chap 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 + 1/2pv 2 + pgh = constant , through the fluid
• Bernoulli’s principle Bernoulli’s equation applied at constant depth: P1 + 1/2pv1 2 = P2 + 1/2pv2 2
• 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
• Poiseuille’s law for resistance the resistance to laminar flow of an incompressible fluid in a tube: R = 8ηl/πr 4
• 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)πr 4 /8ηl
• 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