Question

a patient has strange disorder in which both myosin and actin do not attach to the z-disk. Discuss the structure of the sarcomere and whether this disorder will influence the development of muscle tension.

Answer 1

Sarcomere is the component of the striated muscle and makes up the the skeletal muscles. Sarcomeres helps in the initiation of voluntary movement of muscles as well as in muscle contraction.

The end of sarcomere is decorated by Z disc and within sarcomere the dark band structure alternates with light bands.The dark band represents the anisotropic band named as A band whereas light band represnts the isotropic band named as I band. The I band contains the thin actin filaments and A band has myosin thick band. The actin and myosin tend to slide over each other (muscle contraction occur) and makes the middle region where only myosin is available and in peripheral region of A band.The actin filaments gets attached to the + end of the Z disc which include the actin crosslinking protein known as alpha actinin and myosin remains attached to the middle line (M region) of sarcomere.

Disorder where myosin and actin don't attach to the Z-disc may result into defective muscle tension. As Actin get attached to Z-disc via actin crosslinking protein generate the effiecient muscle contraction and tension.The Z disc is the site of polarity reversal for actin which is essential for bipolar myosin to interact in successive sarcomere to facilitate the muscle contraction.