Ultrafiltration

• What process allows small molecules to be filtered from blood into the Bowman's capsule?

  Ultra filtration
• What is the main waste molecule filtered during ultra filtration?

  Urea
• What happens to useful molecules like glucose during ultra filtration?

  They are filtered out of the blood
• How many nephrons does each kidney contain approximately?

  1.5 million
• What is the role of the proximal convoluted tubule in the nephron?

  To return useful molecules to the blood
• What is the name of the blood vessel that brings blood into the glomerulus?

  Afferent arteriole
• Why is blood pressure higher in the glomerulus?

  Because of the larger lumen of the afferent arteriole
• What is hydrostatic pressure in the context of the nephron?

  Pressure that forces small molecules out of blood
• What types of molecules are forced into the Bowman's capsule during ultra filtration?

  Water, urea, glucose, amino acids
• What cannot pass through the Bowman's capsule during ultra filtration?

  Blood cells and large plasma proteins
• What specialized cells are found in the Bowman's capsule?

  Podocytes
• What is the function of the gaps between the endothelial cells of the capillary?

  To allow small molecules to leave the blood
• What is the basement membrane's role in ultra filtration?

  It acts as a filter for small molecules
• What are pedicels in the context of podocytes?

  Extensions that wrap around capillaries
• What is the composition of the fluid in the Bowman's capsule after ultra filtration?

  Contains water, urea, glucose, amino acids
• What happens to glucose and amino acids after ultra filtration?

  They are reabsorbed back into the blood
• What are the key steps in the process of ultra filtration in the nephron?

  • Blood enters the glomerulus via the afferent arteriole.
  • High hydrostatic pressure forces small molecules into the Bowman's capsule.
  • Small molecules include urea, water, glucose, amino acids, vitamins, and mineral ions.
  • Blood cells and large proteins remain in the blood.
• What adaptations of the nephron facilitate ultra filtration?

  • Afferent arteriole has a larger lumen than the efferent arteriole.
  • Gaps between endothelial cells allow small molecules to pass.
  • Basement membrane filters out large molecules.
  • Podocytes with pedicels create gaps for small molecules.
• What is the difference between ultra filtration and selective reabsorption in the nephron?

  • Ultra filtration: filtering small molecules into Bowman's capsule.
  • Selective reabsorption: returning useful molecules to the blood.