An important similarity between a sub-lethal dose and a lethal dose is, they both produce adverse affect to which the dose is applied. However, they differ on the level of toxin or noxious substance causing adverse reaction. So, lethal dose causes an organism to die while in the sub-lethal, the dose is not quite enough to cause death.
The function of the atria is to collect and pump blood into the ventricles. The function of the ventricles is to pump blood into systemic and pulmonary circulations.
