MEDICAL BIOLOGY, HUMAN ANATOMY, PHYSIOLOGY AND PATHOLOGY - Y.I. Fedoniuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

CHAPTER 8. URINATION PROCESS AND ITS PATHOLOGY

ANATOMY AND PHYSIOLOGY OF THE URINARY ORGANS

MECHANISM OF URINE FORMATION

2. REABSORPTION

The reabsorption of various substances from the primary urine back into the Blood is called reabsorption, which takes place in the nephron tubules. This applies to substances such as Water, glucose, Amino Acids, and salts.

Due to reabsorption, out of 180 L of primary urine, only 1-1.5 L of secondary urine remains and is excreted from the body.

Reabsorption is mediated by active and passive transport. Passive transport occurs along electrochemical, concentration, and osmotic gradients.

In this way, water, carbon dioxide, certain ions, and a small amount of urea return to the bloodstream.

Active Transport occurs against electrochemical and concentration gradients. This process requires ATP energy, special carrier Proteins, and Na+ ions bound to them. Glucose, amino acids, and Na+ are actively transported.



Last update: 08/08/2026

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