ANATOMY

Detailed explanation-1: -An A-band contains the entire length of a single thick filament . The anisotropic band contains both thick and thin filaments. Within the A-band is a paler region called the H-zone (from the German “heller", brighter). Named for their lighter appearance under a polarization microscope.

Detailed explanation-2: -Each sarcomere consists of a central A-band (thick filaments) and two halves of the I-band (thin filaments). The I-band from two adjacent sarcomeres meets at the Z-line. The central portion of the A-band is the M-line, which does not contain actin.

Detailed explanation-3: -By modifying the thick filament assembly conditions, we vary the average lengths of SMM thick filaments from 0.2 to 1.2 m (Table 2, Fig S3). Using the known linear density of myosin heads, this results in thick filaments where the number of motor heads N ¯ h e a d s varies from ∼100 to ∼600.

Detailed explanation-4: -Definition: The A band is the region of a striated muscle sarcomere that contains myosin thick filaments. In fact, the A band is the entire length of the thick filament of the sarcomere.

Detailed explanation-5: -The I-band consists of actin filaments that are not overlapped by myosin; this region contains the Z-disc. The A-band marks the length of an entire thick filament (myosin), including the overlap region with actin.