6.5k views
2 votes
More cytosolic Ca2+ leads to more exposed myosin binding sites, leads to more cross-bridges forming, leads to higher contractile force of that particular fiber:

A) Positive feedback loop

B) Negative feedback loop

C) Feedforward regulation

D) Homeostatic regulation

User Ian Ross
by
8.1k points

1 Answer

2 votes

Final answer:

The increase in cytosolic Ca2+ which leads to more myosin binding and higher contractile force is an example of a positive feedback loop. It is part of the excitation-contraction coupling mechanism in muscle fibers, relying on calcium ion release from the sarcoplasmic reticulum.

Step-by-step explanation:

The process described as increasing cytosolic Ca2+ leading to more exposed myosin binding sites, more cross-bridges forming, and as a result, a higher contractile force of a muscle fiber, aligns with the concept of positive feedback loop in physiological systems. In this loop, the initial stimulus (more Ca2+ in the cytosol) is amplified to produce a larger effect (increased muscle contraction), which in turn promotes more of the stimulus (further Ca2+ release).

This mechanism is part of excitation-contraction coupling in muscle fibers, where the sarcolemma must be excited to trigger an action potential which is then coupled to muscle contraction via calcium ions (Ca2+) release from the sarcoplasmic reticulum (SR). The released Ca2+ ions interact with troponin and tropomyosin on the actin filaments, leading to the formation of cross-bridges between actin and myosin, ultimately resulting in muscle fiber contraction.

User Yuan JI
by
7.7k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories