Shared gustatory sensor for acids and ammonium

Gustation is a chemical sense that, along with olfaction (smell), contributes to our perception of taste. It starts with the activation of receptors by chemical compounds (tastants) dissolved in the saliva. The saliva and filiform papillae on the tongue distribute the tastants and increase their exposure to the taste receptors.

The perception of a salty flavor is facilitated by sodium ions within the oral salivary fluid. Upon consumption of a salty substance, salt crystals disassemble, leading to the liberation of its constituents—Na+ and Cl- ions. These ions subsequently dissolve into the salivary fluid present in the oral cavity. The external environment of the gustatory cells experiences an elevation in Na+ concentration, thereby establishing a potent concentration gradient. This gradient propels the...

Gustation, or the sense of taste, is intrinsically linked to the anatomical structures located on the tongue. This organ's surface, along with the entirety of the oral cavity, is adorned with stratified squamous epithelium. Evident on the tongue are elevated structures known as papillae (singular = papilla), which house the mechanisms for the transduction of gustatory stimuli. Four distinct types of papillae exist, each identified by their unique morphological attributes: the circumvallate,...

The titration curve of a weak base like ammonia with a strong acid like hydrochloric acid is the mirror image of the titration curve of a weak acid with a strong base.
Using the ICE table and substituting the Kb value, we calculate the initial pH of 50 mL of 0.1 M ammonia to be 11.11. Addition of 25 mL of 0.1 M hydrochloric acid to this solution of ammonia results in a buffer with an equal concentration of ammonia and ammonium ions. The pH of this buffer can be calculated by substituting these...

In 1923, the Brønsted–Lowry definition of acids and bases was proposed by Johannes Brønsted and Thomas Lowry. According to this theory, a Brønsted acid is defined as a species that donates a proton in a chemical reaction and gets converted to its conjugate base. A Brønsted base is defined as a species that accepts a proton in a chemical reaction and gets converted into its conjugate acid. These transfers of protons are caused by the displacement of electrons in these reactions, which is...

The human body carefully regulates the internal pH of different organs to maintain homeostasis. For example, while the blood plasma maintains a neutral pH of 7, the stomach lumen has an acidic pH of 1.5 - 3.5. The low pH of stomach lumen helps kill pathogens in the food and break down complex food molecules.
The acid-secreting gastric mucosal epithelial cells (parietal cells) lining the stomach lumen maintain the low pH in the lumen. Numerous ion transporters and channels on these parietal...