Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Thick filaments are protein structures in muscle cells composed primarily of myosin. They interact with thin filaments during muscle contraction to produce force and movement.
5 Must Know Facts For Your Next Test
Thick filaments are primarily made up of the protein myosin.
Each thick filament is surrounded by six thin filaments in a hexagonal arrangement.
The heads of myosin molecules on thick filaments form cross-bridges with actin in thin filaments during muscle contraction.
Thick filaments are located in the A-band of the sarcomere, contributing to its dark appearance under a microscope.
ATP binding and hydrolysis on myosin heads provide the energy necessary for muscle contraction.
Review Questions
Related terms
Thin Filaments: Composed mainly of actin, these structures interact with thick filaments for muscle contraction.
Sarcomere: The basic functional unit of striated muscle fibers responsible for muscle contraction.
Myofibril: A long, filamentous organelle within muscle cells containing repeating units of sarcomeres.