Question

practice it
what is tubular secretion?
the process of transporting substances from the urine into the blood for reabsorption.
the process of transporting substances from the blood into the urine for elimination.
the process of transporting substances from the filtrate into the urine for elimination.
the process of transporting substances from the blood into the filtrate for elimination.
the process of transporting substances from the filtrate into the blood for reabsorption.

Explanation:

Tubular secretion is a process in the nephron (the functional unit of the kidney). In this process, substances (such as certain ions, drugs, and waste products) are actively transported from the peritubular capillary blood (the blood vessels around the renal tubules) into the tubular fluid (the filtrate within the renal tubules). This helps in the elimination of these substances from the body. For example, hydrogen ions (\(H^+\)) are secreted to regulate the pH of the blood. Another example is the secretion of creatinine (a waste product) and some drugs.

Answer:

The process of transporting substances from the blood into the filtrate for elimination.