Question

13. During skeletal musele contraction, whet substance does the sarcoplasmic reticulum store and release? A. acetyicholine B. sodium D. calcium 34. What stimalates the sarcoplasmic reticulum (SR) to release this chemical? A. the voltage change from the muscular action potential traveling down the transverse (1) tubules B. the binding of acetylcholine to ligand-gated channels in the transverse tubules C. direct stimulus from the neural action potential D, the binding of myosin to actin 35. Transverse (T) tubales are extensions of the A. sarcoplasmie reticulum B. sarcolemma in skeletal muscle. C. junctional folds D. cytoskeleton E. thick filament 36. Before a myofiber can contract, calcium must first bind to A. calsequestrin B. myosin C. actin D. troponim E. tropomyosin to roll off the active site. A. tropomyosin B, actin-myosin complex C. myosin bead D, myosin tail 38. "Power stroke" in skeletal muscle contraction refers to A. flooding the sarcoplasm with calcium B. release ofacetylcholine from the motor neuron via exocytosis C. increase in the permeability to sodium following acetylcholine binding D. pulling the tendon on the bone as a whole muscle contracts E. the swiveling of the myosin heads as they connect with and move actin filaments 39. For muscle relaxation to occur, the muscle fiber needs A. presence of acetylcholine (ACh) B. free calcium C. an end plate potential on the myofiber D. an action potential generated from the trigger zone E. ATP

Answer 1

33) ANSWER is : D calcium

EXPLANATION:

Sarcoplasmic reticulum store and releases calcium during muscle contraction. Stores large amounts of calcium as calcium, when released, involved in muscle contraction. When skeletal muscles release calcium it contract by receiving signals from neurons and control muscle movement.

34) ANSWER is : binding of acetylcholine to ligand-gated channels in the transverse tubules

EXPLANATION :

Acetylcholine binds to protein receptors on the sarcolemma of the muscle fiber. Stimulates the release of calcium ions from the sarcoplasmic reticulum.

The release of calcium ions into the sarcoplasm of the muscle fiber and also the presence of ATP will cause the muscle fiber to contract


35) ANSWER is : B. sarcolemma

EXPLANATION :

T tubules are extensions of the sarcolemma in skeletal muscle.

Transverse tubules, are tunnel-like extensions of sarcolemma and passes through muscle cells from one side of cell to other.


36) ANSWER is : D. troponin

EXPLANATION:

Before a myofiber can contract, calcium must first bind to troponin

The first step in the process of contraction is for calcium to bind to troponin and tropomyosin can slide away from the binding sites on the actin strands...