- Exam
- NEET
- Subject
- Zoology
- Chapter
- Locomotion and Movement
NEET · Zoology · Locomotion and Movement
How does the cycle of cross-bridge formation and breakage lead to...
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 masking of active sites for myosinThe globular head of the myosin filament is an active ATPase enzyme and has binding sites for ATP and active sites for actin.
The cycle of cross-bridge formation and breakage causes further sliding of actin