Anatomy & physiology the unity of
form and function chapter 6
integumentary system - Consists of the skin and its accessory organs; hair, nails, and
cutaneous glands;
Most visible system, more attention paid to this organ system
Inspection of skin, hair, and nails is significant part of physical exam
Skin is the most vulnerable organ; exposed to radiation, trauma, infection, and injurious
chemicals
Recieves more medical treatment than any other organ system
Dermatology - Scientific study and medical treatment of the integumentary system
Skin and subcutaneous tissue - Consists of two layers: epidermis and dermis;
Most skin is 1-2 mm thick
Ranges from 0.5 mm on eyelids to 6 mm between shoulder blades
Functions of the skin - Resistance to trauma
Other barrier functions
Vitamin D synthesis
Sensation
Thermoegulation
Nonverbal communication
Transdermal communication
Transdermal absorption
Epidermis - Keratinized stratified squamous epithelium;
Dead cells at the surface packed with tough protein; keratin
Lacks blood vessels
Depends on the diffusion of nutrients from underlying connective tissue
Sparse nerve endings for touch and pain
Cells of epidermis - Stem cells
Keratinocytes
Melanocytes
Tactile (merkel) cells
Dendritic (langerhans) cells
Stem cells - Undifferentiated cells that give rise to keratinocytes
In deepest layer of epidermis (stratum basale)
Keratinocytes - Great majority of epidermal cells
Synthesize keratin
, Melanocytes - Occur only in stratum basale
Synthesize pigment melanin that shields DNA from ultraviolet radiation
Branched processes that spread among keratinocytes
Tactile (Merkle) Cells - In basal layer of epidermis
Touch receptor cells associated with dermal nerve fibers
Dendritic (langerhans) cells - Macrophages originating in bone marrow that guard
against pathogens
Found in stratum spinosum and granulosum
Stand guard against toxins, microbes, and other pathogens that penetrate skin
Stratum basale - A single layer of cuboidal to low columnar stem cells and keratinocytes
resting on the basement membrane;
Melanocytes and tactile cells are scattered among the stem cells and keratinocytes
Stem cells of stratum basale divide - Give rise to keratinocytes that migrate toward skin
surface
Replace lost epidermal cells
Stratum spinosum - Consists of several layers of keratinocytes
Thickest stratum in most skin; in thick skin, exceeded by stratum corneum
Deepest cells remain capable of mitosis; cease dividing as they are pushed upward
Produce more and more keratin filaments which causes cell to flatten; higher up in this
stratum, the flatter the cells appear
Dendritic cells found throughout this stratum
Named for artificial appearance created in histological section; numerous desmosomes
and cell shrinkage produces spiny appearance
stratum granulosum - 3 to 5 layers of flat keratinocytes
Contain coarse dark-staining keratohyalin granules
stratum lucidum - Only in thick skin
Thin translucent zone superficial to stratum granulosum
Keratinocytes are densely packed with eleidin
Cells have no nucleus or other organelles
Zone has a pale, featureless appearance with indistinct boundaries
stratum corneum - up to 30 layers of dead, scaly, keratinized cells
Form double surface layer; surface cells flake off (exfoliate)
Resistant to abrasion, penetration, and water loss
Keratinocytes - Produced deep in the epidermis by stem cells in stratum basale
Some deepest_____________ in stratum spinosum also multiply and increase their
numbers
form and function chapter 6
integumentary system - Consists of the skin and its accessory organs; hair, nails, and
cutaneous glands;
Most visible system, more attention paid to this organ system
Inspection of skin, hair, and nails is significant part of physical exam
Skin is the most vulnerable organ; exposed to radiation, trauma, infection, and injurious
chemicals
Recieves more medical treatment than any other organ system
Dermatology - Scientific study and medical treatment of the integumentary system
Skin and subcutaneous tissue - Consists of two layers: epidermis and dermis;
Most skin is 1-2 mm thick
Ranges from 0.5 mm on eyelids to 6 mm between shoulder blades
Functions of the skin - Resistance to trauma
Other barrier functions
Vitamin D synthesis
Sensation
Thermoegulation
Nonverbal communication
Transdermal communication
Transdermal absorption
Epidermis - Keratinized stratified squamous epithelium;
Dead cells at the surface packed with tough protein; keratin
Lacks blood vessels
Depends on the diffusion of nutrients from underlying connective tissue
Sparse nerve endings for touch and pain
Cells of epidermis - Stem cells
Keratinocytes
Melanocytes
Tactile (merkel) cells
Dendritic (langerhans) cells
Stem cells - Undifferentiated cells that give rise to keratinocytes
In deepest layer of epidermis (stratum basale)
Keratinocytes - Great majority of epidermal cells
Synthesize keratin
, Melanocytes - Occur only in stratum basale
Synthesize pigment melanin that shields DNA from ultraviolet radiation
Branched processes that spread among keratinocytes
Tactile (Merkle) Cells - In basal layer of epidermis
Touch receptor cells associated with dermal nerve fibers
Dendritic (langerhans) cells - Macrophages originating in bone marrow that guard
against pathogens
Found in stratum spinosum and granulosum
Stand guard against toxins, microbes, and other pathogens that penetrate skin
Stratum basale - A single layer of cuboidal to low columnar stem cells and keratinocytes
resting on the basement membrane;
Melanocytes and tactile cells are scattered among the stem cells and keratinocytes
Stem cells of stratum basale divide - Give rise to keratinocytes that migrate toward skin
surface
Replace lost epidermal cells
Stratum spinosum - Consists of several layers of keratinocytes
Thickest stratum in most skin; in thick skin, exceeded by stratum corneum
Deepest cells remain capable of mitosis; cease dividing as they are pushed upward
Produce more and more keratin filaments which causes cell to flatten; higher up in this
stratum, the flatter the cells appear
Dendritic cells found throughout this stratum
Named for artificial appearance created in histological section; numerous desmosomes
and cell shrinkage produces spiny appearance
stratum granulosum - 3 to 5 layers of flat keratinocytes
Contain coarse dark-staining keratohyalin granules
stratum lucidum - Only in thick skin
Thin translucent zone superficial to stratum granulosum
Keratinocytes are densely packed with eleidin
Cells have no nucleus or other organelles
Zone has a pale, featureless appearance with indistinct boundaries
stratum corneum - up to 30 layers of dead, scaly, keratinized cells
Form double surface layer; surface cells flake off (exfoliate)
Resistant to abrasion, penetration, and water loss
Keratinocytes - Produced deep in the epidermis by stem cells in stratum basale
Some deepest_____________ in stratum spinosum also multiply and increase their
numbers
