Muscle Physiology Unit Exam Review

What is the main factor that determines the power of a muscle?

• the length

• the shape

• the number of neurons innervating it

• the total number of muscle cells available for contraction

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

• calcium ions returning to the terminal cisternae

• the tropomyosin blocking the myosin once full contraction is achieved

• acetylcholinesterase destroying the ACh

• the action potential stops going down the overloaded T tubules

Which of the following is the correct sequence of events for muscle contractions?

• motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

• neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke

• muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments

• neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke

Which of the choices below does not describe how recovery oxygen uptake (oxygen deficit) restores metabolic conditions?

• converts lactic acid back into glycogen stores in the liver

• resynthesizes creatine phosphate and ATP in muscle fibers

• increases the level of lactic acid in the muscle

• replaces the oxygen removed from myoglobin

Creatine phosphate functions in the muscle cell by ________.

• forming a temporary chemical compound with myosin

• forming a chemical compound with actin

• inducing a conformational change in the myofilaments

• storing energy that will be transferred to ADP to resynthesize ATP

What structure in skeletal muscle cells functions in calcium storage?

• sarcoplasmic reticulum

• mitochondria

• intermediate filament network

• myofibrillar network

Excitation-contraction coupling requires which of the following substances?

• Ca2+ and ATP

• Ca2+ only

• ATP only

• ATP and glucose

Muscle fibers that are designed for endurance, contract slowly, and have a steady supply of energy.

• Actin

• Slow-twitch muscle fibers

• Fast-twitch muscle fibers

• Troponin

Someone who has broken an arm and has had a cast on it for months will notice a distinct shrinking of the arm once the cast is removed. Why does this happen?

• The cast has reduced blood flow to the muscle tissue to reduce swelling.

• Muscles that are not used will atrophy.

• The other arm was used more to compensate for the unused one, and it has become stronger.

• If the person was right-handed, he or she will become left-handed.

What is the result of resistance exercise?

• Existing muscle cells increase in diameter.

• The number of muscle cells increases.

• More mitochondria develop.

• New blood vessels develop.