Assertion : Smooth muscle fibres do not appear to be striated.
Reason : There is a regular alternate arrangement of thick and thin filaments in smooth muscle fibre.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

C

Explanation

A muscle fibre appears to be striated if the thick and thin myofilaments, i.e., the myosin and actin filaments are arranged in a regular and alternate manner in the fibre giving rise to light and dark bands. Striated or skeletal muscle fibres show this type of striations because of the organised arrangement of myofilaments. Cardiac muscles also show faint striations. But these striations are entirely absent in smooth muscle fibres because of the absence of a regular arrangement of myofilaments. This is the reason why they are also known as unstriated or non-striated muscle fibres.