The surface of the tongue is covered with

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and has bumps called

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stratified squamous epithelium, where many taste buds can be found.

A. More carbonic acid is formed: The bicarbonate ion (HCO₃⁻) binds with H⁺ from HCl, forming carbonic acid (H₂CO₃), which helps buffer the drop in pH.
B. Hydrochloric acid is neutralized by sodium hydroxide: Sodium hydroxide is not involved in this buffer system; this describes a basic chemical reaction, not physiological buffering.
C. Carbonic acid is converted into bicarbonate: The reverse happens when acid is added-bicarbonate becomes carbonic acid.
D. The blood plasma pH is reduced: The buffer system prevents a large drop in pH by neutralizing the added acid.

A. Buffered hydrogen ions are excreted in urine: This process allows new bicarbonate ions to enter the plasma, helping correct acidosis.
B. Glutamine is metabolized by deamination, oxidation, and acidification: Glutamine metabolism in renal tubule cells generates ammonia and bicarbonate, contributing to acid-base balance.
C. Ammonium ions are excreted in urine: Excreting ammonium (NH₄⁺) removes H⁺ from the body and indirectly adds new bicarbonate to the plasma.
D. Bicarbonate ions are reclaimed by tubular reabsorption: This does not generate new bicarbonate-it simply prevents loss of existing bicarbonate, which is important but not a replenishing mechanism during depletion.