Question

The long refractory period is found in
A. White fibres of skeletal muscles
B. Red fibres of skeletal muscles
C. Smooth muscles
D. Cardiac muscles

Answer 1

Muscle tissues are soft and present along with bone to perform a mechanical activity, like pushing, pulling, lifting and some other activity. Muscle cells contain actin and myosin protein filament, which slide and produce contraction that changes the length and shape of the cell.

Complete answer:
Refractoriness is the basic property of the object of autowave nature, the refractory period is a period in which an organ or cell is incapable of repeating a particular action, it is majorly referred to as an electrically excitable muscle cell or neurons.
The absolute refractory period is depolarization and repolarization, while the relative refractory period refers to hyperpolarization. The refractory period is 0.002-0.005 sec in skeletal muscle fibre while in the case of cardiac muscles fibre it takes 0.1-0.2 sec, it is the interval in which muscle fibre is unable to respond. The long refractory period in cardiac muscle is important because if the refractory period is short then the heart could enter into a summation phase, which is when a muscle gets stimulated rapidly and muscle does not have time to relax in between stimulus. This will resist tetanus that occurs from and each contraction will get enough time to allow it to refill with blood before occurring of next contraction.
Muscle tissue arises from the mesodermal layer by myogenesis process, it is divided into three types of muscles, such as skeletal, cardiac, and smooth, and the action of muscle can be voluntary and involuntary. cardiac and smooth muscles are involuntary in action while skeletal muscles are voluntary in action, produce force and motion, the skeletal muscles divided into slow and fast-twitch fibres.
Hence, the correct option is B.

Note: Muscles are mainly responsible for changing and maintaining the posture, locomotion, and movement of an internal organ, like contraction of heart and peristalsis movement of the digestive tract.