What are the components of the integumentary system?
Skin, hair, nails, and glands
Skin functions
maintain homeostasis, regulate temperature, protect underlying tissues, retard water loss, house sensory receptors, synthesize biochemicals, excrete waste, Vitamin D synthesis
The three layers of skin
epidermis, dermis, hypodermis (subcutaneous)
Epidermis
Outer layer of skin whose function is protection, avascular, stratified squamous epithelium, made of 4/5 layers
What are the 5 layers of the epidermis?
stratum corneum, stratum lucidum (found in thick skin only), stratum granulosum, stratum spinosum, stratum basale
Where is thick skin found?
palms of hands and soles of feet
Melanocytes
Cells that produce melanin. These do not determine skin color!
T/F The amount of melanocytes in the body vary greatly from person to person.
False. Generally people have the same number of melanocytes
Melanin
A pigment found in the deep epidermis and underlying dermis that gives the skin its color. It protects deeper cells from UV rays.
The method used to pass melanin to nearby cells
Cytocrine Secretion
What affects skin color?
Genetics, environmental factors (ie. uv exposure), and circulation within dermal blood vessels
If blood vessels are poorly oxygenated, the skin will have a ____________ color
blueish (cyanosis)
This skin color is most likely to result from an excess of carotene in the body or liver disease
yellow (jaundice)
Dermis
Middle layer of skin that binds the epidermis to underlying tissues. Composed of areolar and dense connective tissue. Responsible for giving us unique fingerprints and providing nutrients to the epidermis (it is vascular). Also contains nerve fibers, rece
Hypodermis
the layer of skin beneath the dermis, which serves as a storage repository for fat. Composed of adipose and areolar tissue. This layer contains major blood vessels.
What are the accessory structures of the skin?
hair, nails, glands
Hair
compressed, keratinized cells that arise from hair follicles, the sacs that enclose the hair fibers
What determines hair color
Melanin.
Eumelanin: Dark hair
Pheomelanin: blonde/red
Lack of melanin: White (albinism)
hair follicle
tubelike depression in the skin from which hair develops
hair shaft
The portion of hair that projects above the epidermis. These are composed of dead keratinized cells
Hair follicle layers
-connective tissue root sheath
-glassy membrane (basement membrane)
-external epithelial tissue root sheath
-internal epithelial tissue root sheath
Arrector Pili Muscle
An involuntary muscle fiber attached to the underside & base of the hair follicle. It causes hair to stand on end and goose bumps to appear.
Nails
protective coverings on the ends of the fingers and toes
Nail Plate
Hardened keratin plate that sits on and covers the natural nail bed.
Lunula
The half-moon-shaped, whitish area at the base of a nail. This is the most actively growing area of the nail.
What are the types of skin glands?
Sebaceous (holocrine) and sweat glands (sudoriferous)
Sebaceous Glands
Secrete sebum that waterproofs and moisturizes hair shafts/ skin
Sweat Glands
The glands that secrete sweat, located in the dermal layer of the skin.
eccrine glands
A type of merocrine sweat gland (releases mere liquid) that responds to body temperature. Opens to the skin via a pore.
Apocrine glands
A type of sweat gland that releases liquid and a piece of the cell that responds to stress, sexual arousal. Commonly found in axilla and groin. These ducts open into hair follicles.
The "fake" sweat glands include
Ceruminous : Secrete ear wax
Mammary: Secrete milk
What happens when your body is too hot?
Blood vessels dilate and the sweat glands activate
What happens when your body is too cold?
Blood vessels constrict, shivering begins, and the sweat glands become inactive
inflammation
The body's response to injury wherein the wound becomes reddened, swollen (blood vessel dilation), hot, and painful.
What happens if the cut is superficial?
Cuts are filled by reproducing epithelial cells
blood clot
The conversion of blood from a liquid form to solid through the process of coagulation. Found in the healing process of deeper wounds to the skin.
T/F A scar will develop if the wound is deep enough to trigger extensive production of collagenous fibers.
True
What is considered a deep injury?
An injury that pierces the dermis.