Final answer:
Acids activate receptors that correspond to sour tastes on the tongue, causing an increase in hydrogen ion concentration and depolarization of taste neurons.
Step-by-step explanation:
Acids primarily activate receptors that respond to sour tastes. Sour tastants belong to the thermoreceptor protein family. These sour tastants are usually acids, which, when they bind to the receptors, trigger a change in the ion channels. These changes increase hydrogen ion (H+) concentrations in the taste neurons, thus causing depolarization. Taste receptors on the tongue can detect five primary tastes: sweet, sour, bitter, salty, and umami. However, only sour tastes are specifically associated with acid activation. Unlike sour and salty tastes that involve direct ion channel interactions, sweet, bitter, and umami tastes rely on G-protein coupled receptors for detection.