Sliding Filament Theory of Muscle Contraction
Sliding Filament theory describes the molecular changes that occur during muscle contraction at the sarcomere level, which is the basic functional unit of a muscle fiber.
- In the resting state, myosin heads are in a low-energy position, and the actin and myosin filaments do not overlap.
- When a motor neuron signals a muscle fiber to contract, an action potential is generated. It travels along the muscle cell membrane and into the muscle fiber through the transverse tubules.
- The action potential triggers the release of calcium ions from the sarcoplasmic reticulum.
- Calcium binds to troponin that results in change in shape of troponin. It allows tropomyosin to move away from the myosin-binding sites on actin.
- With the myosin-binding sites exposed, myosin heads can bind to actin, forming cross-bridges.
- The myosin heads undergo forceful contraction, pulling the thin actin filaments towards the center of the sarcomere.
- As myosin heads continue to cycle through binding, pulling, and releasing, the actin filaments slide past the myosin filaments, causing the sarcomere to shorten.
- When the action potential ceases and calcium ions are actively pumped back into the sarcoplasmic reticulum, the troponin-tropomyosin complex returns to its original position, blocking the myosin-binding sites on actin. This leads to muscle relaxation.
Sliding Filament Theory
The sliding filament theory explains how muscle fibres contract. The sliding filament theory can be best explained as how muscles contract by the interaction of actin and myosin filaments sliding past each other within muscle cells. The process requires ATP for energy.
The sliding filament theory was proposed in 1954 by Andrew Huxley and Rolf Niedergerke. In this article, we will study the sliding filament theory of muscle contraction notes in detail.
Table of Content
- What is Sliding Filament Theory?
- What is Sarcomere in Muscle?
- Sliding Filament Theory of Muscle Contraction
- Sliding Filament Theory Diagram
- Summary of the Sliding Filament Theory Steps
- How Does Muscle Contraction Occur?
- Importance of Sliding Filament Theory
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