Epidermis

the layer that responds to pressure or injury to the skin

upper layer (top layer on top of dermis)

stratified keratinized squamous epithelium

• Keratinocytes
• Melanocytes
• Merkel cells
• Langerhans cells

produces keratin. They arise at the lower part of epidermis & are pushed up as new ones are created. As they reach the top they flatten out. At this time they are filled with keratin and have died. We get a new epidermis every month

make melanin (dark pigment) which is transferred to the keratinocytes. The melanin protects DNA from UV ray damage. Melanin production is increased as a result of UV exposure. Skin tone is a result of the rate at which melanin is destroyed by lysosymes.

Melanin protects DNA from UV Ray Damage

associated with a sensory nerve ending - it is a touch receptor

star shaped cells that form part of the immune system & use receptor mediated endocytosis to engulf foreign substances.

strata

the thickness of skin

Epidermis is the section of skin that protects and waterproofs the body

a basal layer that gives rise to newly formed keratinocytes & melanocytes.

statum basal is attached to underlying dermis & is a single row of stem cells with a high rate of mitosis. The high mitotic rate pushes the cells into the next layer.

pushes the cells into the next layer

a spiny layer of mature keratinocytes that have formed tonofilaments (prekeratin intermediate filaments)

several layers thick and also has langerhans cells.

a granulayer where keratinocytes flatten & plasma membrane thickens

4-5 layers of flat keranocytes with the cells changing becoming waterproof and keratinized.

a clear layer with cells that die from getting no nutrients

Stratum Lucidum is found in thick skin and appears as a clear band under the microscope.

horny layer that protects against abrasions & entry of foreign substances. The cells are dead flat keratinocytes filled with keratin.

Stratum Corneum is many layers found in thick or thin skin. It is the outermost layer (the surface of your body)

at this point the cells are dead, have no organelles, & are filled with keratin & hold waterproofing glycolipids in between cells.