the skin

By

Temitope Olubode

06/13/2010

Major regions of the skin Consists of three major regions

Epidermis (superficial region)

Dermis (middle region)

Hypodermis (superficial fascia)

Epidermis Keratinized stratified squamous epithelium

Cells of epidermis

Keratinocytes—produce fibrous protein keratin

Melanocytes Produce pigment melanin

Epidermal dendritic (Langerhans) cells—macrophages that help activate immune system

Tactile (Merkel) cells—touch receptors

Dermis

Strong, flexible connective tissue

Cells include fibroblasts, macrophages, and occasionally mast cells and white blood cells

Consist of two layers:

Papillary

Reticular

Hypodermis

Hypodermis –The third and deepest layer of the skin also called the subcutaneous layer. Composed of lipocytes (fat cells). Protects the deeper tissues of the body and acts as insulation for heat and cold.

Mostly adipose tissue

Skin Color Three pigments contribute to skin color:

Melanin Yellow to reddish-brown to black, responsible for dark skin colors

Produced in melanocytes; migrates to keratinocytes where it forms “pigment shields” for nuclei

Freckles and pigmented moles

Local accumulations of melanin

2. Carotene Yellow to orange, most obvious in the palms and soles

3.Hemoglobin Responsible for the pinkish hue of skin

Skin Accessory Organs

Sweat glands consists of apocrine gland sweat duct and sweat pore

Oil glands Widely distributed, sebum that softens hair and skin

Most develop from hair follicles

Hairs consist of arrector pili, hair follicles, hair rot and hair shaft

Nails consists of nail bed, nail body, nail root, cuticle, lunula