Hair is made of a tough protein called keratin. A hair follicle anchors each hair into the skin. The hair bulb forms the base of the hair follicle. In the hair bulb, living cells divide and grow to build the hair shaft. Blood vessels nourish the cells in the hair bulb, and deliver hormones that modify hair growth and structure at different times of life.
Phylum definition, Biology. the primary subdivision of a taxonomic kingdom, grouping together all classes of organisms that have the same body plan. See more. Dictionary.com
In biology, a phylum (/ËfaÉªlÉm/ ; plural: phyla) is a taxonomic rank below kingdom and above class. Traditionally, in botany the term division was used instead of phylum, although from 1993 the International Code of Nomenclature for algae, fungi, and plants accepted the designation phylum.