Isotropic bands

In physiology, isotropic bands (better known as I bands) are the lighter bands of skeletal muscle cells (a.k.a. muscle fibers). Isotropic bands contain only actin-containing thin filaments.[1] The thin filaments are placed between 2 myosin filaments and contain only the actin filaments of neighboring sarcomeres. Bisecting the I band and serving as an anchoring point for the two adjacent actin filaments is the Z disc. During muscle contraction, the I band will shorten, while an A band will maintain its width.[2]

The muscle is made up of several myofibrils packed into functional units surrounded by different layers of connective tissues (epimysium, perimysium, and endomysium). The main contractile unit is mainly composed of protein filaments (myofilaments), namely myosin (thick filaments) and actin (thin filaments).
  1. ^ Goldblum JR (2018). "Section 9: Bone and Soft Tissue Pathology, Chapter 41: Soft Tissues". In McKenney JK, Goldblum JR, Lamps LW, Myers JL (eds.). Rosai and Ackerman's Surgical Pathology (11 ed.). Elsevier. pp. 1810–1914.
  2. ^ "Z disk - definition - glossary". PhysiologyWeb. 2015.