Omega 3 fatty acids are important because they

They help reduce risk factors for heart disease, including high cholesterol and high blood pressure.

If it's a smaller child or infant, place one on the middle of the chest and on the child's back. (if it is a bigger child with enough room for two, place one on the upper right/your left of the chest, and one on the lower left/your right) the pads should never touch each other. 

The lungs are the bags that hold air as it is inhaled oxygen gas that is in the air moved into the blood-and the heart pumps to move this oxygenated blood to cells in the body that need energy