Home › CBSE Class 11 › Biology › Locomotion and Movement › During muscle contraction, the immediate trigger…
During muscle contraction, the immediate trigger for actin-myosin binding is the release of:
AAcetylcholine into the synaptic cleft area
BSodium ions into the muscle cytoplasm area
CCalcium ions (Ca²⁺) from sarcoplasmic reticulum
DPotassium ions out of the muscle cell area
Answer & Solution
Correct answer: C. Calcium ions (Ca²⁺) from sarcoplasmic reticulum
Action potential → Ca²⁺ released from SARCOPLASMIC RETICULUM into sarcoplasm → Ca²⁺ binds TROPONIN → tropomyosin shifts off actin's myosin-binding sites → myosin heads attach + pull actin (power stroke). Ach triggers AP but Ca²⁺ is the immediate intracellular trigger.
Related questions
An autoimmune disease attacking the neuromuscular junction and causing weakness is:The joint between the atlas and axis that lets you shake your head is a:Skull bones fuse with sutures and cannot move. This joint type is:When a muscle moves a bone, the joint acts as the:The collar bone is properly called the:The knee cap is a cup-shaped bone called the:The last two pairs of ribs are not attached in front, so they are called:The first vertebra, which meets the skull's occipital condyles, is the: