Images Dated 15th December 2003
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Choose from 19 pictures in our Images Dated 15th December 2003 collection for your Wall Art or Photo Gift. Popular choices include Framed Photos, Canvas Prints, Posters and Jigsaw Puzzles. All professionally made for quick delivery.
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Featured 15 Dec 2003 Print
Illustration of electrical conduction in the heart
Electrical conduction in heart. Illustration of a human heart, showing the specialised tissue that conducts the electrical signals governing heart- beats. The heartbeat starts in the heart's natural pacemaker, the sinoatrial (SA) node (green). This small area of specialised muscle cells emits an electrical impulse about 70 times a minute. The impulse spreads through the muscles of the atria (upper heart chambers), making them contract, and is carried via special fibres to the atrioventric- ular (AV) node (orange). The AV node delays the impulse to allow the ventricles (lower heart cham- bers) to fill, before effecting ventricular con- traction via branches of the bundle of HIS (red)
© JOHN BAVOSI/SCIENCE PHOTO LIBRARY
