Human Anatomy
The Integument System
Function(s)
1.
2.
3.
4.
Physical protection
Thermoregulation
Excretion
Synthesis of vitamin D3
Structure of Skin
2 layers – epidermis and dermis
A. Epidermis
•
•
•
•
Consists only of epithelial cells
Avascular – no blood supply
No nerve supply
5 distinct layers of epithelial cells
Epidermis
5
4 3
2
1
1. Stratum Germinativum
• Deepest layer, in contact with dermis
• Single layer of cells
• Only layer of epidermis capable of cell
division
• Contain melanocytes
Melanocytes
Melanocytes
Melanocytes
• Capable of producing the brown pigment,
melanin
• Melanin can absorb energy from
ultraviolet (UV) light
• UV light contains high energy photons that
can damage DNA – mutations
• Melanin can prevent damage to DNA,
helps to prevent skin cancer
Melanocytes
2. Stratum Spinosum
• Several layers thick
• Cells of this layer begin to produce keratin
• Keratin is a water-insoluble protein that
protects the body from water
2. Stratum Spinosum
3. Stratum Granulosum
• Multilayer and cells become compressed
• Keratin crystallizes into granuoles within
the cytoplasm
• Cells are metabolically dead
3. Stratum Granulosum
4. Stratum Lucidum
• Clear layer of cells
• Only present in thick skin
• Cells nothing more than a bag of keratin
4. Stratum Lucidum
5. Stratum Corneum
• Multiple layers of flattened, dead cells
• Number of layers depends on region of the
body
• More friction, more layers of cells
Accessory Structures
of the Integument
1. Hair follicles
2. Oil and sweat glands
3. Nails
Skin Color
• Is determined by 3 pigments
1. Hemoglobin – red pigment within rbc
2. Melanin – brown pigment in
melanocytes
3. Carotene – orange-yellow pigment found
in both epidermal cells and dermal fat
cells
B. Dermis
•
1.
2.
3.
•
Consists of other 3 tissue types
CT
Muscle
Nervous
Has blood supply and nerves
Dermis
Dermis
1. CT adds collagen and elastic fibers
which give strength and stretch
properties
Dermis
2. Muscle – arrector pili m. which is
attached to shaft of hair follicle
Dermis
3. Nervous – detects light touch, stretch,
deep pressure,vibration and temperature