A sarcomere is best described as _______.

• a part of the sarcoplasmic reticulum

• a group of fascicles

• a group of myofibrils

• a unit within a myofibril

• All of the choices are correct.

Myofibrils are composed primarily of

• actin and myosin

• ATP and ADP

• troponin and tropomyosin

• fascia and tendons

• perimysium and endomysium

A motor unit typically includes

• muscle fibers only

• motor neurons only

• several motor neurons and one muscle fiber

• one motor neuron and several muscle fibers

• several motor neurons and several muscle fibers

Endomysium separates individual muscle fibers from each other.

• True

• False

A motor neuron and the muscle fibers that it controls constitute a motor unit.

• True

• False

A broad sheet of dense connective tissue that connects muscle to muscle is called _________________.

• aponeurosis

• ligament

• tendon

• fascia

The electrical impulse that triggers a contraction travels deep into a skeletal muscle fiber by means of:

• sarcoplasmic reticulum

• transverse tubules

• mitochondria

• motor end plates

• gap junctions

Neurotransmitter molecules are stored in vesicles within:

• myofibrils

• motor units

• motor end plates

• motor neuron endings

• sarcomeres

The enzyme acetylcholinesterase causes acetylcholine to:

• A) bind to actin

• B) be secreted from the motor end plate

• C) decompose

• D) form cross bridges

• E) None of the choices are correct.

Creatine phosphate:

• causes the decomposition of ATP

• causes the decomposition of ADP

• supplies energy for the synthesis of ATP

• supplies energy for the breakdown of ATP to ADP

• binds to Ach receptors