Create a difficult multiple choice question on ExcitationCon

Create a difficult multiple choice question on Excitation-Contraction coupling and relaxation that centers on the action of Ca^2+. This question should require the ‘test taker’ to understand how multiple steps are linked together in E-C coupling to create contraction and/or relaxation of a muscle. Be sure to have at least four answers to choose from (i.e. A – D), and don’t forget to state the correct answer!

Solution

What happens during Excitation -Contraction coupling and relaxation ?

A.Calcium ions are released from the sarcoplasmic reticulum and bind to tropomyosin.

B.The binding of myosin heads to actin filaments is blocked by troponin.

C.Excretion of calcium ions from the muscle fibres causes relaxation.

D,The action potential generated at the muscle travels along the sarcolemma towards the transverse tubules.

The correct answer is : D

Reason.The sarcoplasmic reticulum to release Ca2+ in response to action potential generated at the muscle.This calcium ions binds to troponin and pulls the tropomyosin away, allowing cross-bridges (CBs) to be formed by interaction of myosin and actin filaments thus,initiating CB cycling.When Ca2+ is taken back up into the sarcoplasmic reticulum, relaxation occurs.