Which type of muscle fibres are primarily found in the gastrointestinal tract, and what is a key characteristic of their contraction?​

Correct option is B

The correct answer is (B) Smooth muscle fibres; slow and sustained involuntary contraction.

Explanation:

• The gastrointestinal (GI) tract is primarily composed of smooth muscle fibres. These muscles are involuntary, meaning they are not under conscious control.
• The contraction of smooth muscle fibres in the GI tract is characterized by being slow and sustained, which is essential for the continuous movement of food through the digestive system (peristalsis).

Information Booster:

• Smooth muscle fibres are found in the walls of internal organs, including the stomach, intestines, bladder, and blood vessels.
• The contraction is controlled by the autonomic nervous system and can continue for long periods without tiring.
• These muscles are not striated like skeletal muscles, and their contraction is smooth (hence the name).

Additional Information:

• (A) Striated muscle fibres: Found in skeletal muscles and cardiac muscles, these fibres have a striped appearance. Their contractions are typically forceful and voluntary in the case of skeletal muscles, not suited for the GI tract.
• (C) Cardiac muscle fibres: Found in the heart, these muscles have rhythmic contractions but are not present in the gastrointestinal tract.
• (D) Skeletal muscle fibres: These muscles are voluntary and are responsible for rapid and forceful contractions, such as those involved in movement. They are not found in the GI tract.