释义 |
DictionarySeeprotonEncyclopediaSeepumpproton pump
pump [pump] 1. an apparatus for drawing or forcing liquid or gas.2. to draw or force liquids or gases.blood pump a machine used to propel blood through the tubing of extracorporeal circulation devices.breast pump a pump for taking milk from the breast.calcium pump the mechanism of active transport of calcium (Ca2+) across a membrane, as of the sarcoplasmic reticulum of muscle cells, against a concentration gradient; the mechanism is driven by hydrolysis of ATP.enteral feeding pump an infusion pump specifically designed for administration of a solution through a tube" >feeding tube.insulin pump see insulin pump.intra-aortic balloon pump see intra-aortic balloon pump.muscle pump compression of veins by the contraction of skeletal muscles, forcing blood towards the heart against the flow of gravity; seen particularly in the deep veins of the lower limbs. Called also venous pump.Na+-K+ pump sodium-potassium pump.proton pump a system for transporting protons across cell membranes, often exchanging them for other positively charged ions.sodium pump (sodium-potassium pump) the mechanism of active transport driven by the energy generated by Na+,K+-ATPase, by which sodium (Na+) is extruded from a cell and potassium (K+) is brought in, so as to maintain the low concentration of sodium and the high concentration of potassium within the cell with respect to the surrounding medium. A high concentration of intracellular potassium is necessary for vital processes such as protein biosynthesis, certain enzyme activities, and maintenance of the membrane potential of excitable cells. Called also Na+-K+ pump.stomach pump see stomach pump.venous pump muscle pump.pro·ton pumpmolecular mechanism for the net transport of protons across a membrane; usually involves the activity of an ATPase.proton pump An ATP-dependent H+ ion transporter present in the membranes of lysosomes and vacuoles, which maintains a low pH (4.5-5.0) inside these organelles. Proton pumping is also required in the electron transport chain, where an NADH (or FADH) is oxidised to NAD+ (or FAH+), releasing 2 electrons and a proton.pro·ton pump (prō'ton pŭmp) Molecular mechanism for the net transport of protons across a membrane; usually involves the activity of adenosine triphosphatase. proton pump a specialized assembly of proteins in a cell membrane which transports protons against a concentration gradient. |