AP Unit 8 Quick Recall

What structure divides the skeletal muscle into compartments and contains collagen fibers, elastic fibers, blood vessels, and nerves?

• fascicle

• endomysium

• perimysium

• epimysium

Structures filled with extracellular fluid, formed by the tunneling of the sarcolemma through the muscle fiber, are called

• transverse tubules (T tubules).

• sarcomeres.

• sarcoplasmic reticulum.

• myofibrils.

Which of the following accurately lists the levels of organization within a muscle from largest to smallest?

• muscle fiber, myofilament, myofibril

• myofilament, myofibril, muscle fiber

• muscle fiber, myofibril, myofilament

• Z line, A band, I band, M line

Which of the following parts of a sarcomere connects thick filaments to one another?

• M line

• Z line

• troponin

• titin

If the sarcoplasmic reticulum were to rupture, what immediate effect might this have on the muscle cell?

• The cell would be in a state of flaccid paralysis.

• A muscle contraction would begin.

• The cell could no longer conduct action potentials.

• The cell would begin to atrophy.

Both the synaptic cleft and the motor end plate contain which of the following enzymes?

• acetylcholine

• acetylcholinesterase

• nicotinamide reductase

• serotonin decarboxylase

The presence of _________ at the myofilaments begins a contraction.

• calcium

• acetylcholine

• acetylcholinesterase

• sodium

The activation of more motor units rather than increasing the rate of stimulation is important for

• recruitment.

• incomplete tetanus.

• complete tetanus.

• summation.

What would happen if the acetylcholinesterase were destroyed?

• It would destroy the action potential.

• Sodium would flow in the opposite direction.

• The muscle fiber would be unable to relax.

• The muscle would take longer to excite.

The first action of ATP during a muscular contraction is

• to recock the myosin head.

• to pump calcium ions into the sarcoplasmic reticulum.

• to break the link between the myosin head and active site.

• to open sodium channels on the sarcolemma.