Chapter 7 Integumentary System

Integumentary System

performs many roles; protects the body from harm or acts as a barrier against the external environment.

Functions of the skin

• Acts as a mechanical barrier

• Protects the internal structures and organs from injuries

• Participates in the immune response against invading microbes

• Performs an excretory function

• Acts as a gland by synthesizing vitamin D.

• Performs a sensory role by housing the sensory receptors for touch, pressure, pain and temperature.

• Plays an important role in the regulation of body temperature

Integument or Cutaneous membrane

The skin

Epidermis

outer or surface layer of the skin

Dermis

inner layer of the skin

Anchored to the skin subcutaneous layer

Dermis

Dermatology

The study of the skin and skin disorders

Epidermis

• Outer layer of the skin

• composed of stratified squamous epithelium

• avascular

• Divided into 5 layers - stratum corneum; Stratum lucidum; Stratum granulosum; Stratum spinosum; Stratum basale (germinativum)

Stratum germinativum

•lies on top of the dermis and has a rich blood supply

• Layers continuously divide, producing millions of cells per day

• push older cells up toward the surface of the surface of the epithelium

As cells move away from the dermis...

• the move away from their source of nourishment and start to die

• undergo a process of keratinization

Keratinization

The process where keratin is deposited into the cells that harderns and flattens the cells and makes them water-resistant

Stratum corneum

• The surface layer of the epidermis

• Composed of 30 layers of dead, keratinized cells.

Apocrine glands

One of the sudoriferous (sweat) glands

Ceruminous glands

modified sweat gland found in the external ear canal; secretes cerumen, or ear wax

Cerumen

yellow, sticky, wax-like secretion repels insects and traps foreign material.

Conduction

loss of heat energy as it is transferred from the warm body to a cooler object, such as a heating blanket

Convection

loss of heat energy to the surrounding cooler air. The layer of heated air next to the body is constantly being removed by a fan and replaced by cooler air.

Cutaneous membrane

skin

Dermis

Thick layer of dense connective tissue that lies under the epidermis of the skin

Eccrine gland

type of sweat gland that secretes a watery substance; plays an important role in the regulation of body temperature

Epidermis

outer epithelial layer of skin

Evaporation

loss of heat as water changes from the liquid to the vapor or gas state.

Integumentary System

Organ system that consists of the skin and accessory organs

Keratin

a protein found in the skin, hair, and nails; it hardens the cells and makes them water-resistant

Melanin

pigment responsible for the color of the skin and hair

Radiation

Loss of heat as it leaves a warm object, such as the body, to the cooler air.

Sebaceous glands

exocrine glands located in the skin that secrete sebum

Stratum corneum

Outermost layer of the epidermis

Stratum germinativum

Innermost layer of the epidermis where cell division takes places

Subcutaneous layer

tissue beneath the dermis that contains fat cells

Sudoriferous glands

sweat glands

Thermoregulation

Homeostatic regulation of body temperature by adjustments in the heat-producing and heat-losing mechanisms

Stratum Basale

The deepest of the 5 layers of the epidermis, composed of cuboidal-shaped cells. This layer provides new cells by mitotic cell division.

Stratum Corneum

The horny, outermost layer of the skin, composed of dead flat cells converted to keratin that continually flakes away. The thickness of this layer is correlated with the normal wear and tear of the area it covers. It is thick on the palms of the hands and the soles of the feet but relatively thin over most areas.

Stratum granulosum

one of the layers of the epidermis, situated below the stratum corneum except in the thick skin of the palms of the hands and the soles of the feet where it lies just below the stratum lucidum. Contains visible granules in the cytoplasm of the cells.

Stratum lucidum

one of the layers of the epidermis, situated just below the stratum corneum and present only in the thick skin of the palms of the hands and soles of the feet. Contains translucent eleidin that forms keratin

Stratum spinosum

One of the layers of the epidermis, composed of several layers of polygonal cells. It lies on top of the stratum basale and just beneath the stratum granulosum and contains tiny fibrils within its cellular cytoplasm.

Body temperature

Normal is 98.6°F

Lower in the morning and higher in the late afternoon.

Differs from one part of the body to another

Core Temperature

temperature of the inner parts of the body, like the cranial, thoracic, and abdominal cavities.

Shell Temperature

temperature of the surface areas like the skin and mouth

Thermoregulation

The mechanism whereby the body balances heat production and heat loss. Body temperature is maintained by the balancing of heat production and heat loss.

Most heat loss occurs through the

Skin

80%

The remaining is lost through the

respiratory system(lungs)

Excretory products (urine and feces)

20%

Heat loss occurs by:

• Radiation

• Conduction

• Convection

• Evaporation

Hypothalamus

the thermostat of the body

Sense changes in body temperature and send information to the skin, blood vessels, sweat glands, and skeletal muscles.

Exercise and temperature elevation causes:

the blood vessels to dilate allowing more blood to flow to the skin.