Kidney Anatomy and Physiology

Jun 30, 2024

Kidney Anatomy and Physiology

Introduction

  • Don't buy detox products; liver and kidneys naturally detoxify.
  • Focus on kidney anatomy and blood cleaning physiology.

Kidney Functions

  • Regulate fluid levels.
  • Ion balance.
  • Clear blood waste, excrete through urine.

Kidney Location and Structure

  • Size: about human fist.
  • Location: Sides of the spinal column, above the lower back.
  • Positioned behind the abdominal cavity.

Adrenal Glands

  • Positioned atop kidneys.
  • Produce adrenaline.

Ureters and Urethra

  • Ureters: transport urine to the bladder.
  • Urethra: transports urine out of the body.
  • Shorter urethra in people with vaginas → higher risk of UTIs.

Kidney Cross-Section

  • Cortex: outermost layer of kidney tissue.
  • Medulla: middle layer.
  • Renal Pelvis: uppermost end of the ureter, carries pee.

Hilum

  • Where renal artery, vein, and pelvis converge.

Functional Anatomy

Nephrons

  • Functional units of the kidney (1 million per kidney).

Medulla

  • Blood vessels in renal columns transport blood to/from cortex.

Renal Pyramids

  • Funnel waste to renal pelvis.
  • Have collecting ducts merging into the renal pelvis.

Blood Filtration Process

Blood Inflow

  • Renal arteries: 20% of cardiac output.
  • Arterioles branch into glomerulus (tiny capillaries).
  • Capillaries have tiny holes (fenestrated capillaries).

Glomerulus

  • Filters small particles (glucose, amino acids, water).
  • Retains big particles (blood cells, large proteins).

Bowman’s Capsule

  • Wraps around glomerulus, sends waste into tubules.

Renal Corpuscle

  • Combination of glomerulus and Bowman’s capsule.

Tubule Pathways

  • Proximal convoluted tubule → Loop of Henle → Distal convoluted tubule → Collecting duct.
  • Peritubular capillaries (around tubules).
  • Vasa recta (around Loop of Henle).

Kidney Filtration Steps

Glomerular Filtration

  • Filters 125 mL/min of blood.
  • Outputs ions, water, glucose, lipids, amino acids, urea.

Tubular Reabsorption

  • Happens in convoluted tubules and Loop of Henle.
  • Key reabsorbed items: water, sodium, glucose, amino acids, ~50% urea.

Loop of Henle

  • Descending limb: water exits.
  • Ascending limb: ions exit.
  • Osmolality-driven water and ion flow.

Distal Convoluted Tubule

  • Uses energy to pump ions out.

Collecting Tubule

  • Similar mechanisms to Distal Convoluted Tubule.

Tubular Secretion

  • Transports unwanted large molecules from blood into tubules.
  • Regulates blood pH (7.4) by moving hydrogen ions out.

Urine Formation

  • Urea cycle: some reabsorbed, then re-secreted.
  • Final urine into renal pyramids → renal pelvis → ureters → bladder → outside body.
  • Produces ~180 liters of filtrate/day, ~1.5 liters of urine.

Conclusion

  • Introductory video; more detailed content to follow.
  • Viewer engagement invited for future topics.