hormonal control of metabolism II Flashcards
why is hormonal control of metabolism needed?
needed to keep fuel intake and energy expenditure in balance so an appropriate amount of adipose tissue in maintained
what happens when hormonal signals that control metabolism fail + you eat/drink more calories than you need? (2)
you convert the excess fuel into TAGs and store them in adipocytes, and you divert the excess fuel to heat production
which class of hormones are released from adipose tissue
adipokines
what type of hormones are adipokines
peptide hormones
role of adipokines?
they inform other tissues of the adequacy of TAG energy reserved to balance fat synthesis and oxidation
what was the first adipokine discovered
leptin
where in the body is leptin located
adipose tissue (bc it’s an adipokine)
when is leptin secreted from adipose
when TAG stores are sufficient to curtail appetite and increase energy expenditure (you have enough TAGs = stop eating)
list 3 things that may occur in the leptin knockout method (this was done in mice experiments)
high cortisol, unrestrained appetite, can’t stay warm
where does leptin secreted from adipocytes go
goes into the blood and to the hypothalamus
what happens when leptin reaches the hypothalamus
hypothalamus has leptin receptors, and it activates a neuronal response that returns back to adipocytes
after leptin binds to the hypothalamus and it sends it’s signal back to adipocytes, which neurotransmitter do the adipocytes release
norepinephrine
what happens once adipocytes secrete norepinephrine
norepinephrine activates a GPCR pathway to adenylyl cyclase, which increases cAMP levels and activates PKA
after norepinephrine release has led to PKA activation, what does PKA do (2)
activates mobilization of lipid droplets + activates the expression of the uncoupling protein (UCP1) in brown adipose tissue
expression of which uncoupling protein is activated by PKA
UCP1
where is UCP1 activated
brown adipose tissue
purpose of BAT
common in newborns/hibernating animals to keep vital organs warm
T or F: there is much less BAT in adults
true
how can BAT synthesis be activated in adults
via significant cold exposure
describe the structure of WAT (composition + shape)
contains one large lipid droplet, spherical
describe the structure of BAT (composition + shape)
smaller, contains multiple lipid droplets, polygonal, contain many more mitochondria, surrounded by a denser capillary network
which type of adipose is spherical
WAT
which type of adipose is polygonal
BAT
which type of adipose contains multiple lipid droplets
BAT
which type of adipose contains a single lipid droplet
WAT
what is another name for the uncoupling protein UCP1
thermogenin
describe what NORMALLY happens to protons after the formation of the proton gradient from the ETC
the protons would normally flow back into the matrix through ATP synthase to generate ATP
describe what happens to protons from the proton gradient of the ETC when thermogenin (uncoupling protein) is present
thermogenin forms a channel in the IMM to allow protons to flow back in WITHOUT generating ATP. Allows dissipation of the H+ gradient without building ATP = energy released as heat
T or F: thermogenin allows lots of ATP production
false; no ATP is made, and instead the energy formed is released as heat
which adipokine is secreted from adipocytes in a prolonged fast
adiponectin
briefly, what does adiponectin do (ie which general processes does it upregulate and downregulate)
upregulates energy-producing processes and downregulates energy-consuming processes
specifically, which processes does adiponectin upregulate/increase
uptake of FAs from blood into myocytes, rate of b-ox in myocytes, increases appetite