Controlling Blood Glucose

• What is the main function of the nephron?

  To filter blood and create urine
• Where does filtering and osmoregulation occur in the kidney?

  In the nephrons
• How many nephrons are there in each kidney?

  About 1 million
• What are the main parts of the nephron?

  • Renal capsule (Bowman's capsule)
  • Proximal convoluted tubule (PCT)
  • Loop of Henle
  • Distal convoluted tubule (DCT)
  • Collecting duct
• What is the role of the renal capsule?

  To enclose the glomerulus for filtration
• What happens during ultrafiltration?

  Water and small molecules are filtered out
• What is the filtrate called after ultrafiltration?

  Glomerular filtrate
• Why are proteins and blood cells not found in urine?

  They are too large to be filtered out
• How is glucose reabsorbed in the nephron?

  By active transport in the PCT
• What percentage of filtrate is reabsorbed in the PCT?

  85%
• What are the adaptations of PCT cells for reabsorption?

  • Microvilli for increased surface area
  • Numerous mitochondria for energy
• What is the role of the loop of Henle?

  To maintain sodium ion concentration gradient
• What are the two limbs of the loop of Henle?

  Ascending limb and descending limb
• Why is the ascending limb impermeable to water?

  It has thick walls
• How does water move out of the descending limb?

  By osmosis into the interstitial space
• What happens to sodium ions in the ascending limb?

  They are actively transported out
• What is the effect of a longer loop of Henle in desert animals?

  More water is reabsorbed
• What is the overall process of urine formation in the nephron?

  1. Ultrafiltration in the renal capsule
  2. Selective reabsorption in the PCT
  3. Sodium ion gradient maintenance in the loop of Henle
  4. Further reabsorption in the DCT and collecting duct
  5. Formation of urine
• What is the final product of the nephron's function?

  Urine
• What changes the permeability of the DCT and collecting duct?

  Amount of water in the blood
• Where can students find practice questions related to this topic?

  On Miss Estri's platform
• What is the importance of reabsorption in the kidneys?

  To retain useful substances in the blood
• How does the nephron contribute to homeostasis?

  By regulating water and solute balance