Sodium

"I am indebted to the directors of the Castner-Kellner Company... or affording me the opportunity, in connection with this lecture, of actually witnessing the modern process of manufacturing sodium as it is carried out at ... And in concluding may I be permitted to recall here the feelings to which that visit to Wallsend gave rise. ...Before me, stretching down to the river, was the factory where a score of workers, clad in helmets and gauntlets and swathed like so many , travel-stained and war-worn, their visages lit up by the yellow soda flames, and their ears half-deafened with the sound of exploding hydrogen—a veritable inferno—were repeating on a Gargantuan scale the little experiment first made a century ago in the cellars of this building; turning out, day and night, hundredweights of the plastic metal in place of the little pin-heads which then burst upon the astonished and delighted gaze of Davy."

"Behind me was the magnificent power-house... furnishing not only the electrical energy which transformed the soda into sodium, but diffusing this energy for a multitude of other purposes over an entire district—a noble temple to the genius and prescience of Faraday. Surely one might here say, if you desire to see the monuments of these men, look around!"

"The composition of every cell is different from that of the material in which it exists. ...The striking feature of a neuron at rest ...its contents are one-tenth as rich in sodium s as the external fluid and... ten times richer in ions. ...[S]odium ions will leak into the cell and potassium will leak from it. ...[T]he membrane possesses pumps to offset the flow ...sodium-potassium adenosine triphosphotase pumps ...can steadily exchange three sodium ions for two potassium ...Every neuron contains about a million pumps... and every pump can swap about 200 sodium ions for 130 potassium ions every second.. ...The pumps ...maintain that sodium potassium imbalance, and... the inside of each neuron at seventy millivolts negative to the outside. ...[T]hat helps to explain the near-permanent demand for oxygen ..."

"[A] change in the electrical state of the nerve cell... hurries along the axon in advance of the impulse... partnered by an alteration in the permeability of the membrane... permitting sodium ions to pour into the cell... [T]he more... ions rush in the more channels are opened to increase this torrent. Suddenly, with a change in the membrane potential from negative to positive... sodium channels close. Another group... opens, permitting potassium ions to flow out... until the... minus seventy millivolts is achieved again."

"The transmission of an impulse is not electrical... The so-called spike... the shift in membrane potential between -70 millivolts and +40 millivolts, is the electrical manifestation of each nerve impulse. ...[T]here is plainly more to it—with channels opening, pumps operating, and sodium scurrying back and forth—than... an electrical impulse along a copper wire."

"[C]onsiderable attention has been paid to the 'blood-brain barrier'. ...[I]n 1909 ...it was realized that certain substances, such as dyes, did not reach the brain. ...[T]hey arrived swiftly within every other tissue but not the brain or spinal cord. ...There was apparent restriction both to foreign substances (sucrose, insulin, penicillin) and natural ones (urea, sodium, potassium, creatinine). By comparison with muscular tissue, where there is equilibrium between blood and tissue for the injected substance within seconds or minutes, such a balance in the brain may take hours."