Chap 5- Integumentary System

Integumentary System

consists of the skin, hair, oil and sweat glands, nails, and sensory receptors

Epidermis

the most superficial layer

Dermis

underlies the epidermis

Hypodermis

called subcutaneous layer, deep to the dermis, composed of areolar and adipose tissue

Keratinocytes

most abundant type of cell in epidermis, form tight barrier that prevents substances from entering the body, produces keratin

Melanocytes

found in the basale cell layer, produce melanin that lead to skin pigment

Intraepidermal Macrophages

Langerhan’s Cells, a type of macrophage in the skin that helps protect the body by engulfing bacteria

Tactile Epithelial Cells

Merkel Cell, sensory receptors in the skin that detect light touch and pressure, foind in basale layer

Thin Skin

covers all body regions except the palms, palmar surfaces of digits, and soles

Thick Skin

covers the palms, palmar surfaces of digits, and soles

Layers of Epidermis

Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale

Stratum Corneum

most superficial layer, 20-30 layers of dead cells, anucleate cells filled with keratin, glycolipids in extracellular space

Stratum Lucidum

clear layer, only in thick skin, separates living and dead cells

Stratum Granulosum

4-6 layers of dying cells, lamellar granules, keratohyaline granules

Lamellar Granules

create a permeability barrier to water, facilitate cell adhesion, and contribute to the skin's lipid-rich intercellular material

Keratohyaline Granules

cross-link keratin filaments to create a tight barrier that protects the body from foreign particles

Stratum Spinosum

layers of keratinocytes unified by desmosomes, thick bundles of intermediate filaments made of pre-keratin, melanin and dendritic cells

Stratum Basale

one row of actively mitotic stem cells, produce keratinocytes and melanocytes

Dermis

strong, flexible connective tissue, fibers in matrix bind body together

Papillary Layer

areolar connective tissue

Dermal Papillae

specialized mesenchymal cells that are located at the base of hair follicles and play a key role in regulating hair growth

Epidermal Ridges

friction ridges, make fingerprints

Reticullar Layer

80% of dermal thickness, irregularly arranged fibrous tissue, pockets of adipose tissue, collagen fibersparallel to skin surface

Skin Pigments

melanin is produced by melanocytes in the stratum basale

Pheomelanin

melanin that produces yellow to red hues

Eumelanin

melanin that produces brown to black hues

Hemoglobin

a red pigment in red blood cells

Carotene

a yellow-orange pigment stored in the stratum corneum and adipose tissue

Albinism

congenital disorder, complete or partial absence of pigment in skin, hair, and eyes, defect of an enzyme involved in the production of melanin

Vitiligo

chronic disorder, causes depigmentation patches in the skin, unknown causes, most likely a combination of genetic factor coupled with a disorder of the immune system

Synthesis of Vitamin D

UV rays activate the precursors (calcitriol) that allow vitamin D to be made, aids in the absorption of calcium from foods in GI tract

Trauma of the Skin

sun burn, cancer, and burns

Basal Cell Carcinoma

least malignant, most common, stratum basale cells proliferate and slowly invade dermis and hypodermis, cured by surgical excision in 99% of cases

Squamous Cell Carcinoma

second most common, keratinocytes of stratum spinosum, usually scaly reddened papulae on scalp, ears, lower lips, and hands, metastasizes, treated by radiation therapy and removal

Melanoma

most dangerous, highly metastatic, resistant to chemotherapies

ABCDE Rule

asymmetry, border irregularity, contains several colors, diameter greater than 6 mm, evolving, changes in size, shape, color, and elevation

Burns

tissue damage caused by heat, electricity, radiation, certain chemicals, denatures proteins, kills cells

First Degree Burn

epidermal damage only, localized redness, edema, and pain

Second Degree Burn

epidermal and upper dermal damage, blisters appear

Third Degree Burn

entire thickness of skin involved, skin gray-white, cherry red, or black, not painful because nerve endings are destroyed, skin grafting necessary

Severe Burns

more than 25% of body has second degree burns, more than 10% of body has third degree burns, face, hands, or feet bear third degree burns

Sebaceous Glands

connected to hair follicles

Eccrine Sweat Glands

most numerous, found throughout whole body

Apocrine Sweat Glands

located in hairy skin areas, armpits and groin

Ceruminous Glands

modified sweat glands located in the ear canal