- Exam
- NEET
- Subject
- Zoology
- Chapter
- Locomotion and Movement
NEET · Zoology · Locomotion and Movement
How does the increase in calcium ion level lead to muscle...
Options
- ABy increasing the cross-bridge formation between actin and myosin
- BBy binding with a subunit of troponin on actin filaments and thereby removing the masking of active sites for myosin
- CBy causing the return of ‘Z’ lines back to their original position
- DBy pumping calcium ions back to the sarcoplasmic cisternae
Correct answer
B. By binding with a subunit of troponin on actin filaments and thereby removing the masking of active sites for myosin
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 myosin.The globular head of the myosin filament is an active ATPase enzyme and has binding sites for ATP and active sites for actin