Chapter 10 Lecture Quiz

Which connective tissue sheath surrounds each individual muscle fiber?

• epimysium

• endomysium

• endodermis

• perimysium

• endosacrosium

During muscle contraction, the ________ usually moves closer to the __________.

• origin on the less movable bone; insertion on the more movable bone

• insertion on the more movable bone; origin on the less movable bone

• origin on the more movable bone; insertion on the less movable bone

• insertion on the less movable bone; origin on the more movable bone

• none of the above

What myofilaments are present in the A band of sarcomeres?

• actin

• myosin

• sarcosin

• both a and b

• all of the above

When a muscle contracts concentrically, what part of the sarcomere disappears and why?

• A band; the overlap of thick filaments by thin filaments increases

• I band; thin filaments partially overlap thick filaments

• H Zone; thin filaments partially overlap thick filaments

• A band; thin filaments partially overlap thick filaments

• H zone; the overlap of thick filaments by thin filaments increases

What is the significance of the enzyme acetylcholinesterase in the synaptic cleft of the neuromuscular junction?

• it breaks down acetylcholine immediately after it causes a single contraction of the muscle fiber, preventing additional, unwanted contractions

• it causes the sarcolemma of the muscle fiber at the neuromuscular junction to invaginate and form T tubules, allowing deeper myofibrils to contract in synchrony with outer myofibrils

• it prevents the myosin filaments from moving out of place

• it produces the ATP needed for muscle contraction

• all of the above