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: 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. It is reabsorbed into the cytosol of the epithelial cells either alone by diffusion through ion channels followed by water and chloride or together with another product such as glucose or AA using a co-transporter by secondary active co-transport. To maintain the concentration gradients and allow the diffusion to continue it is essential that sodium is not allowed to build up within the cell. This is the job of the sodium/potassium ATPase Pump and is an example of primary active transport. This pump removes three sodium ions from the cell and pumps two potassium ions back in. This creates a high concentration of potassium within the cell but this is corrected by potassium ion channels in the basolateral membrane which allow potassium to diffuse back into the interstitium.