NEETZoologyLocomotion and Movement
How does the cycle of cross-bridge formation and breakage lead to muscle contraction?
Options
- ABy breaking the cross-bridge
- BBy increasing the cross-bridge formation between actin and myosin
- CBy reducing the ‘I’ bands and retaining the length of the ‘A’ bands
- DBy pumping calcium ions back to the sarcoplasmic cisternae
Correct answer
C. By reducing the ‘I’ bands and retaining the length of the ‘A’ bands
Step-by-step solution
Muscle contraction is initiated by a signal sent by the central nervous system (CNS) via a motor neuron.The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction or motor-end plate.When a neural signal reaches the neuromuscular junction, it releases a neurotransmitter (Acetylcholine) which generates an action potential in the sarcolemma.Increase in Ca²⁺ level leads to the binding of calcium with a subunit of troponin on actin filaments and thereby remove the mas