ELECTRICAL SIGNALS AMONG CELLS

Neurology

The document explains how voltage‑gated Na+ and K+ channels generate and shape the action potential, describing absolute and relative refractory periods. It details the steps of chemical synaptic transmission, from vesicle loading to neurotransmitter release and receptor activation. The neuromuscular junction is highlighted, showing how acetylcholine activates nicotinic receptors to trigger an end‑plate potential and subsequent calcium‑dependent muscle contraction. Finally, the excitation‑contraction coupling cascade, involving troponin, tropomyosin, and the actin‑myosin cross‑bridge cycle, is outlined.