Question

Unidirectional transport of a material from the lumen (cavity) of an organ into one side of a cell and out the other side of the cell into the ecf is called __________. unidirectional transport of a material from the lumen (cavity) of an organ into one side of a cell and out the other side of the cell into the ecf is called __________. transcellular transport secretion paracellular transport absorption

Answer 1

The right answer is: transcellular transport.

Water and solutes can be transported:
- through an epithelium by successively crossing the apical and basolateral membranes: transcellular transport (for example in intestinal absorption of renal filtration or reabsorption)
- between the cells through the tight junctions: paracellular transport.

In transcellular transport, one step is active and the other is passive. For example, in the case of sodium reabsorption, the active step is the basolateral sodium exit by the Na + / K + -ATPase, which consumes energy and makes it possible to maintain an electrochemical gradient favourable to the passive input of sodium across the apical membrane in the direction of the electrochemical gradient.