Kidney Structure and Function

• What is the functional unit of the kidney?

  The nephron
• How many nephrons does each kidney contain approximately?

  Around one million nephrons
• What is the primary role of nephrons?

  To filter blood and produce urine
• What small molecules are absorbed during the initial filtration in the nephron?

  Water, glucose, amino acids, and urea
• What is the name of the process where small molecules are absorbed from the blood into the kidney tubules?

  Filtration
• Which substances are not filtered out of the blood during kidney filtration?

  Large molecules like proteins and blood cells
• Why aren’t proteins and blood cells filtered into the nephron?

  They are too large to pass through the filtering membrane
• What is the process called where useful substances are taken back into the blood after filtration?

  Selective reabsorption
• Which important molecule is always reabsorbed into the blood during selective reabsorption?

  Glucose
• What happens to waste substances like urea after filtration and selective reabsorption?

  They remain in the tubule and are excreted in urine
• What analogy can be used to describe the nephron’s function?

  • Like cleaning a house
  • Removing everything first
  • Keeping only what’s useful
  • Discarding the rest
• What is the final product that leaves the nephron after filtration and reabsorption?

  Urine
• What does urine contain?

  Waste products such as urea, excess ions, and water
• Where is urine transported after it is formed in the kidneys?

  It flows through the ureters to the bladder