Canadian Medical Guide > Biological Sciences > Biochemical Phenomena, Metabolism, and Nutrition > Metabolism > Biological Transport Terms and Definitions

Biological Transport

	Biological Transport, Active - The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.
	Capillary Permeability - The property of blood capillary vessels ENDOTHELIUM that allows for the selective exchange of substances between the blood and surrounding tissues and through membranous barriers such as the BLOOD-AIR BARRIER; BLOOD-AQUEOUS BARRIER; BLOOD-BRAIN BARRIER; BLOOD-RETINAL BARRIER; and BLOOD-TESTIS BARRIER. Small lipid-soluble molecules such as carbon dioxide and oxygen move freely by diffusion. Water and water-soluble molecules cannot pass through the endothelial walls and are dependent on microscopic pores. These pores show narrow areas (TIGHT JUNCTIONS) which may limit large molecule movement.
	Protein Transport - The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.
	Respiratory Transport - The processes of diffusion across the BLOOD-AIR BARRIER, and the chemical reactions coupled with diffusion that effect the rate of PULMONARY GAS EXCHANGE, generally at the alveolar level.
	RNA Transport - The process of moving specific RNA molecules from one cellular compartment or region to another by various sorting and transport mechanisms.

Biological Transport Medical Definitions and Terms