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
Phylum. In biology, a phylum is a taxonomic rank below kingdom and above class. Traditionally, in botany the term division is used instead of phylum, although in 1993 the International Botanical Congress accepted the designation phylum.iktionary (0.00 / 0 votes) Rate this definition: phylum (Noun). A rank in the classification of organisms, below kingdom and above class; also called a division, especially in describing plants; a taxon at that rank. Mammals belong to the phylum Chordata. Origin: From phylum, from Ïá¿¦Î»Î¿Î½.