Questions 43 - 47
Starvation
43. Liver Glycogenolysis
•
Which step is NOT INVOLVED the
mobilization of liver glycogen?
A.
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30
10
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An increase in the activity of glycogen phosphorylase
fundamental to glycogenolysis
B.
The activation of adenylyl cyclase
the first step in making cAMP
C.
An increase in intracellular cyclic-AMP (cAMP) concentration
cAMP stimulates protein kinase A
D.
Phosphorylation of protein kinase A
activated allosterically by cAMP
E.
Phosphorylation of glycogen phosphorylase
the major way in which phosphoryase is activated
44. Muscle Glycogenolysis
•
Why doesn’t muscle glycogen contribute
significantly to blood glucose homeostasis
during starvation?
A.
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15
16
B.
C.
3
10
D.
E.
Because muscle does not express glucose 6-phosphatase
lack of G6Pase makes it hard to release glucose
Because muscle does not express phosphorylase
muscle phosphorylase is important in exercise
Because muscle does not store enough glycogen
muscle stores more than liver (in total)
Because muscle has non-branched glycogen
liver and muscle glycogen are structurally similar
Because muscle has a glycogen synthase that is insensitive to G6P
GS can respond to G6P in both liver and muscle
– but this is irrelevant to release of glucose
45. Lipolysis in Starvation
•
What would be the consequences of
inhibition of lipolysis during the first few
days of starvation?
A.
45
17
9
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B.
C.
D.
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E.
Blood ketone body concentration would rise
need fatty acids to make ketone bodies
Blood glucose concentration would rise
if alternate fuels not used, glucose will rapidly fall
Blood fatty acid concentration would rise
lipolysis releases fatty acids into the blood
There would be fewer substrates for gluconeogenesis in the liver
less glycerol, also less lactate (indirectly)
Fatty acid oxidation in the muscles would increase
FA oxidation rate proportional to blood [FA]
46. Regulation of PDH
•
What statement BEST DESCRIBES the
regulation of muscle pyruvate dehydrogenase
(PDH) during starvation
A.
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B.
C.
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During the first three days of starvation, PDH is fully activated but it
gets gradually switched off as starvation progresses
need to switch PDH quicky …. and keep it off
PDH becomes progressively more dephosphorylated during starvation
dephosphorylation ACTIVATES PDH
PDH kinase is activated during the first 48 h and stays active to the
end
phosphorylation (and inactivation) is by PDH kinase
D.
PDH phosphatase becomes progressively more active as starvation
progresses
need to keep PDH phosphatase inhibited
E.
PDH becomes more active as starvation progresses
10
need to keep PDH off
47. Ketone Bodies
•
Which statement about ketone bodies is
INCORRECT?
A.
Ketone bodies circulate in the blood stream bound to special carrier
proteins
freely soluble
24
B.
Ketone bodies can be used the peripheral tissues as well as the brain
used in any tissue with mitochondria
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C.
Ketone bodies can spontaneously decarboxylate to give acetone
acetoacetate to acetone happens a lot
Ketone body oxidation requires a source of Coenzyme A
very similar to fatty acid oxidation – make acetyl CoA
Ketone body oxidation will inhibit glucose oxidation
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D.
E.
as with fatty acid oxidation – acetyl CoA inhibits PDH