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.