovaries, feeds back on GnRH. Because GnRH neurons lack estrogen receptors, both positive and negative feedback is thought to be mediated by other neurons in the hypothalamus. for example Kispeptin-secreting neurons are response to estradiol, synapse with GnRH neurons, and release kisspeptins that stimulate GnRH neuron activity.
what are steroid hormones?
cholesterol based structure lipophliic- can pass through membrane acts as transcription factors often binds to carrier proteins in blood can bind to classes of similar hormones \: testosterone R. can bind to DHT, testosterone, and other androgens. Estrogen R can bind to estriole, estrone, estradiol, and other estrogens
what are nonsteroid hormones?
amino acid subunit structure lipophobic, binds to membrane receptors amplifies signals through cascade events highly specific acts quickly through apmplifed singal
what converts testosterone to DHT?
5 alpha reductase
what converts testosterone into estradiol?
aromatase
what inhibits FSH relase from A.P.
inhibin
what is involved in coiling of siminferous tubules in embryonic testes?
activin
