Structure nephron

• What is the structural and functional unit of the kidney?

  Nephron
• How many nephrons do dogs have per kidney?

  400,000
• How many nephrons do cats have per kidney?

  200,000
• How can nephrons be classified based on the location of their glomeruli?

  Superficial, midcortical, juxtamedullary
• What are the two classifications of nephrons based on the length of their loop of Henle?

  Short-looped and long-looped
• Which species have only long-looped nephrons?

  Cats, dogs, arid climate species
• What type of nephrons do beavers have?

  Short-looped nephrons
• What is the diameter of a horse's renal corpuscle?

  220 µm
• What is the diameter of a cat's renal corpuscle?

  120 µm
• What is the vascular pole of the renal corpuscle?

  Where blood vessels enter and exit
• What is the urinary pole of the renal corpuscle?

  Where the glomerular capsule opens into the proximal tubule
• What is Bowman's space?

  Intra-corpuscular space in the renal corpuscle
• What is the structure of the glomerular capillary tuft?

  A network of branching and anastomosing capillaries
• What is the nature of the filtration barrier in the glomerulus?

  Fenestrated endothelium and thick basement membrane
• What is the diameter range of pores in the capillary walls?

  50-150 nm
• What is the composition of the glomerular basement membrane?

  Three layers with collagen, proteoglycans, glycoproteins
• How does blood enter and leave the glomerulus?

  Enters via afferent arteriole, leaves via efferent arteriole
• What does the presence of blood or high protein levels in urine indicate?

  Damage to the filtration barrier
• What are podocyte processes and their function?

  Interlaced over capillaries, form filtration slits
• What is the role of the mesangium in the glomerulus?

  Core of the glomerulus with contractile cells
• What is another name for the glomerular capsule?

  Bowman's capsule
• What is the urinary space in the renal corpuscle?

  Space between visceral and parietal layers
• What is the structure of the parietal layer of the glomerular capsule?

  Thin simple squamous epithelium resting on basal lamina
• How does urine production begin?

  As an ultrafiltrate of blood in Bowman's space
• What happens to formed elements and larger soluble elements during urine production?

  They are removed during filtration
• What drives urine through the nephron?

  Pressure of continuing filtration
• What varies the concentration and composition of final urine?

  What needs to be cleared and water availability
• What is the structure of podocytes?

  Specialized epithelium with long foot processes
• What are filtration slits in podocytes?

  Narrow spaces between foot processes bridged by diaphragm
• What is the role of the brush border in the proximal tubule?

  Increases surface area for absorptive activity
• What happens to the proximal tubule when blood pressure drops?

  It collapses due to loss of hydrostatic pressure
• What type of epithelium is found in the loop of Henle?

  Simple squamous epithelium
• What is the significance of the loop of Henle in urine concentration?

  Allows urine to be hypertonic to body fluids
• What are the main components of the nephron?

  • Renal corpuscle
  • Glomerulus
  • Glomerular capsule (Bowman's capsule)
  • Proximal tubule
  • Thin limbs of Henle’s loop
  • Thick ascending limb of Henle’s loop
  • Distal convoluted tubule
  • Connecting segment
• What is the process of urine production in the nephron?

  1. Filtration of blood in Bowman's space
  2. Modification of filtrate through nephron segments
  3. Final urine composition varies based on needs
  4. Urine drains through excretory passages
• What are the functions of the mesangial cells?

  • Form the core of the glomerulus
  • Contain contractile proteins
  • Act as resident macrophages
  • Remove protein aggregates from the glomerular filter
• What is the filtration mechanism in the glomerulus?

  • Blood enters under pressure
  • Fenestrated endothelium allows plasma to pass
  • Formed elements and large proteins are retained
  • Filtrate moves into Bowman's space
• What is the role of podocytes in the filtration barrier?

  • Form filtration slits between foot processes
  • Cover capillary surface
  • Create a meshwork for filtration
  • Prevent large molecules from passing
• What are the characteristics of the proximal tubule?

  • Begins at the urinary pole
  • Contains proximal convoluted tubule and proximal straight tubule
  • Has a brush border for absorption
  • Recovers 99% of filtrate components
• What are the segments of the loop of Henle?

  • Descending thick limb
  • Descending thin limb
  • Ascending thin limb
  • Thick ascending limb