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
Modern animals are classified into between 30 and 35 phyla: all major modern phyla were present at the beginning of the Cambrian, along with a great variety of now-extinct phyla recorded in the Burgess Shale (Cambrian) in Canada.