Muscle Organization

A motor neuron and all the muscle fibers it supplies is called a(n) ____________.

• axon terminal

• motor unit

• synaptic cleft

• motor end plate

• motor unit

Which of the following does NOT occur during skeletal muscle contraction?

• Myosin heads bind to actin

• Calcium concentration in the sarcoplasm increases

• Calcium binds to myosin heads

• The I bands shorten and H zones disappear

• ATP is hydrolyzed

The functional unit of contraction in a skeletal muscle fiber is the ____________.

• myofibril

• sarcoplasmic reticulum

• sarcomere

• myofilament

• sarcolemma

In the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and _________.

• thin filaments

• troponin

• actin

• myosin

• tropomyosin

"Cross bridges" that link between the thick and thin filaments are formed by the ___________.

• tails of myosin filaments

• globular head of thick filaments

• globular actin

• F actin

A sarcomere is part of a(n) ___________.

• myofibril

• myofilament

• perimysium

• endomysium

• Actin

This happens in a contracted skeletal muscle fiber

• A band vanishes

• M line vanishes

• H zone elongates

• I band is steady

Calcium, during muscle contraction binds with

• Tropomyosin

• TpI

• TpT

• TpC

White muscles are not used in this function:-

• eyeball movement

• sustained work at a slower pace for a prolonged period

• fast flights of sparrows

• strenuous and fast work for short duration of time

Duration of one muscle twitch is

• 0.1 seconds

• 1 second

• 5 seconds

• 10 seconds