question_answer

Sliding filament theory can be best explained as               

A)  when myofilaments slide pass each other actin filaments shorten while myosin filament do not shorten

B)  actin and myosin filaments shorten and slide pass each other

C)  actin and myosin filaments do not shorten but rather slide pass each other

D)  when myofilament slide pass each other myosin filament shorten while actin filaments do not shorten

Correct Answer: C

Solution :

Sliding filament theory is explained as actin and myosin filaments do not shorten but rather slide pass each other. Two groups of workers, i.e. Andrew Huxley and Ralph Niedergerke (1954) and Hugh Huxley and lean Hanson (1954) proposed the sliding filament theory. It has essential features as follows:

(i) During   muscle   contraction   the   thin myofilaments show sliding inward towards H-zone.

(ii) The sacromere shortens, without changing the length of thin and thick myofilaments.

(iii) The cross bridge of thick myofilaments connect with portions of thin myofilaments. These cross bridges move on the surface of the thin myofilaments resulting to sliding of thin and thick myofilaments over each other.

(iv) The lengths of thick and thin myofilaments do not change thin filament (actin) during muscle contraction.