Name the four organs of the urinary system and state what each one does.
Walk through the three steps of urine formation in the nephron, in order.
Explain why the kidneys matter for fluid, electrolyte, and acid-base balance, not just for making urine.
What the lesson concludes
The urinary system is two kidneys, two ureters, one bladder, one urethra, and the nephron is the functional unit doing the work inside each kidney.
Urine forms in three steps: filtration at the glomerulus, reabsorption along the tubule, and secretion into the tubule.
The kidneys regulate blood volume, electrolyte balance, and blood pH, so a HESI question about the urinary system is often really a question about homeostasis.
Roughly one million nephrons per kidney means a large functional reserve, which is why kidney disease can be advanced before blood work shows it.