Anaesthesia Fundamentals | Physiology | Tubular Transport and the Proximal Tubule

Tubular Transport and the Proximal Tubule
Session Overview
Description
This session describes the mechanisms behind alteration of tubular fluid composition after filtration has taken place, as well as the detailed functions of the proximal tubule.

Learning Objectives
By the end of this session you will be able to:

• List the mechanisms by which glomerular filtrate is modified
• Explain electrolyte absorption by the proximal tubule
• Describe proximal tubular handling of other solutes
• State the role of the peritubular capillaries

Prerequisites
Before commencing this session you should complete:

• Renal Morphology, Blood Supply and Glomerular Filtration (001-0654)

Urine has a considerably different electrolyte and metabolite composition and a lower volume, when compared to glomerular filtrate, which is essentially cell and protein free plasma. Transport of solutes and water across the renal tubular epithelium can occur between cells, i.e. paracellular movement, or through cells, i.e. transcellular movement.

Secretion describes movement of substance(s) such as electrolytes and drugs from the blood to the tubular fluid.

Reabsorption is the movement of substance(s) from the tubular fluid into the blood.

There are different forces involved in facilitating these processes. This session explains how the processes of secretion and absorption apply in altering the composition of the filtrate.