Basic Skin Functions
 Integumentary: “covering”
 Functions:
 Protect deeper tissues from:
 Mechanical damage
 Chemical damage
 Bacterial damage
 UV radiation
 Thermal damage
 Dessication damage(drying out): contains waterproofing keratin
 Aids in excretion of urea and uric acid (through sweat)
 Synthesizes Vitamine D: Modified cholesterol molecules in skin
covered to vitamin D by sunlight
 Insulate and cushions the deeper body organs
 Regulating heat loss from the body surface
Structure of the skin
 Dermis:
 Thicker than epidermis
 Two main layers:
1. Papillary layer: The upper dermal region. It is uneven and has finger
like projections from its superior surface= Form fingerprints, contains
sensory nerve endings
2. Reticular layer: The deepest skin layer. It contains blood vessels,
sweat, oil glands and hair follicles
 Sebaceous Gland: Oil gland. Are found allover the skin, except on the palms of
the hands and the soles of the feet.
 Subcutaneous tissue: It does not considered part of the skin, but it does
anchor the skin to underlying organs.
 Epidermis:
 Superficial layer
 Divided into 5 layers including Stratum corneum: 20 to 30 cell layers thin.
The shinglelike dead cell remnants, completely filled with keratin (water
repellent, exceptionally tough protein)
 No blood vessels
 Made of living and nonliving cells
 Function: Gets nutrients, water, essential minerals from diffusion
 Contain pigments for skin color:
1. Melanin: a pigment which ranges in color from yellow to brown to
black, is produced by specialized cells called melanocytes
2. Carotene: an orange-yellow pigment, can be found in carrots
3. Hemoglobin: pigment in red blood cells
Appendages of the skin
 Cutaneous glands
 Exocrine glands that release their secretions to the skin surfca via ducts
1. Sebaceous glands = oil glands, produce sebum (a mixture of oily
substances and fragmented cells, contains chemicals that kill bacteria)
2. Sweat glands: also called sudoriferous glands
a. Eccrine glands: far mumerous and are found all over the body.
Produce sweat (acidic)
Heat regulation – nerve ending that causes sweat
secreation
b. Apocrine glands: confied to axillary and genital areas of the body
Ducts empty into hair follicles
Fatty acids and proteins that can be a food source for
bacteria
 Hair and hair follicles
 Hair shaft: the part projecting from the surface of the scalp or skin
 Hair follicles:
a. Epidermal sheath: Epithelia tissue that forms the hair
b. Dermal sheath: dermal connective tissue, supplies blood
vessels to the epidermal portion
c. Arrector pili: small bands of smooth muscle cells, connect each
side of the hair follicle to the dermal tissue. When contracted,
these cause hair to stand up on end
 Nails
 Scale-like modifications of the epidermis
 Heavily kerationized
 Lack of pigment makes them colorless