Which term describes the process in which substances are pulled back into the blood after waste products have been removed?

Reabsorption is the correct term to describe the process in which substances are pulled back into the blood after waste products have been removed. This process occurs primarily in the kidneys, specifically within the nephron, where valuable substances such as glucose, certain ions, and water are reclaimed from the tubular fluid and transferred back into the bloodstream. This is a crucial function that helps maintain the body's fluid and electrolyte balance, ensuring that essential nutrients are not lost in urine.

In contrast, excretion refers to the elimination of waste products from the body, which does not involve reclaiming substances for reuse. Filtration is the initial process in the kidneys where blood plasma is filtered through the glomerulus, separating waste from useful substances but not specifically reabsorbing them. Secretion is the process of actively transporting substances from the blood into the tubular fluid, which is different from reabsorption and focuses on the addition of waste products rather than their retrieval.