Chapter 5
The Integumentary System
and Body Membranes
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CLASSIFICATION OF BODY
MEMBRANES

Classification of body membranes
(Figure 5-1)

Epithelial membranes—composed of epithelial
tissue and an underlying layer of connective tissue
 Connective tissue membranes—composed largely
of various types of connective tissue
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CLASSIFICATION OF BODY
MEMBRANES (cont.)

Epithelial membranes


Cutaneous membrane—the skin
Serous membranes—simple squamous epithelium
on a connective tissue basement membrane
• Types


Parietal—line walls of body cavities
Visceral—cover organs found in body cavities
• Examples


Pleura—parietal and visceral layers line walls of thoracic cavity
and cover the lungs
Peritoneum—parietal and visceral layers line walls
of abdominal cavity and cover the organs in that cavity
• Diseases


Pleurisy—inflammation of the serous membranes that line
the chest cavity and cover the lungs
Peritonitis—inflammation of the serous membranes in the
abdominal cavity that line the walls and cover the abdominal organs
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CLASSIFICATION OF BODY
MEMBRANES (cont.)

Epithelial membranes (cont.)

Mucous membranes
• Line body surfaces that open directly to the exterior
• Produce mucus, a thick secretion that keeps the
membranes soft and moist
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CLASSIFICATION OF BODY
MEMBRANES (cont.)

Connective tissue membranes

Do not contain epithelial components
 Produce a lubricant called synovial fluid
 Examples are the synovial membranes
in the spaces between joints and in the lining
of bursal sacs
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THE SKIN

Structure (Figure 5-2)—two primary layers called
epidermis and dermis

Epidermis
• Outermost and thinnest primary layer of skin
• Composed of several layers of stratified squamous epithelium
• Stratum germinativum—innermost layer of cells that continually
reproduce; new cells move toward the surface (Figure 5-3)
• As cells approach the surface, they are filled with a tough,
waterproof protein called keratin; eventually cells flake off
• Stratum corneum—outermost layer of keratin-filled cells

Skin pigment—deepest epidermal layer is responsible for
production of pigment, which gives color to the skin
• The brown pigment melanin is produced by specialized cells
in this layer
• Blisters—caused by breakdown of union between cells
or primary layers of skin
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THE SKIN (cont.)

Structure (cont.)

Dermal-epidermal junction—specialized area between two
skin layers
 Dermis
• Deeper and thicker of the two primary skin layers and
composed largely of connective tissue
• Upper papillary layer of dermis characterized by parallel rows
of tiny bumps called dermal papillae
• Ridges and grooves in dermis form pattern unique to each
individual


Basis of fingerprinting
Improves grip for tool use and walking
• Deeper reticular layer of dermis filled with network of tough,
interlacing, collagenous and stretchable elastic fibers


Number of elastic fibers decreases with age and contributes
to wrinkle formation (Figure 5-4)
Dermis also contains nerve endings, muscle fibers, hair follicles,
sweat and sebaceous glands, and many blood vessels
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THE SKIN (cont.)

Accessory structures of the skin

Hair (Figure 5-5)
• Soft hair of fetus and newborn is called lanugo
• Hair growth requires epidermal tubelike structure
called hair follicle
• Hair growth begins from hair papilla
• Hair root lies hidden in follicle and visible part of hair
called shaft
• Arrector pili—specialized smooth muscle that
produces “goose bumps” and causes hair to stand
up straight
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THE SKIN (cont.)

Accessory structures of the skin (cont.)

Receptors (Figure 5-2)
• Specialized nerve endings—make it possible for skin
to act as a sense organ
• Meissner’s corpuscle—capable of detecting light
touch
• Pacini corpuscle—capable of detecting pressure
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THE SKIN (cont.)

Accessory structures of the skin (cont.)

Nails (Figure 5-6)
• Produced by epidermal cells over terminal ends
•
•
•
•
of fingers and toes
Visible part is called nail body
Root lies in a groove and is hidden by cuticle
Crescent-shaped area nearest root is called lunula
Nail bed may change color with change in blood flow
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THE SKIN (cont.)

Accessory structures of the skin (cont.)

Skin glands
• Types
Sweat or sudoriferous
 Sebaceous
• Sweat or sudoriferous glands
 Types

– Eccrine sweat glands
– Most numerous, important, and widespread
of the sweat glands
– Produce perspiration or sweat, which flows out
through pores on skin surface
– Function through life and assist in body heat
regulation
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THE SKIN (cont.)

Sweat or sudoriferous glands (cont.)
 Types
– Apocrine sweat glands
• Found primarily in axilla and around genitalia
• Secrete a thicker secretion quite different from
eccrine perspiration
• Breakdown of secretion by skin bacteria produces
odor

Sebaceous glands
 Secrete
oil or sebum for hair and skin
 Level of secretion increases during adolescence
 Amount of secretion is regulated by sex hormones
 Sebum in sebaceous gland ducts may darken
to form blackhead
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THE SKIN (cont.)

Skin cancer (Figure 5-7)


Types
• Squamous cell carcinoma
• Basal cell carcinoma
• Malignant melanoma
• Kaposi sarcoma
Causes
• Genetic predisposition
• Sun's ultraviolet (UV) radiation damages skin cell
DNA, causing mistakes during mitosis
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THE SKIN (cont.)

Skin cancer (cont.)

Squamous cell carcinoma
• Common type of skin cancer
• Slow growing
• Lesions begin as painless, hard, raised nodules
• Will metastasize
 Basal cell carcinoma (most common type of skin cancer)
• Originates in cells at base of epidermis—often on upper face
• Lesions begin as small raised areas that erode in center, bleed,
and crust over
• Less likely to metastasize than other skin cancer types
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THE SKIN (cont.)

Skin cancer (cont.)

Malignant melanoma
• Most serious form of skin cancer
• May develop from benign, pigmented moles
or excess UV radiation
• Incidence in the United States is increasing
• ABCD rule of self-examination
(Table 5-1)
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THE SKIN (cont.)

Functions of the skin


Protection—first line of defense against:
• Infection by microbes
• Ultraviolet rays from sun
• Harmful chemicals
• Cuts and tears
Temperature regulation
• Skin can release almost 3000 calories of body heat per day

Mechanisms of temperature regulation
– Regulation of sweat secretion
– Regulation of flow of blood close to the body surface
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THE SKIN (cont.)

Functions of the skin (cont.)

Sense organ activity
• Skin functions as an enormous sense organ
• Receptors serve as receivers for the body, keeping
it informed of changes in its environment
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THE SKIN (cont.)

Burns

Treatment and recovery or survival depend on total
area involved and severity or depth of the burn
 Body surface area is estimated using the “rule
of nines” (Figure 5-8) in adults
• Body is divided into 11 areas of 9% each
• Additional 1% located around genitals
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THE SKIN (cont.)

Burns (cont.)

Classification of burns (Figure 5-9)
• First-degree (partial-thickness) burns—only the surface
layers of epidermis involved
• Second-degree (partial-thickness) burns—involve the deep
epidermal layers and always cause injury to the upper layers
of the dermis
• Third-degree (full-thickness) burns—characterized
by complete destruction of the epidermis and dermis
 May involve underlying muscle and bone
 Lesion is insensitive to pain because of destruction
of nerve endings immediately after injury—intense pain
is soon experienced
 Risk of infection is increased
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