ESSENTIALS
Unit
2Integumentary System (Skin)
ESSENTIALS
OF HUMAN
ANATOMY
& PHYSIOLOGY
Integumentary System
�Skin (cutaneous membrane)
�Skin derivatives
�Sweat glands
�Oil glands
�Hairs�Hairs
�Nails
Skin Functions
�Protects deeper tissues from:�Mechanical damage
�Chemical damage
�Bacterial damage
�Thermal damage
�Ultraviolet radiation�Ultraviolet radiation
�Desiccation
�Aids in heat regulation
�Aids in excretion of urea and uric acid
�Synthesizes vitamin D
Skin Structure
�Epidermis- outer layer
�Stratified squamousepithelium
�Keratinized
�Dermis
Dense connective�Dense connective
tissue
Layer of Epidermis
�Stratum basale�Cells undergoing mitosis
�Next to dermis
�Stratum spinosum
�Stratum granulosum
�Stratum lucidum�Occurs only in thick skin
�Stratum corneum�Shingle-like dead cells
Dermis
�Two layers�Papillary layer�Projections called dermal papillae
�Pain receptors
�Capillary loops
�Reticular layer�Reticular layer�Blood vessels
�Glands
�Nerve receptors
Hypodermis
�Deep to dermis
�Not part of the skin
�Anchors skin to underlying organs
�Mostly adipose tissue
Skin Structure
Skin Renewal
Normal Skin Color Determinants�Melanin�Pigment produced by melanocytes
�Melanocytes are mostly in the stratum basale
�Yellow, brown or black pigments
�Genetics and sunlight exposure
�Carotene�Carotene�Orange-yellow pigment in some vegetables
�Hemoglobin�Red coloring (blood cells in capillaries)
�Oxygen content determines the extent of red coloring
Skin Color Variation
Appendages of the Skin
�Sebaceous glands�Produce oil� Lubricate skin
�Kill bacteria
�Most ducts empty into hair follicles
�Activated at puberty�Activated at puberty
Appendages of the Skin
�Sweat glands
�Widely distributed in skin
�Eccrine (most numerous)
� Open via duct to pore on skin surface
�Apocrine
� Ducts empty into hair follicles� Ducts empty into hair follicles
Sweat and Its Function
�Composition�Mostly water
�Some metabolic waste
�Fatty acids and proteins (apocrine only)
�Function�Dissipate excess heat�Dissipate excess heat
�Excrete waste products
�Acidic nature inhibits bacteria growth
�Odor is from associated bacteria
Heat Regulation
Appendages of the Skin
�Hair�Produced by hair bulb
�Consists of hard keratinized epithelial cells
�Melanocytes provide pigment for hair color
Hair Anatomy
�Central medulla
�Cortex surrounds medulla
�Cuticle outer layer�Most heavily keratinized
Associated Hair Structures
�Hair follicle�Dermal and epidermal
sheath surround hair root
�Arrector pili�Smooth muscle
�Sebaceous gland�Sebaceous gland
�Sweat gland
Appendages of the Skin
�Nails
�Scale-like modifications of the epidermis
�Heavily keratinized
�Stratum basale extends beneath nail bed
�Responsible for growth
�Colorless- lack of pigment�Colorless- lack of pigment
Nail Structures
�Free edge
�Body
�Root of nail
�Eponychium- proximal nail fold that projects onto the nail bodyprojects onto the nail body