Muscular System Quest

The unit of muscle contraction, within the skeletal muscle, is the 

• sarcomere

• myofibril

• myofilament

• fascicle

•  

  muscle fiber

The perimysium surrounds the _________________ of the muscle.

•  

  muscle fiber

• myofibril

•  

  whole muscle

• fascicle

Only one filament slides in the "sliding filament theory" this is the 

•  

  m line.

• actin

•  z line.

• myosin

• myofibril

The "motor unit" is made of 

•  

  a motor neuron.

•  

  a neuromuscular junction.

•  

  All of the choices are correct except for "None of the answers..."

•  

  None of the choices are correct.

•  

  muscle cells.

The strength of a muscular contraction is directly related to 

•  

  the length of the axon of the motor unit.

•  

  how completely the contractile units contract.

•  

  the speed of the contraction.

•  

  the number of muscle fibers that contract.

If more muscle contracting force is required, then more motor units are used, and this is called______________________________.

• utilization

• compensation

• accommodation

• recruitment

When the contraction finally does occur, then each motor unit

•  

  contracts fully.

•  

  contracts to the extent that other surrounding motor units are contracting.

•  

  contracts some, unless the stimulus was great, then it may contract completely.

•  

  contracts to whatever extent that it was stimulated to contract.

When the myosin head pushes the actin myofilament toward the center of the sarcomere (M line) it's known as the 

•  

  power-stroke.

•  

  cross-bridge.

•  

  elasticity.

• climax

The sarcomere relaxes again and gears for another contraction when this molecule binds to the myosin head:

•  

  calcium ion

•  

  ADP

•  

  creatine

•  

  ATP

"Summation" is the adding up of muscle twitches/contractions (force) due to the stimulation of many

•  

  neuromuscular junctions.

•  

  motor units.

•  

  motor end plates.

• sarcomeres