Sliding theory states that

Question

Question

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AIIMS BSc NURSING 2024 Memory-Based Paper

Answer 1

The correct answer is Actin and myosin filaments do not shorten they only pass each other.

Concept:

The sliding filament theory is a widely accepted explanation for how muscles contract to produce force. It was first proposed by scientists Huxley and Hanson in the 1950s.
According to this theory, muscle contraction occurs when the thin actin filaments slide past the thick myosin filaments, causing the sarcomere (the functional unit of a muscle fiber) to shorten.
During contraction, the myosin heads bind to actin, forming cross-bridges, and then pull the actin filaments toward the center of the sarcomere through a series of power strokes.
This sliding of filaments does not involve any shortening of the filaments themselves; instead, it is the relative movement of the actin and myosin filaments that leads to muscle contraction.

Explanation:

Actin and myosin filaments do not shorten; they only pass each other.

This is the correct answer. The sliding filament theory describes that during muscle contraction, the actin and myosin filaments slide past one another without changing their length, leading to the shortening of the sarcomere and thus the muscle itself.

Other Options:

Actin and myosin filaments shorten and slide past each other.
- This is incorrect because the actin and myosin filaments do not shorten during muscle contraction. They remain the same length but slide past each other to create the shortening of the muscle.
When myofilaments slide past each other, shortening of actin filaments occur.
- This is incorrect because actin filaments do not shorten. The sliding filament theory specifies that it is the sliding of the filaments, not their shortening, that leads to muscle contraction.
When myofilaments slide past each other, shortening of myosin filaments occur.
- This is incorrect because myosin filaments do not shorten. Similar to actin, the myosin filaments remain the same length and it is their sliding action relative to the actin filaments that causes contraction.