Name: Rheumatoid Arthritis
Uploaded: 2019-07-19
Duration: 6 min 51 s
Description: Rheumatoid arthritis is an autoimmune disease in which your immune system attacks healthy cells in your body by mistake. Let's learn more about this autoimmu...

Question

Describe the important steps in muscle contraction.

Accepted Answer

Muscle tissue contains some fibers called muscle fibers, which consist of a single muscle cell. They are made up of actin and myosin. They help to control the physical forces within the body. There are three types of muscle tissues that are divided on the basis of their function.

Skeletal muscle: Attached to the skeleton by tendons and control the voluntary movements of the body.

Smooth muscle: Smooth muscles are involuntary, meaning that you can’t control them. They’re found in your internal organs and eyes.

Cardiac muscle: These are the muscles that are found in the heart.

The most widely accepted theory explaining how muscle fibers contract is called the sliding filament theory. According to this theory, myosin filaments use energy from ATP to “walk” along the actin filaments with their cross bridges. This pulls the actin filaments closer together. The movement of the actin filaments also pulls the Z lines closer together, thus shortening the sarcomere.

The following are the biochemical events in the mechanism of muscle contraction :

The active site on actin is exposed as Ca++ binds troponin.

The myosin head forms a cross-bridge with actin.

During the power stroke, the myosin head bends and ADP and phosphate are released.

A new molecule of ATP attaches to the myosin head, causing the cross-bridge to detach.

ATP hydrolyzes to ADP and phosphate which returns the myosin to the cocked position.

Describe the important steps in muscle contraction.

Important Questions on Musculo-Skeletal System

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