Renal system

• What are the main components of the urinary system?

  Kidneys, ureters, bladder, urethra
• What is the primary function of the kidneys?

  Filter the blood and produce urine
• How many nephrons are approximately in each kidney?

  About 1 million nephrons
• What is the consequence of a low nephron count?

  Possibly associated with CKD and hypertension
• What is the functional unit of the kidney?

  The nephron
• What does the nephron do?

  Filters blood, reabsorbs nutrients, excretes waste
• What is the role of the collecting ducts?

  Drain urine from nephrons into renal pelvis
• What is the glomerulus?

  A bundle of capillaries in the nephron
• What percentage of plasma enters the nephron?

  20% of the plasma
• How much plasma is filtered daily?

  180 L/day
• What are the three layers plasma passes through to enter the tubule?

  Capillary wall, basement membrane, podocytes
• What is the function of podocytes in Bowman’s capsule?

  Form filtration slits for glomerular filtration
• What is the primary function of the proximal convoluted tubule?

  Site of tubular reabsorption of nutrients
• What percentage of filtered fluid is reabsorbed in the proximal convoluted tubule?

  124 mL/min reabsorbed
• What is transepithelial transport?

  Movement of substances across epithelial cells
• What type of transport is used for sodium reabsorption?

  Both passive and active transport
• What is the role of the loop of Henle?

  Set up a vertical osmotic gradient
• What are the two types of nephrons?

  Cortical and juxtamedullary nephrons
• What is the osmolarity in the cortex and medulla?

  300 mOsm/L in cortex, 1200 mOsm/L in medulla
• What is the countercurrent multiplication system?

  Process using energy to set up a concentration gradient
• How does the vasa recta contribute to the osmotic gradient?

  Blood becomes saltier as it descends
• What happens to urine in the loop of Henle?

  Urine leaves more dilute than when it entered
• What regulates the remaining 20% of water reabsorption?

  Hormonal control via vasopressin (ADH)
• What is the role of vasopressin (ADH)?

  Increases permeability of distal and collecting tubules
• How do osmoreceptors in the hypothalamus respond to dehydration?

  They detect increased osmolarity and release ADH
• What happens when ADH acts on V2 receptors?

  AQP-2 channels are inserted into the membrane
• What is the effect of ADH on urine concentration?

  ADH causes concentrated urine and decreased osmolarity
• What is the relationship between ADH and osmotic gradient?

  ADH release is influenced by osmotic gradient
• What is the summary of nephron function?

  Filters blood, reabsorbs nutrients, excretes waste
• What is the Glomerular Filtration Rate (GFR)?

  Rate at which blood is filtered in kidneys
• What is the role of loop diuretics?

  Inhibit sodium reabsorption in the loop of Henle
• What is the Renin-Angiotensin-Aldosterone System (RAAS)?

  Hormonal system regulating blood pressure and fluid balance
• What is the primary function of the nephron?

  Filtration and reabsorption of blood
• What is the first segment of the nephron?

  Proximal Convoluted Tubule
• What type of transport is primarily used for sodium reabsorption in the proximal tubule?

  Active transport
• How is water reabsorbed in the proximal tubule?

  Passive transport of H₂O
• What are the main processes occurring in the proximal tubule?

  • Reabsorption
  • Secretion
  • Active and passive transport
• What percentage of filtered Na⁺ is actively reabsorbed in the proximal tubule?

  67%
• What follows sodium reabsorption in the proximal tubule?

  Chloride follows passively
• What determines the secretion of H⁺ in the proximal tubule?

  Acid-base status of the body