BIO Ch. 5 Endocrine System Flashcards
How do peptide hormones operate?
peptide hormones bind to membrane-bound receptors to initiate a signaling cascade, using second messengers like cyclic adenosine monophosphate (cAMP), inositol triphosphate (IP3), and calcium
What is the diff b/w peptide and steroid hormones?
peptide hormones are made up of amino acids derived from polypeptides, water-soluble, short-lived, charged, and travel through the bloodstream.
steroid hormones are derived from cholesterol produced by gonads and adrenal cortex, nonpolar, and can easily cross the cell membrane
How do steroid hormones work?
they bind to intracellular receptors in the cytosol or nucleus and function by binding to DNA to alter gene expression altering the amount of mRNA and protein present in a cell
How are steroid hormones activated?
while attached to carrier proteins, steroid hormones are inactive and must disassociate to carry out function, thus the levels of carrier proteins change the level of active hormones
What are some examples of amino-acid-derived hormones?
epinephrine, norepinephrine, triiodothyronine, thyroxine
What are some examples of peptide-derived hormones?
insulin, vasopressin, thyroxine, triidyronine
What are some examples of steroid-derived hormones?
testosterone, estrogen, cortisol, glucocorticoids, cholesterol
What is the diff b/w the activation of catecholamines and thyroid hormones?
catecholamines (norepinephrine and epinephrine) bind to G-protein-couple receptors while thyroid hormones bind intracellularly
How does the hypothalamus regulate?
via negative feedback which occurs when a hormone later in the pathway inhibits its hormones earlier in the pathway
What is the diff b/w direct and tropic hormones?
direct hormones are secret directly on the target tissues such as insulin secreted by the pancreas causing the increase of uptake of glucose by muscles
tropic hormones require an intermediary to act such as gonadotropin-releasing hormone (GnRH) from the hypothalamus to stimulate the release of LH and FSH which can then act to stimulate testosterone and estrogen
Where does the hypothalamus secrete its products?
it secretes compounds into the hypophyseal portal system (blood vessel system that directly connects the hypothalamus to the anterior pituitary) that travel down the pituitary stalk to bind to receptors on the anterior pituitary
Which hormones are released by the pituitary when GnRH hormone is secreted by the hypothalamus?
FSH and LH
Which hormones are released by the pituitary when GHRH hormone is secreted by the hypothalamus?
Growth hormone
Which hormones are released by the pituitary when TRH hormone is secreted by the hypothalamus?
TSH
Which hormones are released by the pituitary when CRF hormone is secreted by the hypothalamus?
ACTH
Which 2 hormones are received by the posterior pituitary?
oxytocin and antidiuretic hormone (ADH) are synthesized by the thpothalmus and reasles in the posterior pituitary
What is the exception hormone of the hypothalamus?
prolactin-inhibiting factor (PIF), which is actually dopamine, is released by the hypothalamus and causes a decrease in prolactin secretion
What is the role of oxytocin?
stimulation contractions of uterine smooth muscles during labor through a positive feedback mechanism, and milk letdown during lactation
What is the role of ADH?
Increase of water reabsorption in the collecting ducts of the nephrons in the kidneys in response to increased plasma osmolarity or increased concentration of solutes within the blood
What Are the 4 tropic hormones released by the anterior pituitary gland?
FSH, LH, ACTH, TSH
What Are the 4 Direct hormones released by the anterior pituitary gland?
prolactin, endorphins, and GH
What is the role of growth hormone?
promotes the growth of bone and muscle, prevents glucose uptake in certain tissues (those not growing), and stimulates the breakdown of FA
What is the role of prolactin?
stimulation of milk production in the mammary glands
What is the diff b/w gigantism, dwarfism, and acromegaly?
bone growth originates in the epiphyseal plates which seals during puberty. An excess of GH release in childhood before the closure of the plates can cause gigantism and a deficit results in dwarfism. Acromegaly affects the smaller bones like the hands, feet, and head
