Calcium channels are specialized proteins found in the membranes of cells that allow the passage of calcium ions (Ca²⁺) into the cell. These channels play a crucial role in various physiological processes, including muscle contraction, neurotransmitter release, and hormone secretion. When activated, they open to let calcium ions flow in, which triggers specific cellular responses. There are different types of calcium channels, such as voltage-gated calcium channels and ligand-gated calcium channels. Each type responds to different signals, ensuring that calcium entry is tightly regulated. Proper functioning of these channels is essential for maintaining cellular health and overall body function.