Tubular Reabsorption and Secretion
Start with the big picture
Tubular reabsorption moves substances from the nephron tubule toward the blood, whereas secretion moves substances from the blood into the tubule. The proximal convoluted tubule performs bulk recovery, including glucose, amino acids, and much of the filtered sodium, water, and bicarbonate. Along the loop of Henle, the descending limb permits water movement, while the thick ascending limb reabsorbs sodium, potassium, and chloride without water, helping dilute tubular fluid. The distal tubule and collecting duct make further adjustments: principal cells respond to aldosterone and ADH, and intercalated cells contribute to acid–base regulation. The lesson also introduces transport maximum and threshold effects, using glucose reabsorption and glycosuria as a clinical connection.
What you'll learn
- Distinguish tubular reabsorption from tubular secretion.
- Describe the major reabsorptive roles of the proximal convoluted tubule.
- Compare water and solute handling in the descending and thick ascending limbs.
- Explain how distal nephron cells contribute to salt, water, potassium, and acid–base regulation.
- Relate transport maximum and threshold effects to glucose excretion.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
