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Regents Biology
The skin, hair, nails, and a variety of glands make up the integumentary system.
The skin is the largest organ in the body.
Integumentary System
Regents Biology
Functions serves as a barrier
against infection and injury
helps to regulate body temperature
removes waste products from the body
provides protection against ultraviolet radiation from the sun
Regents Biology
The Skin made up of two main
layers:
- epidermis (dead outer layer, living inner layer)
- dermis
Beneath the dermis is a layer of fat (hypodermis) and loose connective tissue that insulates the body.
Regents Biology
Epidermis
Dermis
Hypodermis
Hair follicle Sweat pore
Nerves
Muscle
Sweat gland
Fat
Sebaceous gland
Hair Blood vessels
Regents Biology
Cells in the inner (living) layer undergo rapid cell division, producing new cells that push older cells to the surface of the skin.
Older cells flatten and their organelles disintegrate.
Older cells make keratin (a fibrous protein). When these cells die, they form a waterproof covering on the skin’s surface.
The epidermis also produces melanin (brown skin pigment).
Regents Biology
The Dermis inner layer of the skin
contains collagen fibers, blood vessels, nerve endings, glands, sensory receptors, smooth muscles, and hair follicles
contains two major types of glands (sweat glands and sebaceous (or oil) glands
Regents Biology
Cooling and Excretion When sweat evaporates, it cools the body. Sweat also gets rid of wastes from the blood, along
with water. Sebaceous glands produce an oily secretion called
sebum. Sebum spreads out along the surface of the skin and
helps to keep the skin flexible and waterproof.
Regents Biology
Hair Hair covers most body surfaces.
Hair protects the scalp from ultraviolet light from the sun, provides insulation from the cold, and prevents dirt and other particles from entering the body.
Hair is produced by hair follicles (tube-like pockets of epidermal cells).
An individual hair is a column of cells that have filled with keratin and died.