Skin is the body's largest organ (yes, it's an organ!). If the skin of a 150-pound
person were spread out flat, it would cover approximately 20 square feet.
The skin is made up of two main layers, the dermis, an inner, living layer, and the
epidermis, an outer layer of dead cells.
The epidermis is several cells thick and is composed of a stratified squamus
epithelium of keratinized cells. What does THAT mean? An epithelium is a
layer of cells that serves as a protective covering over some surface. Squamus
means that they are flattened. Stratified means that it is layered. Keratin is
a fibrous protein that makes the cells stiff and horny. Your hair and fingernails
are made up of keratin. This is what makes the epidermis act as a
protective layer (BROWN). The GREEN part is known as the prickle layer.
These epidermal cells are constantly being shed (and provide food
for dust mites!) and are replaced from below by a basal layer of
columnar (column-shaped) cells (BLUE with PURPLE) The epidermal
layer of your skin is totally replaced every 52 to 75 days.
The dermis is made up of collagen and elastic fibers, permeated by hair follicles,
nerves, blood vessels, nerves, fat globules, and sweat glands. (ORANGE). The
average square inch ( 6.5 sq. cm) of skin holds 650 sweat glands, 20 blood vessels
and 60,000 melanocytes (pigment cells).
The skin is also a huge sensory receptor for heat, cold, pain, touch, and tickle.
Are you ticklish?