Part 8/14:
Only found in the heart, cardiac muscles are involuntary but striated, equipped for rhythmic, continuous contractions vital for blood circulation. Their unique feature is the ability to generate rhythmic contractions myogenically, with modulation from autonomic nerves.
Molecular Basis of Muscle Contraction: The Sliding Filament Theory
The sliding filament model has been elucidated through advanced 3D imaging and molecular studies:
Myosin heads pivot during the power stroke, pulling actin filaments inward.
Cross-bridge formation is regulated by calcium ions released from the sarcoplasmic reticulum.
ATP binding and hydrolysis control attachment and detachment cycles.
This process is remarkably conserved across muscle types, from invertebrate worms to humans.