Lecture Notes on Kidney Anatomy (Martini Chapter 26)

Introduction

• Fetal development of kidneys occurs in three stages:
  • Pronephros: Disappears quickly.
  • Fetal kidney: Intermediate stage.
  • Adult kidney: Final developed stage.
• Cloa ("sewer"): Initial structure that subdivides into different organs:
  • Bladder and rectum (males)
  • Bladder, vagina, and rectum (females)
  • Tubes attached together; vaginal delivery can affect urethra leading to incontinence.

Ureteric Bud Development

• Ureteric bud: Outgrowth forming the ureter, connecting kidneys to bladder.
• Renal pelvis: Expanded area leading to minor and major calyces.
• Apoptosis separates calyces from collecting ducts, forming tubules.

Kidney Development

• Metanephros: Must meet with ureteric bud for adult kidney formation.
• Kidney ascent: Moves from pelvic cavity to around the 11th rib.
  • Reforms blood vessels and nerves during ascent.
• Multiple blood vessels in kidneys may occur and are typically benign.

Nephron Structure

• Nephron Components:
  • Proximal Convoluted Tubule (PCT): Close to glomerulus.
  • Nephron Loop (Loop of Henle): Loop structure in nephron.
  • Distal Convoluted Tubule: Farther from glomerular capsule.
• Bowman's Capsule: Forms around glomerular capillaries.
• Glomerulus and Capillaries: Afferent and efferent arterioles aid in filtration.

Blood Supply and Filtration

• Peritubular Capillaries: Assist in secretion and absorption.
• Arteries and Veins: Arise from renal arteries; vary in arrangement.
• Cortex and Medulla: Structural divisions with specific functions.

Renal Sinus, Fascia, and Fat

• Retroperitoneal location: Kidneys located around the 11th rib.
• Renal Fascia and Capsule: Provide protection and support.
  • Prevents kinking of ureters and blood vessels.
• Adipose Tissue (Perirenal Fat): Supports kidney position.

Kidney Structures

• Renal Cortex: Outer region with cortical tissue.
• Renal Medulla (Pyramids): Inner region with pyramid structures.
• Minor and Major Calyces: Collect and transport urine.

Histology and Microanatomy

• Glomeruli (Renal Corpuscles): Show distinct development stages.
• Tubules: Various types with differing functions and appearances.
• Micrographs: Show different sections and structures.

Summary of Renal Function and Filtration

• Cortical Nephrons: Primarily in the cortex.
• Juxtamedullary Nephrons: Extend into medulla, long loops.
• Filtration and Urine Formation: Process involving multiple structures.
  • Urine drips into minor calyces from papillary ducts.

These notes provide an overview of the renal anatomy and development process as discussed in Martini Chapter 26. They cover the key stages of kidney development, structural components, and functions related to the renal system.