p6 12

• Active transport


  The process in which a living membrane expends energy to move substances across
• Bernoulli's equation


  The equation resulting from applying conservation of energy to an incompressible frictionless fluid: P + 1/2pv2 + pgh = constant
• Bernoulli's principle


  Bernoulli's equation applied at constant depth: P1 + 1/2pv12 = P2 + 1/2pv22
• Dialysis


  The transport of any molecule other than water through a semipermeable membrane from a region of high concentration to one of low concentration
• Diffusion


  The movement of substances due to random thermal molecular motion
• Flow rate


  Abbreviated Q, it is the volume V that flows past a particular point during a time t, or Q = V/t
• Fluid dynamics


  The physics of fluids in motion
• Laminar


  A type of fluid flow in which layers do not mix
• Liter


  A unit of volume, equal to 10−3 m3
• Osmosis


  The transport of water through a semipermeable membrane from a region of high concentration to one of low concentration
• Osmotic pressure


  The back pressure which stops the osmotic process if one solution is pure water
• Poiseuille's law


  The rate of laminar flow of an incompressible fluid in a tube: Q = (P2 − P1)πr4/8ηl
• Poiseuille's law for resistance


  The resistance to laminar flow of an incompressible fluid in a tube: R = 8ηl/πr4
• Relative osmotic pressure


  The back pressure which stops the osmotic process if neither solution is pure water
• Reverse dialysis


  The process that occurs when back pressure is sufficient to reverse the normal direction of dialysis through membranes
• Reverse osmosis


  The process that occurs when back pressure is sufficient to reverse the normal direction of osmosis through membranes
• Reynolds number


  A dimensionless parameter that can reveal whether a particular flow is laminar or turbulent
• Semipermeable


  A type of membrane that allows only certain small molecules to pass through
• Terminal speed


  The speed at which the viscous drag of an object falling in a viscous fluid is equal to the other forces acting on the object (such as gravity), so that the acceleration of the object is zero
• Turbulence


  Fluid flow in which layers mix together via eddies and swirls
• Viscosity


  The friction in a fluid, defined in terms of the friction between layers
• Viscous drag


  A resistance force exerted on a moving object, with a nontrivial dependence on velocity