ESS 345 MIDTERM EXAM QUESTIONS AND ANSWERS
WITH COMPLETE SOLUTIONS VERIFIED LATEST UPDATE
Thick filaments are often named for which protein?
Myosin
A motor unit refers to ---
A single motor neuron plus all of the muscle fibers it innervates
Why is it necessary to have an action potential (electrical signal) in the muscle for contraction?
The SR will release Ca2+ only if it has been electrically stimulated
According to the size principle, which motor neuron unit will be recruited first for a task?
The motor unit with the smallest motor neuron
What is a twitch summation?
A means by which gradation of muscle contraction may be accomplished
Increasing the frequency at which motor units are firing within a muscle
If you wanted to pick up something heavier than your pencil (such as your book), you would need to
have a stronger muscle contraction. In what way might you accomplish this?
Stimulate more motor neurons
If you want to hold a very heavy dumbbell to show your friends how strong you are, you want to
select the best joint angle -------
,Where muscle length is optimal and leverage is maximal
During concentric contractions, increasing the speed of contraction will -----
decrease the force produced
The --- is the basic of contraction in skeletal muscle
Sarcomere
Myofibril is --- of muscle fiber
Composed
At rest --- is stored in the sarcoplasmic reticulum (SR) and released by an action potential to bind to ---
for muscle contraction
Calcium
Troponin
At the end of contraction phase, myosin bound --- which --- the cross-bridges
Actin
Maintains
At rest, cross bridge interaction between actin and myosin in skeletal muscle is directly blocked by ---
Tropomyosin
When the myosin head pulls the thin filament toward the center of the sarcomere, the tilting action of
the head is called ---
Powerstroke
, Type --- fibers are typically engaged during short, higher-intensity exercise that involves some degree
of endurance
IIa
Type --- fibers are not very easily stimulated by the nervous system, meaning that they typically are
not engaged until all the other fiber types have been stimulated first
IIx
When maximal force is produced, type --- fibers are used
I, IIa, IIx
--- is the oxygen-binding molecule associated with skeletal muscle
Myoglobin
To form a cross-bridge, actin binding site to myosin must be --- and myosin head must be energized by
---
Exposed
ATP breaking into ADP + Pi
If for some reasons less Ca2+ is released from sarcoplasmic reticulum (SR), what would happen to
force production and why?
Force production would decrease b/c force production is dependent on the amount of Ca2+ (size of SR)
in that a greater amount of Ca2+ allows more cross bridges to be formed. When released, Ca2+ attaches
to troponin which shifts causing tropomyosin to also shift to expose actin myosin binding site. This allows
myosin to the myosin binding site on the actin to form a cross bridge. A cross bridge sets the stage for a
power stroke in which the muscles contract to generate force. Without the formation of a cross bridge a
WITH COMPLETE SOLUTIONS VERIFIED LATEST UPDATE
Thick filaments are often named for which protein?
Myosin
A motor unit refers to ---
A single motor neuron plus all of the muscle fibers it innervates
Why is it necessary to have an action potential (electrical signal) in the muscle for contraction?
The SR will release Ca2+ only if it has been electrically stimulated
According to the size principle, which motor neuron unit will be recruited first for a task?
The motor unit with the smallest motor neuron
What is a twitch summation?
A means by which gradation of muscle contraction may be accomplished
Increasing the frequency at which motor units are firing within a muscle
If you wanted to pick up something heavier than your pencil (such as your book), you would need to
have a stronger muscle contraction. In what way might you accomplish this?
Stimulate more motor neurons
If you want to hold a very heavy dumbbell to show your friends how strong you are, you want to
select the best joint angle -------
,Where muscle length is optimal and leverage is maximal
During concentric contractions, increasing the speed of contraction will -----
decrease the force produced
The --- is the basic of contraction in skeletal muscle
Sarcomere
Myofibril is --- of muscle fiber
Composed
At rest --- is stored in the sarcoplasmic reticulum (SR) and released by an action potential to bind to ---
for muscle contraction
Calcium
Troponin
At the end of contraction phase, myosin bound --- which --- the cross-bridges
Actin
Maintains
At rest, cross bridge interaction between actin and myosin in skeletal muscle is directly blocked by ---
Tropomyosin
When the myosin head pulls the thin filament toward the center of the sarcomere, the tilting action of
the head is called ---
Powerstroke
, Type --- fibers are typically engaged during short, higher-intensity exercise that involves some degree
of endurance
IIa
Type --- fibers are not very easily stimulated by the nervous system, meaning that they typically are
not engaged until all the other fiber types have been stimulated first
IIx
When maximal force is produced, type --- fibers are used
I, IIa, IIx
--- is the oxygen-binding molecule associated with skeletal muscle
Myoglobin
To form a cross-bridge, actin binding site to myosin must be --- and myosin head must be energized by
---
Exposed
ATP breaking into ADP + Pi
If for some reasons less Ca2+ is released from sarcoplasmic reticulum (SR), what would happen to
force production and why?
Force production would decrease b/c force production is dependent on the amount of Ca2+ (size of SR)
in that a greater amount of Ca2+ allows more cross bridges to be formed. When released, Ca2+ attaches
to troponin which shifts causing tropomyosin to also shift to expose actin myosin binding site. This allows
myosin to the myosin binding site on the actin to form a cross bridge. A cross bridge sets the stage for a
power stroke in which the muscles contract to generate force. Without the formation of a cross bridge a
