2020 - Muscle quiz 2

Each thin filament consists of

• two actin protein strands coiled around each other

• chains of myosin molecules

• a rod-shaped structure with "heads" projecting from each end

• a double strand of myosin molecules

At rest, tropomyosin is held in place by

• actin molecules

• myosin molecules

• troponin molecules

• calcium ions

When the skeletal muscle fiber contracts, the

• H bands and I bands get larger

• zones of overlap get larger

• Z discs move further apart

• width of the A band increases

Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle

• lengthens

• shortens

• weakens

• pulls from the middle

The complex of a transverse tubule and two adjacent terminal cisternae is known as a

• trimer

• triad

• trisome

• trilogy