🧪 Salivary Composition and Secretion: From Isotonic to Hypotonic

Learn how saliva is formed and modified in acinar and ductal cells. Understand why initial isotonic plasma-like fluid becomes hypotonic saliva through Na⁺ and Cl⁻ reabsorption and K⁺ and HCO₃⁻ secretion. Perfect for physiology exams and medical students.