APK 2105C Lecture Notes - Lecture 44: Creatine Kinase, Anaerobic Glycolysis, Oxidative Phosphorylation

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Chapter 12, Lecture 5
Muscle Physiology
Skeletal muscle metabolism
o The mechanism for producing ATP in a myocyte will vary depending on the type
and the intensity of work
o Capillaries supply the muscle with nutrients
Glucose
Fatty acids
o How is ATP made in skeletal muscle cell
Varies on type of exercise and how hard you’re working (intensity)
The creatine-phosphate (CP) system
o When ATP utilization increases
ATP decreases
ATP is not stored in our cells—there’s SOME on hand, but it’s
made on demand
ADP increases
o Substrate-level and oxidative phosphorylation need a few seconds to get up to
speed to supply the needed ATP
o CP + ADP → ATP + creatine
Rxn happens with creatine kinase
Creatine kinase dephosphorylates the CP and attaches it to the ADP
This ATP fuels the cell until the rest of cellular respiration can happen
Metabolism changes with intensity
o Gradual shift from one predominating
system to another
o Light exercise vs. intense exercise
Light exercise
CP is used up
immediately
Anaerobic glycolysis
and oxidative
phosphorylation starts
before CP ends
There is a gradual shift
from 1 ATP source to
another
Can do sub maximal
activity for a long time because we get more oxygen and we can
do oxidative phosphorylation longer
Intense exercise
CP is used up within the first minute
Anaerobic glycolysis spikes a lot and then ends
Gradual incline in oxidative phosphorylation
Cannot do this type for a long time because anaerobic glycolysis
(main source of ATP) cannot continue for a long time
Clinical correlation = energy systems and activities
o As duration increases, intensity has to come down
o Submaximal exercise can be maintained for a long time
More aerobic mechanisms to maintain ATP needs
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