Kidney Function and Structure Lecture

Overview

• Focus on the kidney's functional unit, the nephron, and urine production.

Renal Corpuscle

• Components:
  • Glomerulus: A network of capillaries.
  • Bowman's Capsule/Renal Capsule: Simple squamous epithelium surrounding the glomerulus.
• Capsular Space: Where filtrate from the glomerulus collects.

Filtration Process

• Afferent Arteriole: Brings blood to the glomerulus.
• Efferent Arteriole: Blood exits through this smaller vessel.
• Filtrate:
  • Contains both nutrients and waste.
  • Formed as blood passes through fenestrated capillary of the glomerulus.
  • Protein-free to avoid losing large plasma proteins.

Proximal Convoluted Tubule (PCT)

• Function: Reabsorption of water, ions, and organic nutrients.
• Structure: Contains microvilli to increase reabsorption.

Loop of Henle

• Structure:
  • Descending Limb: Water reabsorption (thin segment).
  • Ascending Limb: Solute reabsorption (thick segment).

Distal Convoluted Tubule (DCT)

• Function:
  • Active transport of solutes.
  • Secretion of substances into the tubular fluid.
  • Under hormonal control for reabsorption.

Collecting Duct

• Function:
  • Reabsorbs water and some ions.
  • Concentrates urine as it moves to the renal pelvis.

Nephron Types

• Cortical Nephrons:
  • Shorter loops, primarily in the cortex.
  • 85% of nephrons.
• Juxtamedullary Nephrons:
  • Longer loops extending deep into the medulla.
  • 15% of nephrons.
  • Helps maintain medullary concentration gradient.

Blood Supply

• Peritubular Capillaries: Surround the tubular parts of the nephron.
• Vasa Recta: Associated with juxtamedullary nephrons.

Filtration Mechanism

• Driven by blood pressure.
• Passive process to remove small solutes and water.
• Leaves larger proteins and cells in the bloodstream.

Reabsorption and Secretion

• Reabsorption: Occurs mainly in PCT.
• Secretion: Important for removing large waste materials.

Urine Formation

• Begins at the renal corpuscle with filtration.
• Proceeds through the nephron with reabsorption and secretion.
• Concludes at the collecting ducts and renal pelvis.