Skin — The Largest Organ

The skin is…

The skin (integument) is the largest organ, uses all four tissue types, and has accessory organs (glands, hair, and nails)

The three layers of the skin are

Epidermis, Dermis, and Hypodermis

Epidermis

The epidermis uses tightly packed cells that do not absorb or lose water

Stratum Layers

The Stratum Layers are at the very surface of the epidermis and protect the body from microbes

Melanocytes

Melanocytes are specialized cells that produce melanin

Melanin

Melanin is a dark pigment that builds up around the nucleus of each skin cell to protect nuclear DNA from mutations and skin cancer

Dermis

The dermis is the thickest layer of the skin, made up of dense irregular connective tissue and maintains body temperature (thermoregulation)

The dermis reacts to heat by…

The dermis reacts to heat by stimulating sweat glands to allow heat to evaporate and opening blood vessels

The dermis reacts to cold by…

The dermis does not stimulate any sweat glands and constricts blood vessels (vasoconstriction)

Hypodermis (subcutaneous tissue)

The hypodermis (subcutaneous tissue) is made up of connective tissue and adipose (fat).

The hypodermis is…

The hypodermis is an insulator, cushion, and energy reservoir

Merkel Cells

Merkel Cells are few in number and found at the stratum basal layer in the epidermis, they are touch and temperature receptors.

When epithelial cells are cut…

When epithelial cells are cut, they will actively divide to make up for the lost cells.

When the dermis is wounded…

When the dermis is wounded, blood vessels break off and form a scab, that will later break off as damaged tissue is replaced

Doctors classify burns by…

Doctors classify burns using degrees to indicate the depth and severity of the burn