18 Questions
What happens to the troponin molecule when calcium ions bind to it?
It pulls the tropomyosin molecule away from the F actin
What is the name of the theory that explains how actin filaments slide over myosin filaments during muscular contraction?
All of the above
What is the result of the tilting movement of the myosin head during muscle contraction?
The actin filament is dragged along with the myosin head
What is the name of the complex formed during muscle contraction when actin filaments slide over myosin filaments?
Actomyosin complex
What is the role of calcium ions in the muscle contraction mechanism?
They bind to the troponin molecule
What is the result of the repeated tilting movement of the myosin head during muscle contraction?
The actin filaments are pulled towards the centre of the sarcomere
What happens when acetylcholine is released from the motor endplate?
It opens the ligand-gated sodium channels.
What is the function of the 'T' tubules?
To rapidly spread action potential into the muscle fibre
What is the role of calcium ions in muscle contraction?
To form the link between excitation and contraction of the muscle
What happens to the active site of F actin in the relaxed condition?
It is covered by tropomyosin
What is the result of the action potential reaching the cisternae of 'L' tubules?
The release of calcium ions into the sarcoplasm
What happens when calcium ions move towards the actin filaments?
The muscle fibre contracts
What is the result of the graded potential hyperpolarizing the membrane potential?
Increased negativity
During muscle contraction, what happens to the actin filaments?
They glide over the myosin filaments
What is the process that occurs between the excitation and contraction of the muscle?
Excitation contraction coupling
What is the name of the complex formed during muscle contraction?
Actomyosin complex
What is the zone that is broad in the relaxed state of the muscle?
H zone
How many stages are involved in the molecular mechanism of muscular contraction?
3
This quiz covers the process of muscle contraction, including the role of calcium ions, troponin, and tropomyosin in uncovering the active site of F actin and the formation of the actomyosin complex.
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