This article is about the natural pacemaker in the heart. For the medical device that simulates the function, see artificial cardiac pacemaker. Image showing the cardiac pacemaker or SA node, the normal pacemaker within the electrical conduction system of the heart. The contraction of cardiac muscle (heart muscle) in all animals is initiated by electrical impulses known as action potentials. The rate at which these impulses fire controls the rate of cardiac contraction, that is, the heart rate. The cells that create these rhythmic impulses, setting the pace for blood pumping, are called pacemaker cells, and they directly control the heart rate.
Woman of Wensleydale wearing a bedgown and petticoat, 1814. Modern petticoat. A petticoat or underskirt is an article of clothing; specifically an undergarment to be worn under a skirt or a dress. The petticoat is a separate garment hanging from the waist (unlike the chemise).
CLASSICOAT is a handy brushable rust remover. 1  Removes thin wet films of oil, grease etc.  Removes rust from steel components, especially machined surfaces of cast iron and forged components, reinforcement steel rods, slotted angles, ERW tubes etc. used in bus body construction etc.