heat definition In physics, a form of energy associated with the movement of atoms and molecules in any material. The higher the temperature of a material, the faster the atoms are moving, and hence the greater the amount of energy present as heat.
Cilia (singular: cilium) are microscopic, hair-like structures that extend outwardfrom the surface of manyanimal cells. These structures are important in the cell cycle and replication, and cilia play a vital part in human and animal development and in everyday life. A typical cilium is between one and ten micrometers long, and usually less than one micrometer wide.
Cilia are composed of smaller protein pieces called tubulin and are connected to the cell by the basal body. These tubulin pieces are manufactured in the cell and then transported to the surface. When motile cilia work together to move molecules and liquids past the cells, it is called intraflagellar transport.