Muscle Contraction Mechanism

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What happens to the troponin molecule when calcium ions bind to it?

It releases the myosin head from the actin filament

It pulls the tropomyosin molecule away from the F actin (correct)

It moves towards the F actin

It breaks the actomyosin complex

What is the name of the theory that explains how actin filaments slide over myosin filaments during muscular contraction?

Sliding Theory

Walking Theory

Ratchet Theory

All of the above (correct)

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 (correct)

The actin filament is pushed away from the sarcomere

The tropomyosin molecule moves towards the F actin

The myosin head breaks away from the actin filament

What is the name of the complex formed during muscle contraction when actin filaments slide over myosin filaments?

Actomyosin complex (A) Signup and view all the answers

What is the role of calcium ions in the muscle contraction mechanism?

They bind to the troponin molecule (C) Signup and view all the answers

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 (D) Signup and view all the answers

What happens when acetylcholine is released from the motor endplate?

It opens the ligand-gated sodium channels. (A) Signup and view all the answers

What is the function of the 'T' tubules?

To rapidly spread action potential into the muscle fibre (D) Signup and view all the answers

What is the role of calcium ions in muscle contraction?

To form the link between excitation and contraction of the muscle (C) Signup and view all the answers

What happens to the active site of F actin in the relaxed condition?

It is covered by tropomyosin (A) Signup and view all the answers

What is the result of the action potential reaching the cisternae of 'L' tubules?

The release of calcium ions into the sarcoplasm (D) Signup and view all the answers

What happens when calcium ions move towards the actin filaments?

The muscle fibre contracts (D) Signup and view all the answers

What is the result of the graded potential hyperpolarizing the membrane potential?

Increased negativity (C) Signup and view all the answers

During muscle contraction, what happens to the actin filaments?

They glide over the myosin filaments (B) Signup and view all the answers

What is the process that occurs between the excitation and contraction of the muscle?

Excitation contraction coupling (A) Signup and view all the answers

What is the name of the complex formed during muscle contraction?

Actomyosin complex (C) Signup and view all the answers

What is the zone that is broad in the relaxed state of the muscle?

H zone (D) Signup and view all the answers

How many stages are involved in the molecular mechanism of muscular contraction?

3 (C) Signup and view all the answers