Question

Compare and contrast smooth muscle cell contraction to skeletal muscle cell contraction. List two ways that smooth and skeletal muscle contraction are similar, and list two ways in which smooth and skeletal muscle contraction are different.

Answer 1

Two differences in the contraction of smooth and skeletal muscles:-

• Smooth muscles have a slower contraction speed than the skeletal muscles. It is due to the following reasons:-

1. Slower diffusion rate of calcium ions.
2. Slower cross- bridge formation.
3. Rate of action potential propagation.

• Unlike skeletal muscle, smooth muscle does not contain the calcium-binding protein troponin. Due to the absence of troponin, cross- bridge formation is not regulated by the troponin-ntropomyosin complex but instead by the regulatory protein Calmodulin.

Two similarities in the contraction of smooth and skeletal muscles:-

• In both the muscles, contraction is caused by the sliding of myosin and actin filaments (a sliding filament mechanism) over each other. The energy for this to happen is provided by the hydrolysis of ATP.
• Both the muscles are electrically excitable in the same way.