How urine is formed

Urine is formed within the nephron using three major processes:

1. glomerular filtrationion

   • Blood enters through afferent arteriole

   • Fluid and solutes from the blood pass through specialized filtration cells called podocytes into the Bowman’s capsule

   • Once in the capsule, the fluid is called filtrate

   • The remaining blood leaves through the efferent arteriole away, and the filtrate continues into the renal tubule

2. Tubular reabsorption

   • Most of the water (80%) and many ions and nutrients are reabsorbed into the blood through both passive and active transport

   • This occurs mostly in the proximal convoluted tubule

3. Tubular secretion

   • Additional substances are actively removed from the blood (drugs, steroids,etc)

   • Hydrogen (H+) and potassium (K+) are fine tuned to control blood pH