Title: Reabsorption and Secretion Along the Proximal Tubule - Anatomy & Physiology - WikiVet English
Headings: Reabsorption and Secretion Along the Proximal Tubule - Anatomy & Physiology
A Tribute to Nick Short
Reabsorption and Secretion Along the Proximal Tubule - Anatomy & Physiology
Contents
Introduction to Reabsorption
Proportion of Filtered Substances Reabsorbed in the Proximal Tubule
Epithelial Transport
Ions and Compounds
Sodium
Water
Potassium
Urea
Glucose
T Max and Splay
The Kidneys Role In Glucose Regulation
The Secretion of H+ and the Reabsorption of HCO3-
Reabsorption of HCO3-
Protein
Primary Active Secretion - Organic Acids and Bases
Calcium
Revision

Content: Water and chloride follow sodium passively and many other ions, compounds and molecules are absorbed through co-transporters with sodium. However it is vital that intracellular levels of sodium remain low to favour this reabsorption so it falls to the sodium/potassium ATPase and sodium pump to remove sodium from the cell. Also to a lesser extent active transport of protons (H + ). As well as directly sodium linked transport secondary active transport also plays a part however this does tend to be powered by sodium movement. Passive transport also has a role
Transport capacity is well above what is needed for normal plasma concentrations to ensure that adequate absorption occurs and that there is little/no wastage. As sodium, chloride and water are reabsorbed at the same rate, the filtrate concentrations remains the same along the proximal tubule. Only the volume of the filtrate decreases. Ions and Compounds
A summary of the reabsorption along the proximal tubule
A sodium pottasium ATPase. ( Courtesy of Phi-Gastrein)
The following ions and compounds are reabsorbed or secreted partly or completely in the proximal tubule: Sodium
The majority (70%) of sodium is reabsorbed in the proximal tubule.