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PHGY 210-ENDO Exam With Complete Solution
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PHGY 210-ENDO Exam With CompleteSolution
what is paracrine signalling? - Answer local signalling of a cell with a target cell
what is autocrine signalling? - Answer cell talking to itself
what are the 6 steps of communication by hormones? - Answer 1) synthesis of the
hormone by the endocrine cells
2) release of the hormone by the endocrine cells
3) transport of the hormone to the target site by the blood stream
4) detection of the hormone by a specific receptor protein on target cells
5) change in cellular metabolism triggered by the hormone-receptor interactions
6) removal of the hormone, which often terminates the cellular response
what are the 2 ways that the hypothalamus is connected to the pituitar? - Answer 1-
through the hypothalamic-hypophyseal portal system-from hypothalamus to ant.
pituitary
2-to post. pituitary
what do hypothalamic neurotransmitters do? - Answer either activate or inhibit activity
of one of the 6 types of hormone-producing cells in the ant. pituitary
-releasing hormones
-inhibiting hormones
what are the classes of hormones? - Answer -glycoproteins
-polypeptides
-steroids
-amines
-ionic calcium (has a calcium sensing receptor so its a hormone)
for which classes of hormones do we have a gene in our genome to build it? - Answer
-glycoproteins
-polypeptides
how do we make amines and steroids? - Answer we do not have a gene in our genome,
,however we have genes that encode enzymes that are necessary for the biosynthesis of
the hormones
describe the synthesis of protein hormones - Answer protein that is encoded by the
gene has end terminal extensions on it called prepro sequences that act as bar codes
that direct proteins into the secretory system.
Synthesis begins on ribosomes of preprohormones, then travel to ER where
preprohormones are converted to prohormones then travel to golgi apparatus where
prohormone is packaged into secretory vesicles that leave the cell and release the
hormone and other peptides
how many rings do steroids have? - Answer 4
what are the thyroid hormones? - Answer T3 and T4
why is reverse T3 not a thyroid hormone? - Answer cannot bind to thyroid receptors
(due to singular iodine on proximal ring)
what percent of T3, T4 and rT3 do we have? - Answer T4: 90%
T3: 9%
rT3: 0.9%
what do the numbers signify on the thyroid hormones? - Answer how many iodines they
have
what is the type of mechanism called for a hypothetical membrane receptor? - Answer
lock and key
what are the properties of hormone receptors? - Answer -specificity: recognition of a
single hormone
-affinity: binding hormone at its physiological conc.
-should show saturability: a finite number of receptors
-measureable biological effect: biological response due to interaction of hormone with
its receptor
how can receptors be upregulated? - Answer -increasing synthesis
-increasing their activity in response to hormone
what are the 3 mechanisms by which a hormone can exert effects on target cells? -
Answer -direct effects on function at the cell membrane
-intracellular effects mediated by second messenger systems
-intracellular effects mediated by genomic or nuclear action
, give an example of direct effects on function - Answer insulin binds to insulin receptor in
membrane, which can send signal indirectly in nucleus leading to changes in gene
transcription. Insulin is essential for stimulating cells to take up glucose. Then glucose
can enter with a glucose carrier.
which type of receptor is involved in intracellular genomic signalling - Answer nuclear
receptors (including receptors for steroid hormones)
describe intracellular genomic signalling - Answer steroid hormone can enter directly,
binds to a specific hormone receptor in the cytoplasm which travels into the nucleus
where it regulates transcription of certain genes, changing proteins and thus changing
the way the cell functions
describe the feedback control of hormone secretion - Answer -hormone secretion is
regulated by feeback mechanisms
-an excess of hormone, or excess hormonal activity, leads to a diminution of hormone
secretion
-a deficiency of hormone leads to an increase in hormone secretion
what are the ant. and post. pituitary also called? - Answer ant. : adenohypophysis
post.: neurohypophysis
what are the ant. and post. pituitary made of? - Answer ant.: endocrine tissue
post.: neural tissue (extension of hypothalamus)
name post. pituitary hormones - Answer -arginine vasopressin
-oxytocin
name hypophyseotropic hormones - Answer -TRH (thyrotropin-releasing)
-GnRH (gonadotropin releasing)
-somatostatin
-GRH (growth hormone releasing)
-PIH, dopamine (prolactin inhibiting)
-CRH (corticotropin releasing)
what do hypophyseotropic hormones target? - Answer ant. pituitary gland
where is oxytocin synthesized? - Answer paraventricular nucleus
where is vasopressin synthesized? - Answer supraoptic nucleus
where do oxytocin and vasopressin axons terminate? - Answer post. pituitary near
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