Integumentary System (Skin)
5 Layers of the Epidermis
*Bottom to Top* Stratum Basale (Germinativum) Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
Functions of the Integumentary System
- covers the body and protects. - maintains body temp. (sweat) - prevents excessive loss of fluids. - contains sensory organs - sythensizes Vitamin D. (steroid)
Skin Color
- is due to Melanin and the *amount* of melanin produced. Blood flow also plays a role. (detemined by dna)
Hair (Pili)
Accessory organ of the skin present on most body surfaces; they are flexible strands made of protein and mostly dead keratinized cells.
Hair Follicle
Area from which hair grows; located in the dermal layer of skin (dermis).
Stratum Granulosum
Layer of the epidermis composed of cells filled with keratin; these are *almost* dead and are pushed to the surface to shed. *Keratin production continues.*
Meissner's Corpuscles
Light touch receptors within the upper dermal layer; light pressure and cold receptors. (papillary dermal)
Hypodermis
Subcutaneous tissue layer beneath the dermis; contains adipose tissue, a connective tissue that includes fat-storing cells and blood vessels.
Sudoriferous Glands
Sweat glands that regulate body temp and excrete waste like ammonia and urea. Made up of Eccrine and Apocrine glands.
Keratin
The fibrous *protein* found in the epidermis that makes skin waterproof and keeps it strong, also found in hair and nails.
Cerumen
Waxy substance secreted by glands located throughout the external auditory canal. (ear)
Hair Root Plexus
Free nerve endings found around hair follicles. Detects movement of hair. (hair receptor)
Apocrine Gland
Branched tubular sweat gland that is located in the *axilla* and genital areas. It secretes sweat that is responsible for human body odor.
Melanocytes
Cells that produce and contain pigment; contributes to skin color and absorbs damaging UV light. (Same amount in all people)
Eccrine (Merocrin) Gland
Coiled Tubular sweat gland that is found throughout the skin of most regions of the body, especially in skin of forehead, palms, and soles; regulates body temperature. 3,000 per Sq inch in palms!
Pacinian Corpuscles
Deep pressure and pain receptors within the deep dermal layer (reticular) and even hypodermis.
Stratum Basale
Deepest epidermal layer made of a single row of cells that undergo rapid cell division.
Reticular Layer
Deepest layer of the dermis that supplies the skin with oxygen and nutrients; contains blood vessels, connective tissue, sweat and oil glands, and hair follicles. Contains Pacinian Corpuscles for sensing deep, constant touch and pressure.
Nails
Hard, clear keratin plates covering phalanges. (fingers)
Epidermis
The outermost, thin layer of skin, which contains proteins and is composed of *5* smaller layers of *stratified squamous.*
Papillary Layer
Wavy outer layer of the dermis in which dermal papillae (fingerprints) project into the epidermis. Some receptors present for sensing light touch.
Axilla
Medical term for the underarm or armpit area.
Ceruminous Glands
Modified sweat glands found only in the external auditory canal that produce cerumen to protect against foreign bodies.
Subaceous Glands
Oil gland connected to hair follicles that secrete sebum to moisten hair and skin. Large #'s in face and neck; NOT present in thick skin. Some open directly to surface of skin.
Integumentary System
Organ system that provides protection for the body and maintains homeostasis. (skin, hair, nails) Made up of Epidermis & Dermis.
Stratum Corneum
Outermost layer of the epidermis, composed of flattened, keratinized, dead cells that slough off daily.
Subcutaneous
Pertaining to below the skin. (Hypodermis)
Melanin
Pigmented insoluble proteins that account for the color of skin; produced in abundance upon exposure to ultraviolet radiation to protect.
Melanin
Pigmented protein produced by the epidermis that protects skin from sun damage and gives skin and eyes their color.
Thick Skin
Skin of only the *palms and soles* which consists of five layers.
Dermis
The thick layer of connective tissue underneath the epidermis of the skin which consists of a papillary layer and reticular layer.
Stratum Spinosum (Spiny Layer)
The thickest layer of *living* cells, it is the layer of the epidermis where cells switch over from mitotic role and keratin begins to be made. Cells begin to die as they move upward.
Stratum Lucidum
Thin, translucent epidermal layer of dead keratinocytes; only present in thick skin.
Arrector Pili
Tiny muscle fibers attached to each hair follicle that cause goosebumps and the hair to stand erect.