Question

List and briefly describe the mechanisms for smooth muscle contraction in terms of altering (increasing) the force of contraction.

Answer 1

The contraction of smooth muscle is brought by sliding of actin and myosin filaments over each other. The steps involved are-

1. Release of calcium from endoplasmic reticulum whenever any stimulus comes.

2. This calcium then bind with calmodulin and activate myosin light chain kinase.

3. Kinase enzyme increase release of ATP and cause phosphorylation of myosin light chain.

4. This cause sliding of actin and myosin over each other by forming a cross bridge.

formation of cross bridge between actin and myosin cause increase in force of contraction of muscle.

when more calcium is released from endoplasmic reticulum, more fibres are stimulated and it cause increase in force of contraction.