According to the all or none law, what is true about skeletal muscles?

According to the all or none law, what is true about skeletal muscles?

• A. Skeletal muscles can partially contract
• B. Skeletal muscles either fully contract or not at all
• C. Skeletal muscles contract only when stimulated multiple times
• D. Skeletal muscles can only contract under extreme stress

Answer: (B)

The all or none law states that a muscle fiber will either contract fully or not at all when it receives a sufficient stimulus. This principle applies to the functioning of individual muscle fibers rather than the entire muscle as a whole. When a muscle fiber is activated by a motor neuron and reaches the necessary threshold of stimulation, it will respond with a complete contraction; if the threshold is not met, there will be no contraction. This concept is critical in understanding how muscle contractions operate on a cellular level. Each muscle fiber behaves independently regarding contraction, so the overall strength of a muscle's contraction depends on how many muscle fibers are recruited and firing at a given time, rather than the degree of contraction of each individual fiber. Therefore, while a muscle as a whole may appear to "partially contract" due to some fibers being engaged and others not, the all or none law applies strictly to each muscle fiber's activation response.

The all or none law states that a muscle fiber will either contract fully or not at all when it receives a sufficient stimulus. This principle applies to the functioning of individual muscle fibers rather than the entire muscle as a whole. When a muscle fiber is activated by a motor neuron and reaches the necessary threshold of stimulation, it will respond with a complete contraction; if the threshold is not met, there will be no contraction.

This concept is critical in understanding how muscle contractions operate on a cellular level. Each muscle fiber behaves independently regarding contraction, so the overall strength of a muscle's contraction depends on how many muscle fibers are recruited and firing at a given time, rather than the degree of contraction of each individual fiber. Therefore, while a muscle as a whole may appear to "partially contract" due to some fibers being engaged and others not, the all or none law applies strictly to each muscle fiber's activation response.