Know Your
Motor Unit
Energy
Metabolism
Running
a
Marathon
The
-Motoneuron
Muscle
Glucose
Uptake
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It is likely to be higher for the motor
units of the gastrocnemius than for the
motor units of the occular muscles
What is the ratio of muscle fibers per
nerve?
This principle first described by Elwood
Henneman defines the recruitment order
of motor units.
What is the “size principle”?
These define a motor unit.
What is the -motorneuron and
the muscle fibers it innervates?
These types of runners recruit
more motor units at one time.
Who are sprinters?
Motor units recruited last
generate more of this, but take
longer to do this.
What are tension and relax?
This macronutrient gives the
most ATP per carbon atom
What are fatty acids?
This is the most immediate
source of high energy phosphate
for ATP synthesis.
What is Creatine phosphate?
ATP is required for this important
step in fatty acid metabolism
What is fatty acid acylation?
This reaction results in the
regeneration of the essential cofactor, NAD, during anaerobic
glycolysis.
What is the reduction of pyruvate
to lactate catalyzed by lactate
dehydrogenase?
These are the primary macronutrients
used during a 400 meter dash.
What are carbohydrates?
This is the primary source of ATP at the
end of a marathon.
What are free fatty acids?
The primary muscle fibers used
early in a marathon.
What are Type 1 or slow,
oxidative muscle fibers?
These are the two most important
pathways in preserving muscle
glycogen and maintaining blood
glucose at the end of a marathon.
What are gluconeogenesis and
lipolysis?
The work rate that a marathon
runner should compete at for the
first 20 miles is just below this
metabolic marker.
What is the Anaerobic Threshold
or the Onset of Blood Lactate
Accumulation?
Marathon runners “carbo load” to
sustain this valuable energy
source
What is Muscle Glycogen?
These send nerve impulses to
muscle spindles in parallel with
impulses from -motoneurons.
What are -motoneurons?
These sensors send afferent
signals that inhibit motoneurons, protecting muscle
from injury due to excessive
muscle tension.
What are the Golgi Tendon
Organs?
These cells secrete myelin which
accelerate transmission of the
action potential down the nerve
axon.
What are Schwann cells?
These receptors provide feedback
to the -motoneuron that
participate in control of muscle
stretch.
What are muscle spindles?
The sum of EPSP and IPSP from
central and afferent signals must
reach activation threshold at this motoneuron site to cause an action
potential.
What is the axon hillock?
An increase in this causes an
increase in the rate and a change
in the fate of muscle glucose
uptake
What is exercise intensity?
This AMP-stimulated enzyme
has been postulated to be a key
regulator of glucose uptake
during exercise.
What is AMP-activated protein
kinase?
These three serial physiological
processes are required for muscle
glucose uptake.
What are (1) extracellular
glucose delivery, (2) membrane
glucose transport, and (3)
intramyocellular glucose
phosphorylation to muscle?
Muscle glucose uptake in the
fasted subject can cause
hypoglycemia if it exceeds the
sum of these pathways.
What are hepatic glycogenolysis
and gluconeogenesis?
This member of the Department’s
Circle of Distinguished Alumni
first described this mechanism
for glucose transport across the
membrane, such as occurs during
muscle contraction
Who is Dr. Kono and what is the
translocation of glucose
transporters?