what are the mechanism of muscular system?

Answer 1

The Mechanism of Muscular contraction. Muscle contraction reduces the length of each sarcomere. The sliding filament theory is explained below.
The thin filaments ratchet across thick filaments to pull the Z lines together and shorten the sarcomere. The myofilaments themselves do not contract.
Myosin molecules on thick filaments attach to the actin on the thin filaments to form a crossbridge. The cross bridges then bend inward pulling the thin filament toward the center of the sarcomere. These cross bridges are broken and reformed further down .
Energy for cross bridge formation comes from the hydrolysis of ATP by the head region of the myosin.
Skeletal muscle contracts when stimulated by motor neurons.
Graded Contraction of Whole Muscles. are due to summation of multiple motor unit activity and wave summation.
Motor neurons usually deliver their stimuli rapidly, resulting in a smooth contraction.
A motor unit consist of a single motor neuron and all the muscle fibers it controls.
As more motor neurons are recruited by the brain, tension in the muscle progressively increases.
Duration of the muscle contraction depends on how long the concentration of calcium remains elevated.
Slow fibers have longer lasting twitches because they have less sarcoplasmic reticulum. The calcium remains in the cytoplasm longer. They have many mitochondria, rich blood supply, and myoglobin.
Fast fibers have short duration twitches and found in fast muscles for rapid, powerful contractions.

Answer 2

Pulleys for the action

Actin and myosin for the contraction.

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Answer 3

Kiteen(sp) makes muscles contract.