1. Introduction
  1.1 Background
  1.2 Objectives
2. Anatomy of the Urinary System
  2.1 Kidneys
      2.1.1 Structure and Function
      2.1.2 Nephron Anatomy
  2.2 Ureters
      2.2.1 Structure and Function
  2.3 Urinary Bladder
      2.3.1 Structure and Function
  2.4 Urethra
      2.4.1 Structure and Function
3. Comparative Analysis of Urinary Systems
  3.1 Mammals
      3.1.1 Humans
      3.1.2 Canines
      3.1.3 Felines
  3.2 Birds
      3.2.1 Avian Urinary System Adaptations
  3.3 Reptiles
      3.3.1 Reptilian Urinary System Variations
  3.4 Fish
      3.4.1 Aquatic Adaptations in Fish Urinary Systems
4. Function of the Urinary System
  4.1 Filtration and Reabsorption
  4.2 Regulation of Fluid and Electrolyte Balance
  4.3 Waste Elimination
  4.4 Hormonal Regulation
5. Evolutionary Significance of Urinary System Variations
  5.1 Adaptations to Different Environments
  5.2 Influence of Diet and Water Availability
  5.3 Phylogenetic Relationships and Urinary System Evolution