Intro Flashcards
what tissues secrete hormones that are not traditional endocrine orans?
GI tract and kidneys
what hormone is secreted by the placenta? what does it do?
chorionic gonadotrophin-stimulates the corpus luteum to produce estrogen and progesterone in early pregnancy
human placental lactogen- stimulates lactation
estrogens and progesterone
what classes of hormones are there? what kinds of receptors do they activate
polypeptides, amines or steroids (-sterone or -ol ending)
peptides and amines- cell surface receptors
steroid hormones- nuclear or cytoplasmic receptors
what are neuroendocrine hormones?
released by neurons into the blood
describe the storage and action of peptide hormones. how does this differ from steroids?
stored in secretory vesicles and activate second messengers
steroid hormones produced on demand and control gene transcription
describe pseudohypoparathyroidism.
PTH is secreted but there is a problem with the receptor’s g protein-cannot mediate its effects
how is the pituitary regulated?
by vascular signaling in the adenohypophysis
axons of hypothalamus releases hormones into the hypophyseal portal circulation
neuronal control in the neurohypophysis by the hypothalamus
what types of blood does the anterior and posterior pituitary receive?
anterior- venous
posterior- arterial
describe the function of the posterior pituitary
axons from the hypothalamic nuclei extend to the posterior pituitary where it stores the hormones in nerve terminals. released when needed
what hormones are secreted by the posterior pituitary?
ADH and oxytocin (smaller peptides)
which anterior pituitary hormone is not controlled by hypothalamic releasing factors?
prolactin
which anterior pituitary hormone has inhibitory control?
growth hormone is inhibited by somatostatin
what are the six major hormones of the anterior pituitary?
LH, FSH, TSH, ACTH, prolactin and growth hormone
what is long loop feedback?
feedback of hormones released from peripheral glands onto the HPA
what is short loop feedback?
anterior pituitary hormones feeding back on the hypothalamus
what does prolactin do?
stimulates milk production during lactation, promotes breast development in puberty and pregnancy and inhibits ovulation
what is the normal inhibition of prolactin caused by? how is excessive prolactin secretion treated?
dopamine tonically inhibits prolactin synthesis
treated with dopamine receptor agonist
what do neurophysins do?
transport ADH (2) and oxytocin (1) from the hypothalamic nuclei to the posterior pituitary
what does oxytocin do?
stimulates milk let down from breast with suckling and uterine contractions in response to cervical dilation
what other factors cause oxytocin release?
orgasm and sight, smell or sound of an infant
what nucleus synthesizes oxytocin and ADH?
the paraventricular nucleus
what does ADH do?
released in response to increased osmolarity and decreased blood pressure- promotes water resorption in the kidney (V2 receptor) and venous contraction (V1 receptor)
what is central diabetes insipidus?
failure of the posterior pituitary to secrete ADH
what two circumstances could cause hypopituitarism?
insufficiency of hypothalamic releasing hormones or inability of pituitary to produce hormones (tumor most common cause)
