Human Physiology Lecture Notes

Difference between Primary and Secondary Myofilaments – Comparison Table


primary vs secondary myofilaments

Primary Myofilaments vs Secondary Myofilaments
(Difference between the Primary Myofilaments and Secondary Myofilaments of Myofibrils)

Myofilaments are the filaments of myofibrils (myofibrils are the basic structural unit of muscle cells). The myofilaments are composed of proteins particularly actin and myosin. The detailed structural analysis shows that the muscle sarcomere composed of bundles of two types of myofilaments called primary myofilaments and secondary myofilaments. The present post discusses the difference between the Primary Myofilaments and Secondary Myofilaments with a comparison table.

Learn more: Difference between A-Band and I-Band

Difference between Primary and Secondary Myofilaments

Continue reading

Human Physiology Lecture Notes

Difference between A-Band and I-Band of Sarcomere – Comparison Tab


A-band vs I-band

A-Band vs I-Band
Difference between A-Band and I-Band of a Sarcomere

The basic structural and functional unit of a striated muscle is called the Sarcomere. The sarcomere is the repeating units of a striated muscle occur between two Z-lines. This gives the striated appearance of the skeletal or cardiac muscles. The sarcomere composed of myofibrils, an array elongated contractile protein threads found in striated muscle cells. There are two types of myofibrils in the sarcomere called thin filaments and thick filaments. The thin filaments are made of protein called Actin and the thick filaments are made of proteins called Myosin. The actin and myosin filaments in a sarcomere are arranged in a specific manner so that their overlapping and interlocking patterns produce distinct bands when they are observed under a microscope. These bands are technically called as A-bands (Anisotropic) and I-Bands (Isotropic). The present post discusses the Difference between A-bands and I-bands with a comparison table.

Sarcomere diagram

Structure of Sarcomere (Source: Wikipedia)

Continue reading