Proximal Tubule
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Renal
- Renin
- Angiotensin II
- Aldosterone
- ADH
- RAAS System
- Kidney Overview
- Nephron Structure
- Glomerulus
- Proximal Tubule
- Loop of Henle
- Distal Tubule
- Collecting Duct
- Proximal (Convoluted) Tubule
- First segment the filtrate traverses after glomerular filtration
- Two major roles
- Reabsorption of solutes
- Majority of solute reabsorption occurs in early proximal tubule
- Na+
- Major ion undergoing reabsorption by Na+/K+ ATPase and Na/H antiporters
- Always coupled to chloride and water reabsorption
- Water
- Water is reabsorbed paracellularly by passive diffusion through tight junctions or by facilitated diffusion via aquaporins
- Important nutrients
- Includes amino acids, vitamins, salts, glucose, bicarbonate, water
- Secretion of waste
- Commonly secreted solutes include H+, urea, ammonia, K+
- Reabsorption of solutes
- Overall effect:
- Amount of filtrate in nephron is reduced
- Solute composition in nephron is altered
- But overall concentration of solutes does not change