Know Your Motor Unit Energy Metabolism Running a Marathon The  -Motoneuron Muscle Glucose Uptake

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 co- factor, 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?