Lecture on Excretion, Homeostasis, and Kidney Anatomy

Introduction

• Discussion on excretion and homeostasis.
• Nitrogenous wastes: Ammonia and Urea.
  • Ammonia converted to Urea by the liver.
  • Urea still circulates in the blood.
• Kidneys: Excrete urea and help maintain homeostasis.

Kidney Function

• Excretion:
  • Bean-shaped organ receives blood high in urea, salts, and water.
  • Blood enters via the renal artery, leaves via the renal vein with less urea, salt, and water.
  • Produces urine to remove excess waste.
• Homeostasis:
  • Maintains optimal internal conditions.
  • Regulates water levels by adjusting urine production.
  • Increases urine production with excess water intake; retains water when needed.

Additional Kidney Functions

• Not covered in detail.

Urinary System Structure

• Typical components: two kidneys, ureters, and a bladder.
• Blood supply:
  • Renal artery: Blood enters the kidney.
  • Renal vein: Blood exits the kidney.

Kidney Anatomy

• Sections of the kidney:
  • Capsule: Outermost layer.
  • Cortex: Middle layer, important for internal structures.
  • Medulla: Inner region, also important.
  • Pelvis: Central area.
• Nephron:
  • Functional unit of the kidney.
  • Structure includes Bowman's capsule, proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), and collecting duct.
  • Produces urine via these components.

Nephron Details

• Nephrons are microscopic; about 1 million per kidney.
• Structure:
  • Bowman's Capsule: Start of the nephron.
  • Proximal Convoluted Tubule (PCT): Near Bowman's capsule; complex, twisted tubes.
  • Loop of Henle: U-shaped structure.
  • Distal Convoluted Tubule (DCT): Further from Bowman's capsule.
  • Collecting Duct: Final segment.
• Location within Kidney:
  • Cortex: Bowman's capsule, PCT, DCT, and part of the collecting duct.
  • Medulla: Loop of Henle.
  • Pelvis: Collecting duct extends here.

Examination Tips

• Be prepared to label parts of the nephron and kidney.
• Understand the terms and where structures are located within the kidney.

Conclusion

• Introduction to kidney anatomy and its role in excretion and homeostasis.