Which step in urine formation occurs as molecules and ions are both passively and actively moved from the nephron into the blood of the peritubular capillary network?
A) glomerular filtration
B) tubular reabsorption
C) creatinine production
D) tubular secretion
E) filtration of small molecules into glomerular filtrate

Question

Quizplus · Accepted Answer

Tubular reabsorption occurs as molecules and ions are both passively and actively moved from the nephron into the blood of the peritubular capillary network. Glomerular filtration is the first step in urine formation, where small molecules are filtered out of the blood and into the glomerular filtrate. Creatinine production is not a step in urine formation, but rather a waste product of muscle metabolism that is excreted in urine. Tubular secretion is the opposite of reabsorption, where substances are actively secreted from the blood into the nephron to be excreted in urine. Filtration of small molecules into glomerular filtrate also occurs during the initial step of glomerular filtration.

Which Step in Urine Formation Occurs as Molecules and Ions