At the death of his father, the family moved to Hol-
land and settled in Utrecht, where he attended school.
In 1878 he entered the University of Utrecht as a medi-
cal student. In 1885, after receiving his medical doctor-
ate, he was appointed successor to A. Heynsius,
professor of physiology at the University of Leiden, and
stayed there until his death.
He conducted a great deal of research on the heart.
To measure the electric currents created by the heart,
he invented a string galvanometer (called the Einthoven
galvanometer) and was able to measure the changes of
electrical potential caused by contractions of the heart
muscle and to record them, creating the electrocardio-
gram (EKG), a word he coined, which is a graphic
record of the action of the heart. This work earned him
the Nobel Prize in physiology or medicine for 1924. He
published many scientific papers in journals of the
time. He died on September 29, 1927.
electrical conductivity Having the ability to con-
duct electricity.
electrical resonance An effect in which the resis-
tance to the flow of an electrical current becomes very
small over a narrow frequency range.
electrochemical gradient The relative concentration
of charged ions across a membrane. Ions move across
the membrane due to the concentration difference on
the two sides of the membrane plus the difference in
electrical charge across the membrane.
electrochemistry The branch of chemistry that is
involved in studying reactions of electrodes and chemi-
cal changes resulting from electrical current or the pro-
duction of electricity by chemical means.
electrocyclic reaction A MOLECULAR REARRANGE-
MENTthat involves the formation of a SIGMA(σ) BOND
between the termini of a fully conjugated linear pi-elec-
tron system (or a linear fragment of a pi-electron sys-
tem) and a decrease by one in the number of PI(π)
BONDs, or the reverse of that process. For example,
The stereochemistry of such a process is termed
“conrotatory” or ANTARAFACIALif the substituents at
the interacting termini of the conjugated system both
rotate in the same sense, for example,or “disrotatory” or SUPRAFACIALif one terminus
rotates in a clockwise and the other in a counterclock-
wise sense, for example,See alsoCONJUGATED SYSTEM; PERICYCLIC REAC-
TION.electrode A conductive material that, in an electric
field, gives off, captures, or controls electrons (anode)
or ions (cathode), such as in a battery. It is a surfaceelectrode 89