Glomerular Filtration Process Quiz

Glomerular Filtration

• Urine is produced by filtering waste and fluids from the blood in the kidneys.
• The initial filtration occurs in the glomerulus through a process known as ultra-filtration.
• Glomerular filtrate primarily contains water, electrolytes, amino acids, bicarbonate, and nitrogenous wastes like urea, uric acid, and creatinine.
• Glomerular filtration rate (GFR) is influenced by hydrostatic pressure in the glomerulus, which is affected by the diameter difference of afferent and efferent arterioles.
• The kidney filters approximately 180 liters of blood daily, resulting in the production of 2.5 liters of urine under normal conditions.
• GFR is typically stable due to autoregulation, but can vary with changes in fluid intake or body fluid levels.

Selective Reabsorption

• The composition of glomerular filtrate differs from that of urine, indicating changes as fluid moves through the renal tubules (PCT, loop of Henle, DCT).
• For a healthy person, glucose is reabsorbed from the filtrate and is not found in urine, while urea and uric acid levels are higher in urine than in filtrate.
• Selective reabsorption allows for the recovery of specific molecules filtered out of blood, including nitrogenous wastes and water.
• Most selective reabsorption occurs in the proximal convoluted tubule (PCT), where vital substances are returned to the bloodstream.
• Around 67% of water, 100% of glucose, along with various electrolytes (Na, K, Cl, Ca, Mg, HPO42-) and nutrients are reabsorbed in the PCT.
• Water reabsorption is passive, while glucose and sodium reabsorption is active.
• Sodium aids in the reabsorption of negatively charged ions through charge interactions.
• Aldosterone hormone enhances sodium reabsorption, while antidiuretic hormone (ADH) promotes water reabsorption.