L21 - Kidney and nephron

• What are the main components of the urinary system?

  Two kidneys, two ureters, one bladder, one urethra
• What is the primary function of the kidneys?

  To filter blood and produce urine
• What do the ureters do?

  Transport urine from kidneys to bladder
• What is the role of the urinary bladder?

  Temporary storage reservoir for urine
• What is the function of the urethra?

  Transports urine out of the body
• What are the waste products excreted by the kidneys?

  Urea, ammonia, creatinine, uric acid, urobilin
• How do kidneys regulate blood ion, pH, and osmolarity?

  By filtering and reabsorbing substances
• What hormone do kidneys produce?

  Erythropoietin
• How do kidneys regulate blood volume and pressure?

  By adjusting urine output and blood flow
• What is the renal hilum?

  Indentation along the kidney's concave border
• What are the three distinct regions of the kidney?

  Renal cortex, renal medulla, renal pelvis
• What is the function of the renal pelvis?

  Funnel-shaped tube continuous with ureter
• What do minor and major calyces do?

  Collect urine and empty it into renal pelvis
• How does blood enter each kidney?

  Through one renal artery
• What are afferent arterioles responsible for?

  Giving rise to microscopic vasculature in kidneys
• How do veins relate to renal arterial circulation?

  They trace the renal arterial circulation in reverse
• What is the renal nerve plexus primarily composed of?

  Mostly sympathetic fibers
• What do the sympathetic fibers in the renal nerve plexus regulate?

  Renal blood flow and urine formation
• What is the primary function of nephrons?

  To form urine
• How many nephrons are there per kidney?

  More than 1 million
• What do nephrons recover from blood?

  Chemicals the body needs
• What do nephrons secrete?

  Selected chemicals to eliminate
• What are the two main parts of a nephron?

  Renal corpuscle and renal tubules
• Where is the renal corpuscle located?

  In the renal cortex
• What is the function of renal tubules?

  Filtrate regulation through absorption and secretion
• What is the glomerulus?

  A network of fenestrated capillaries
• How do fenestrated capillaries in the glomerulus function?

  Increase permeability for filtrate formation
• What maintains high pressure in the glomerulus?

  Afferent and efferent arterioles
• What are the two layers of the glomerular (Bowman’s) capsule?

  Parietal layer and visceral layer
• What is the role of podocytes in the visceral layer?

  Allow filtrate to pass into the capsule space
• What is the path of filtrate through the nephron?

  From renal corpuscle to renal tubules
• What is unique about the histology of renal tubules?

  Each region has a unique histology
• What is the function of the proximal convoluted tubule (PCT)?

  Absorption and secretion with dense microvilli
• What are the characteristics of the nephron loop (Loop of Henle)?

  Thin descending limb and ascending limb
• What is the function of the distal convoluted tubule (DCT)?

  Similar to PCT but lacks microvilli
• What do principal cells in collecting ducts control?

  H2O and Na+ balance
• What do intercalated cells in collecting ducts regulate?

  pH by secreting/absorbing H+ or HCO3-
• How do collecting ducts function in urine collection?

  Collect filtrate from many nephrons
• What is the appearance of renal pyramids due to?

  Striped appearance from collecting ducts
• What percentage of nephrons are cortical nephrons?

  85%