Lecture Notes: Overview of Kidney Function

Introduction to Kidneys

• The kidneys hold about 22% of the body's blood supply.
• Approximately 1.1 liters of blood flow through the kidneys per minute.
• In a person with about 5 liters of blood, all blood passes through the kidneys in about 5 minutes.

Functions of the Kidneys

• The primary purpose of the kidneys is to filter blood and produce urine.
• Blood Flow Process:
  • Blood enters through the renal artery.
  • Blood exits through the ureters after processing.
  • The kidneys regulate waste products, acidity, and osmolarity of blood, which are vital for homeostasis.

Key Functions of Kidneys

1. Filtration:
   • Blood is filtered to remove waste products and retain important molecules (ions, amino acids, glucose).
2. Collection:
   • Processed filtrate is collected to form urine.

Nephron: The Functional Unit

• The nephron is the smallest functional unit of the kidney and is responsible for filtration and collection.
• Structure of the nephron:
  • Located between the renal cortex (outer shell) and renal medulla (inner area).
  • The nephron processes blood, reabsorbing necessary substances and allowing waste to form urine.

Key Structures in the Kidney

• Renal Cortex: Outer part of the kidney.
• Renal Medulla: Inner part of the kidney.
• Renal Calyx: The initial collection point of urine.
• Renal Pelvis: Central area where calyces converge to collect urine before it exits the kidney.
• Ureter: Tube that carries urine from the kidney to the bladder.
• Hilum: Area where the renal artery, renal vein, and ureter exit the kidney.

Importance of Kidney Function

• Kidneys play a crucial role in maintaining homeostasis:
  • Regulate blood pH: Control hydrogen ion levels.
  • Regulate blood pressure: Excrete sodium and chloride ions to manage blood pressure levels.
  • Regulate osmolarity of blood.
  • Excrete waste products, primarily urea.

Conclusion

• The kidneys are vital organs for filtering blood and producing urine, essential for maintaining homeostasis in the body.