Kidney

• What is the main function of the nephron?

  To filter blood and create urine
• Where does filtration 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 in the proximal convoluted tubule?

  Selective reabsorption of useful substances
• What is ultrafiltration?

  Filtration of blood under high pressure
• What substances are typically found in urine?

  Water, urea, and dissolved salts
• 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 is the role of the loop of Henle?

  To maintain sodium ion concentration gradient
• What happens in the ascending limb of the loop of Henle?

  It is impermeable to water and sodium ions are actively transported out
• What occurs in the descending limb of the loop of Henle?

  Water is reabsorbed by osmosis
• What is the significance of the sodium ion gradient in the loop of Henle?

  It enables water reabsorption into the blood
• What happens in the distal convoluted tubule (DCT)?

  Further reabsorption of water occurs
• What is the final step in urine formation?

  Remaining filtrate in the collecting duct forms urine
• How does the loop of Henle differ in desert animals compared to humans?

  • Desert animals have a longer loop of Henle
  • This allows for more sodium ions to be reabsorbed
  • More water is reabsorbed due to lower water potential
  • Results in concentrated urine for survival
• What is the importance of reabsorption in the kidneys?

  It prevents loss of essential substances
• What is the term for the process of taking substances back into the blood?

  Reabsorption
• What is the role of mitochondria in the proximal convoluted tubule?

  To provide energy for active transport
• What is the interstitial space in the nephron?

  The space between the nephron and capillaries
• How does the nephron contribute to homeostasis?

  By regulating water and electrolyte balance
• What happens to the filtrate as it moves through the nephron?

  It is progressively concentrated and modified
• What is the significance of the collecting duct in urine formation?

  It finalizes urine concentration before excretion
• What is the role of negative feedback in osmoregulation?

  It adjusts kidney function based on blood water levels
• What should never be found in urine of a healthy person?

  Proteins, blood cells, and glucose
• What is the function of the podocytes in the nephron?

  To provide an additional filtration layer
• What is the primary purpose of the nephron's structure?

  To maximize filtration and reabsorption efficiency
• How does the nephron adapt to varying hydration levels?

  By adjusting permeability of tubules