Integumentary System

Page 110-121

Integument

• Two major components

• A. Cutaneous membrane – is an organ composed of the superficial epithelium or epidermis and the underlying connective tissues of the dermis.

• B. Accessory structures- inclued hair nails, and a variety of exocrine glands

Functions of I system

• A. Protection

• B. Temperature maintenance

• C. Synthesis and storage

• D. Sensory reception

• E. Excretion and secretion

Epidermis

• Layers of the epidermis or strata of thick skin include the

• Stratum Germinathivum

• Straturm spinosum

• Stratum granulosum

• Stratum lucidum

Epidermis

• Stratum Corneum- is the most superficial layer

Epidermis

• Functions • Skin is extremely important to normal physiologic

function secondary to the roles that it plays in maintaining homeostasis.

• The seven chief functions of the skin are as follow: – Regulation of body temperature – Protection – Sensation – Excretion – Immunity – Blood reservoir – Synthesis of vitamin D

Skin

• Structure • Skin is the largest organ of the body. In adults,

the skin covers an area of approximately 2 square meters and accounts for nearly 20% of one's body weight. Its thickness varies from 0.3-4.0 mm depending on the location on the body.

• The skin is composed of three principal parts

– Epidermis • The epidermis is composed of stratified squamous

epithelium and is separated from the dermis by a thin basement membrane.

• The epidermis is not as thick as the dermis and varies in thickness from approximately 0.3 mm on the eyelids to 1.5 mm on the palms of the hands and soles of the feet.

• The epidermis is an avascular structure. Therefore, all gases, nutrients and waste products must diffuse to & from the capillaries located in the dermis.

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Epidermis

• There are four principal cells that compose the epidermis. These cells are as follow:

Epidermis(cont)

• Keratinocytes- Comprise approximately 90% of all epidermal cells. These cells produce a protein mixture known as keratin which helps waterproof and protect the skin.

Epidermis(cont)

• Melanocytes- Comprise approximately 8% of all epidermal cells. These cells produce a group of pigments known as melanin which are responsible for skin, hair and eye color.

Epidermis(cont)

• Langerhans cells- These cells arise from the bone marrow and migrate to the epidermis. These cells play an important role in the immune response.

• Merkel cells- These cells are located in the deepest regions of the epidermis and are associated with sensory neurons and are thought to function in the sensation of touch.

• The epidermis is composed of five layers or strata. These layers from the deepest to the most superficial are:

• Stratum basale

• Stratum spinosum

• Stratum granulosum

• Stratum lucidum

• Stratum corneum

Toe nails and fingernails

Epidermis

Common Disorders