Fast heart rate: Tachycardia means fast heart beat. Sinus node is the structure where normally heart rhythm and beat is originated, and it naturally responds to stimuli when the heart needs to beat faster. Inappropriate sinus tachycardia is when the heart is beating fast, when it shouldn't. ...Read more.
The atom is the smallest subdivision of an element which still retains the properties of that element. In fact, a very good definition of an atom is: the smallest part of an element that can enter into a chemical combination. There are around 118 elements known to man, of which 20-30 are really, really important.he parallel definition (to the element one above) for the molecule is: the smallest part of a compound that can enter into a chemical combination. Another definition, equally good, is that a molecule is the smallest stable part of a compound. Water is a typical example of a compound.
The thermoplastics all have repeat units, the smallest section of the chain that is identical. We call these repeat units unit cells. The vast majority of plastics, about 92%, are thermoplastics1. The groups of atoms that are used to make unit cells are called monomers. For some plastics, such as polyethylene, the repeat unit can be just one carbon atom and two hydrogen atoms. For other plastics, such as nylons, the repeat unit can involve 38 or more atoms.