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An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or just pacemaker is an implanted medical device that generates electrical impulses delivered by electrodes to the chambers of the heart either the upper atria, or lower ventricles to cause the targeted chambers to contract and ...
The pacemaker potential is thought to be due to a group of channels, referred to as HCN channels (Hyperpolarization-activated cyclic nucleotide-gated). These channels open at very negative voltages (i.e. immediately after phase 3 of the previous action potential; see below) and allow the passage of both K + and Na + into the cell.
Biofluorescence describes the absorption of ultraviolet or visible light and the sub sequential emission of photons at a lower energy level (S_1 excited state relaxes to S_0 ground state) by intrinsically fluorescent proteins or by synthetic fluorescent molecules covalently attached to a biomarker of interest.
The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approximately 15 mm long, 3 mm wide, and 1 mm thick, located directly below and to the side of the superior vena ...
A mysterious light has been blinking in space every 21 minutes for 35 years–and scientists have no idea what it is. What could it be?
"The pacemaker rate was variable from about 80 to 120 pulses per minute, and likewise the voltage variable from 1.5 to 120 volts". [59] In 1928, the apparatus was used to revive a stillborn infant at Crown Street Women's Hospital in Sydney, whose heart continued "to beat on its own accord", "at the end of 10 minutes" of stimulation.
An ectopic pacemaker, also known as ectopic focus or ectopic foci, is an excitable group of cells that causes a premature heart beat outside the normally functioning SA node of the heart. It is thus a cardiac pacemaker that is ectopic , producing an ectopic beat .
The cardiac pacemaker is the heart's natural rhythm generator. It employs pacemaker cells that generate electrical impulses, known as cardiac action potentials . These potentials cause the cardiac muscle to contract, and the rate of which these muscles contract determines the heart rate .