When you are sick, your lymph nodes will swell with extra

Matter is made up of tiny particles called atoms

Explanation:

All the things, whether living or non-living, are made up of matter. Matter is composed of tiny particles known as atom. Atoms were discovered in 19th century. Atoms are composed of subatomic particles- electrons, protons and neutrons. An atom cannot be observed using a standard microscope as it is very tiny. It can be viewed under an electron microscope.