Question

(a) Explain the physiological mechanism of excitation-contraction coupling in skeletal muscle.

(b) Draw links between excitation-contraction coupling, EMG, and dynamometry.

Answer 1

a)excitation-contraction coupling

1.an action potential produced at pre-synaptic terminal in the neuromuscular junction is propogated along sarcolemma of the skeletal muscle.depolarisation also spreads along membrane of T-tubules

2.depolarisation of T-tubules causes gated Ca2+ channels in sarcoplasmic reticulum to open,resulting in an increase in permeability of SR to Ca2+,especially in terminal cisternae.calcium ions then diffuse from SR to sarcoplasm.

3.calcium ions released from SR bind to troponin molecules,troponin molecules bound to G ctin molecules are released,causing tropomyosin to move,exposing active sites on G actin

4.once active sites on G actin molecules are exposed,heads of myosin myofilaments bind to them to form cross bridges

here is a picture to better understand the following explanation