When blood passes by the _______, nitrate from the blood is actively concentrated to mM levels into _______.

When blood passes by the _______, nitrate from the blood is actively concentrated to mM levels into _______.

• A. Salivary glands; Saliva
• B. Kidneys; Urine
• C. Pancreas; Pancreatic juice
• D. Liver; Bile

Answer: (A)

Nitrate in the bloodstream is actively taken up by the salivary glands and secreted into saliva, where it becomes concentrated to millimolar levels. This active transport into saliva creates a high nitrate reservoir that oral bacteria can exploit. Those bacteria reduce nitrate in saliva to nitrite, contributing to the oral nitrite pool and influencing both microbial ecology and nitric oxide biology in the mouth and beyond. The reason this fits is that the salivary glands are specialized for concentrating certain circulating ions into saliva, a process not shared by the pancreas or liver, which secrete digestive fluids, or by the kidneys in the context described. Hence, saliva is the fluid into which blood-borne nitrate is actively concentrated.

Nitrate in the bloodstream is actively taken up by the salivary glands and secreted into saliva, where it becomes concentrated to millimolar levels. This active transport into saliva creates a high nitrate reservoir that oral bacteria can exploit. Those bacteria reduce nitrate in saliva to nitrite, contributing to the oral nitrite pool and influencing both microbial ecology and nitric oxide biology in the mouth and beyond.

The reason this fits is that the salivary glands are specialized for concentrating certain circulating ions into saliva, a process not shared by the pancreas or liver, which secrete digestive fluids, or by the kidneys in the context described. Hence, saliva is the fluid into which blood-borne nitrate is actively concentrated.