Skeletal muscle contraction

Muscle contraction and relaxation process

ATP is used during this phase and energy is released as heat. This can occur involuntarily e. During a concentric contraction, a muscle is stimulated to contract according to the sliding filament theory. This reaction results in the start of a contraction and the sliding filament theory. Figure 3. Smooth muscles can be divided into two subgroups: single-unit unitary and multi-unit. Aerobic respiration is the breakdown of glucose or other nutrients in the presence of oxygen O2 to produce carbon dioxide, water, and ATP. The enzyme at the binding site on myosin is called ATPase.

The myosin head moves toward the M line, pulling the actin along with it. Sarcomere Structure To understand the sliding filament model requires an understanding of sarcomere structure. This reaction is catalyzed by the enzyme creatine kinase and occurs very quickly; thus, creatine phosphate-derived ATP powers the first few seconds of muscle contraction.

Other actions such as locomotion, breathing, and chewing have a reflex aspect to them: the contractions can be initiated both consciously or unconsciously.

However, thick and thin filaments—the components of sarcomeres—do not shorten. If the muscle is stretched to a point the tension will increase in the muscle. This is an electrical event, called an action potential, that can be used as a cellular signal.

This zone where thin and thick filaments overlap is very important to muscle contraction, as it is the site where filament movement starts. When eccentric contractions are used in weight training, they are normally called negatives.

physiology of muscle contraction pdf

The breakdown of one glucose molecule produces two ATP and two molecules of pyruvic acid, which can be used in aerobic respiration or when oxygen levels are low, converted to lactic acid Figure 5 b.

On the other hand, when picking up a piano, the motor cortex signals all of the neurons in the biceps so that every myofiber participates.

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Muscle contraction