Your tongue contains five types of actual taste receptors: sweet, salty, sour, bitter, and umami. Spiciness isn’t among them because it’s not a taste—it’s a pain response. Capsaicin molecules bind to TRPV1 receptors throughout your mouth, throat, and digestive system. These receptors normally detect actual heat and physical abrasion, sending urgent pain signals to your brain warning of potential tissue damage.