Lecture 6 - CHO metabolism during exercise Flashcards
liver glucose output is subject to _____, _____ controls
multiple, redundant
Training reduces reliance on ___ as a fuel source
CHO
What converts Pyruvate to Lactate?
lactate dehydrogenase
Early on in exercise the rate of glycogen breakdown is..
most rapid
When glycogen runs out, this is associated with
exhaustion - assoicated with fatigue
What are the factors that regulate glycogen breakdown?
Ca2+, Pi - the important local stimuli, will activate glycogen phosphorylase
Adrenaline - activates b receptors, stimulates glycogen breakdown
Muscle [glycogen] - offset slightly, but still advantageous to load muscle with glycogen = more of it
FFA - reciprocally increases/decreases
Temperature - direct effect of muscle temp - speeds up rate of reaction. Also supplies more adrenaline
Trained individuals will reduce the amount of glycogen breakdown at a certain intensity because
there is less adrenaline
better regulation of your ATP turnover so the increase in Pi is not as high
What are the determinants of glucose uptake into the muscle?
diffusion gradient
concentration in the capillaries
amount of GLUT 4 at the membrane
metabolism - hexokinase activity
over time if the glucose concentration falls..
the glucose uptake is effected
Glycogen in the muscle will reduce…
the glucose uptake (leaves it for the CNS)
Adrenaline doesn’t necessarily influence glucose uptake, but does effect….
glycogen breakdown
Liver glucose output is closely matched with…
muscle glucose uptake - but elongated exercise period cause liver glucose output to fall (there is a finite capacity)
Is there glyocogen in the liver?
yes - broken down by _______
Gluconeogenesis is mainly done in the …
liver, but also kidney and muscle
an hour of exercise will drop liver glycogen levels by.
50%
Glucagon will stimulate the enzymes involved in…
gluconeogenesis
What are the factors which regulate liver glucose output during exercise?
feedforward and feedback mechanisms:
insulin (downreg.) and glucagon (from pancreas)
Adrenaline
Sympathetic nerves
Liver [glycogen] - if there’s more of it, more will be broken down (same as in muscle)
Blood [glucose] - when injested the endogenous glucose production is reduced - its already there from the GIT
The liver is supplies by blood circulation from the…
Gut and pancreas
After training there’s a reduction in _____ uptake and oxidation
glucose uptake and oxidation
PDH activity goes down over time during exercise causing ..
a reduction of CHO oxidation - PDH a the rate limiting enzyme
Liver glucose output is closely matched with Glucose ____
uptake
What can be converted to glucose in the liver
AA, glycerol, Pyruvate, lactate
process called gluconeogenesis
Does the muscle perform gluconeogenesis?
only a very small amount - during recovery
The kidney does a little but as well in the fasted state
