Q. Which of the following option shows correct order of some stages of muscle contraction from the beginning to the end of the process?
A) stimuli $\rightarrow$Neurotransmitter secretion$\rightarrow$ Release of $C{a^{2}}^{+} \rightarrow$Cross bridges formation$\rightarrow$Excitation of T-system$\rightarrow$ Sliding of action filaments
B) Stimuli$\rightarrow$ Neurotransmitter secretion$\rightarrow$Excitation of T-system $\rightarrow$Release of $Ca^{2^{+}} \rightarrow$Cross bridges formation $\rightarrow$ Sliding of actin filaments$\rightarrow$ ‘H’ band diminishes
C) Stimuli$\rightarrow$ Excitation of T-system$\rightarrow$ Neurotransmitter secretion$\rightarrow$ Cross bridges formation$\rightarrow$ sliding of action filaments$\rightarrow$ ‘H’ band diminishes
D) Stimuli$\rightarrow$ Neurotransmitter secretion$\rightarrow$ Cross bridges formation$\rightarrow$ Excitation of T-system$\rightarrow$ Sliding of action filaments
Explanation
The contraction of skeletal muscle includes ultrastructural and biochemical events. Ultrastructural events leads with stimuli excitation of T-system followed by crossbridge formation (myosin and actin filaments involved) and the cross bridge breakage. The biochemical events explain that stimuti leads to neurotransmitter secretion, excitation of T-system and release of $Ca^{2 +}.$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.