skin Flashcards
____ is the body’s largest organ
skin
____ is a vital, complex, diverse, and extensive organ
skin
Skin consists of 2 main layers:
- Epidermis
- Dermis
Superficial epithelial layer
Epidermis
Deep vascular connective tissue layer
Dermis
flat organ classified as a membrane
cutaneous membrane
system consisting of skin and appendages (hair, glands, nails, etc)
Integumentary system
Type of skin that covers most of our body surface, everywhere except palms of hands & soles of feet
Thin skin
Type of skin that does not contain hair, found on soles of our feet and palms of our hands. Friction ridges form fingerprints
Thick skin
____ ____ are created by the projections of the epidermis that lock into the papillary dermis (upward projections of the dermis)
Friction ridges
Most superficial layer of skin composed of several different types of epithelial cells
Epidermis
Epidermis consists of the following 4 types of epithelial cells:
- keratinocytes
- melanocytes
- dendritic cells
- tactile epithelial cells (merkel cells)
Tough fibrous protein that protects the epidermis from mechanical and shearing forces
keratin
_____ constitutes over 90% of cells present in epidermis
keratinocytes
Once keratinocytes have migrated to the outer most layer and flattened out, they are sometimes called _____.
corneocytes
__cytes do not migrate.
melanocytes
type of cell in epidermis that makes granules of pigment called melanin
Melanocytes
pigment that migrates around nucleus of specialized cell to shield DNA from UV radiation by reducing the amount of UV that can penetrate into deeper layers of skin
melanin
type of cell in the epidermis that are branched and play a role in the immune response
Dendritic cells
Type of cell in the epidermis located in the deepest layer of the epidermis near sensory nerve endings and serve as light touch receptors
Tactile (Merkel) cells
5 layers or strata of the epidermis are:
Superficial to deep:
- stratum Corneum
- stratum Lucidem
- stratum Granulosum
- stratum Spinosum
- stratum Basale
Come, Let’s Get Sun Burn!
Type of distinct epidermis layer only found in thick skin
stratum lucidum
Base layer of the epidermis attached to the basement membrane via Rete Pegs and consist of 1 layer of columnar cells
stratum basale
downward projections into the papillary dermis
Rete Pegs
spiny layer of the epidermis where cells are arranged in 8 to 10 layers of irregularly shaped cells. These cells are rich in RNA
stratum spinosum
granular layer of the epidermis that is 3-5 layers thick. Keratinocytes begin keratin formation here
stratum granulosum
release a lipid rich fluid that acts as a water-repellent sealant to reduce water and particle loss/entry
lamellar granules
cells start degeneration, getting further away from the blood supply in this epidermis layer
stratum granulosum
programmed cell death
apoptosis
clear layer of the epidermis ONLY present in thick skin. few layers thick of flattened, dead keratinocytes
stratum lucidum
AKA “horny” layer of the epidermis and is the most superficial layer (15-30 layers thick) composed of dead/dying squamous cells
stratum corneum
refers to time required for keratinocytes to form in the stratum basale and migrate to the skin surface
turnover, or regeneration
Average turnover/regeneration time:
35 days (4-6 weeks)
shortened turnover time will increase the thickness of the ____ _____ layer and may result in callus formation
stratum corneum
As cells migrate from the basal layer to corneum they:
take on more keratin (keratinization)
contains polysaccharide gel that glues the two layers together
basement membrane
____ ____ is the dermoepidermal junction that resists shear forces and creates a partial barrier to some large molecules
Dermoepidermal Junction
sometimes called “true skin” - much thicker than the epidermis and lies beneath it
Dermis
3 functions of the dermis:
- gives strength to the skin
- provides protection against mechanical injury and compression
- Serves as a reservoir area for storage of water and electrolytes
the _____ contains many nerves and nerve endings and is highly vascularized
dermis
Composed of fine collagenous and elastic fibers - dense irregular connective tissue.
Papillary Layer
____ ____ is composed of dermal papillae that project into the epidermis
Papillary layer
____ ____ forms a unique pattern that gives an individual fingerprints and also makes up <20% of the dermis
Papillary layer
Contains dense interlacing white collagenous fibers and elastic fibers to make the skin tough yet stretchable - dense irregular C.T.
Reticular layer
The ____ layer contains many sensory receptors and nerve endings and provides attachment site for skeletal muscle of the face and scalp
Reticular
AKA subcutaneous layer/superficial fascia that lies deep to the dermis and consists of mostly loose fibrous and adipose tissue
Hypodermis
The 3 functions of the Hypodermis are:
anchors skin to underlying tissues (muscle), energy source, thermoregulation
Lack/decreased function of tyrosinase
albinism
7 functions of skin:
- Protection
- Sensation
- Flexibility
- Excretion
- Hormone production
- Immunity
- Homeostasis of body temperature
