About the relation tension/length in skeletal muscle fibers, mark the right claim.
Options:
A. The passive tension is always present, in active and passive conditions, when the muscle length is adequate to generate elastic forces.
B. The passive tension is the tension developed only when the muscle is relaxed.
C. The total tension is the tension developed by the engaged cross-bridges.
D. The passive tension is always present, in active and passive conditions.
E. The passive tension is only produced by the attached myosin heads.
Answer (2)
The correct claim regarding the relation of tension/length in skeletal muscle fibers is A, which states that passive tension is always present under appropriate muscle length conditions. This highlights that passive tension occurs even in active and passive states due to elastic properties. Active tension involves myosin and actin interactions during contraction.
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In skeletal muscle fibers, understanding the relationship between tension and length is crucial for comprehending muscle mechanics. Let's explore the concepts:
Passive Tension : This is the tension developed in a muscle when it is stretched, even when the muscle is not actively contracting. It arises from the elastic properties of the muscle tissue itself, including the connective tissues and other structural components. Therefore, passive tension is indeed present in both active and passive conditions. Thus, the claim 'The passive tension is always present, in active and passive conditions' is correct.
Active Tension : This occurs when the muscle actually contracts. It's generated by the sliding of the myofilament cross-bridges of actin and myosin during muscle contractions, consuming energy in the form of ATP.
Total Tension : This is the sum of both active and passive tensions. When a muscle is activated (contracts), total tension measures the active force generated by engaged cross-bridges, in addition to any passive tension.
From the options provided, you can eliminate choices that mention passive tension being produced solely by attached myosin heads since passive tension does not involve active cross-bridge attachment.
To sum up, the correct option based on the information provided is: 'The passive tension is always present, in active and passive conditions.'
This explanation should help in understanding the basic mechanics of muscle tension and how they relate to muscle length in skeletal muscles.
