transport (trans´port)

The movement or transference of biochemical substances in biologic systems. [L. transporto, to carry over, fr. trans- + porto, to carry]
active t. the passage of ions or molecules across a cell membrane, not by passive diffusion but by an energy-consuming process at the expense of catabolic processes proceeding within the cell; in active t., movement takes place against an electrochemical gradient.
axoplasmic t. transport by way of flow of axoplasm toward cell soma (retrograde) or toward axon terminal (anterograde).
facilitated t. the protein-mediated t. of a compound across a biomembrane that is not ion-driven; a saturable t. system.passive t;
hydrogen t. the transfer of hydrogen from one metabolite (hydrogen donor) to another (hydrogen acceptor) through the action of an enzyme system; the donor is thus oxidized and the acceptor reduced.
paracellular t. solvent movement across an epithelial cell layer through the tight junctions between cells. Cf. transcellular t.
passive t. facilitated t
transcellular t. solute movement across an epithelial cell layer through the cells. Cf. paracellular t.
vesicular t. transcytosis


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