Hair and Nails - bulb Much like in the epidermis as new...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Hair and Nails While the stratum corneum of the skin is composed of a relatively pliable form of keratin, hair and nails are composed of a hardened form of keratin. Hair is found almost everywhere on the body, but a quick examination of your body shows that all hair is not equal. The fine, unpigmented hair covering fetuses is called lanugo, while the fine, unpigmented hair of children and women is vellus hair. The coarse, long, pigmented hair of the scalp, pubic and axillary regions is terminal hair. Hair itself is a filament of keratinized cells (recall that keratinized cells are flattened, denucleated , dead cells). The shaft of the hair is what is visible above the surface of the skin while the root lies within the hair follicle . The hair bulb is a swelling within the follicle that is encased in a dermal papilla . The dermal papilla provides nutrients to the keratinocytes found within the hair
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: bulb. Much like in the epidermis, as new cells are formed in the bulb, older cells are pushed towards the surface and emerge as hair. The hair follicle consists of both an epithelial root sheath which is an extension of the epidermis and a connective tissue root sheath which is derived from the dermis and surrounds the epithelial root sheath. Hair receptors entwine each follicle while piloerector muscles are smooth muscles that cause goose bumps. In addition to sensation, hair is an important communicative and protective tool. Growth of terminal facial, pubic and axillary hair indicates sexual maturity and helps distribute sexual scents. Eyebrows, eyelashes and vibrissae protect the eyes and nose. Finger and toe nails are also densely packed cells filled with hard keratin. These clear, hard derivatives of the stratum corneum protect humans' fleshy and sensitive fingertips....
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online