Physio 05: Excitable Tissue: Muscle

Muscle is where physiology stops talking and starts doing.In this episode, Medlock Holmes turns his attention from signal transmission to signal execution. We explore how electrical excitation is transformed into contraction across skeletal, cardiac, and smooth muscle—each obeying the same fundamental principles, yet adapted for very different physiological roles.Rather than memorising fibre types or contraction curves, this episode focuses on the logic of excitation–contraction coupling: how calcium acts as a decisive messenger, how actin and myosin generate force through cyclical interaction, and how structural organisation determines speed, strength, and endurance.Muscle is not simply tissue that contracts.It is tissue that responds with purpose—sometimes rapidly, sometimes rhythmically, sometimes quietly and continuously.Key Takeaways* Muscle converts electrical signals into mechanical work* Calcium is the central regulator of contraction across all muscle types* Skeletal, cardiac, and smooth muscle share core mechanisms but differ in control* Force generation depends on sarcomere structure and filament overlap* Muscle performance reflects physiological role, not just strength This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe