Substances are said to be what when they move from the tubular fluid back into the blood?

• A. Filtered
• B. Reabsorbed
• C. Secreted
• D. Excreted

Answer: (B)

Verified step by step guidance

1. Step 1: Begin by understanding the key terms provided in the problem. 'Filtered' refers to substances that pass from the blood into the tubular fluid during the process of filtration in the kidneys. 'Reabsorbed' refers to substances that move from the tubular fluid back into the blood. 'Secreted' refers to substances actively transported from the blood into the tubular fluid. 'Excreted' refers to substances that are eliminated from the body in urine.
2. Step 2: Focus on the phrase 'move from the tubular fluid back into the blood.' This describes the process of reabsorption, where useful substances like water, glucose, and ions are reclaimed by the body from the filtrate.
3. Step 3: Recall the physiological process of reabsorption in the nephron. This occurs primarily in the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct, where substances are transported back into the bloodstream.
4. Step 4: Eliminate the other options based on their definitions. 'Filtered' describes the initial movement of substances into the tubular fluid, not back into the blood. 'Secreted' involves movement into the tubular fluid, and 'Excreted' refers to substances leaving the body in urine.
5. Step 5: Conclude that the correct term for substances moving from the tubular fluid back into the blood is 'Reabsorbed,' as this matches the physiological process described.