Chapter 5: The Integumentary System Overview

Integumentary System

Includes skin and accessory structures.

Cutaneous Membrane

Another name for the integument.

Accessory Structures

Includes hair, nails, glands, blood vessels.

Epidermis

Outer layer of skin, contains epithelial tissue.

Dermis

Inner layer of skin, consists of connective tissue.

Subcutaneous Layer

Also called hypodermis, insulates and cushions.

Keratinocytes

Cells producing keratin, make up 90% of epidermis.

Melanocytes

Cells producing melanin, protect against UV damage.

Langerhans Cells

Macrophages involved in immune responses.

Merkel Cells

Cells functioning in touch sensation.

Stratum Basale

Deepest epidermal layer, site of cell division.

Stratum Spinosum

Layer with 8-10 keratinocytes, provides strength.

Stratum Granulosum

Layer with non-dividing cells filled with keratin.

Stratum Lucidum

Only present in thick skin, like palms.

Skin Thickness Range

1-5 mm, thinnest at eyelids, thickest at heels.

Skin Weight

Weighs 4.5-5 kg, about 16% of body weight.

Skin Functions

Protection, temperature regulation, sensory perception.

Vitamin D Synthesis

Occurs from cholesterol due to sunlight exposure.

Sloughing Off

Natural loss of skin layers, contributes to dust.

Epidermal Cell Types

Includes keratinocytes, melanocytes, Langerhans, Merkel cells.

Connective Tissue in Dermis

Provides structural support and elasticity.

Epidermal Layer Composition

Composed of keratinized stratified squamous epithelium.

Stratum Corneum

Outermost epidermal layer of dead keratinocytes.

Keratinization

Process of replacing cells with keratin protein.

Callus

Thickened skin from constant friction stimulation.

Dandruff

Excess keratinized cells shed from the scalp.

Thin Skin

Covers all body regions except palms and soles.

Thick Skin

Covers palms, digits, and soles; hairless.

Melanin

Pigment produced by melanocytes in stratum basale.

Eumelanin

Brown to black skin pigment variant.

Pheomelanin

Yellow to red skin pigment variant.

Freckles

Clusters of melanin triggered by sunlight exposure.

Nevi

Benign chronic skin lesions, also known as moles.

Malignant Melanoma

Cancer of melanocytes, aggressive skin cancer.

Vitiligo

Chronic disorder causing depigmentation patches.

Albinism

Congenital absence of pigment in skin and hair.

Dermis

Layer beneath epidermis, composed of connective tissue.

Papillary Region

Upper dermis with areolar connective tissue and touch receptors.

Reticular Region

Lower dermis with dense irregular connective tissue.

Stretch Marks

Tears in dermis from excessive stretching.

Lines of Cleavage

Tension lines indicating collagen fiber direction.

Sebaceous Glands

Oil glands in the dermis associated with hair follicles.

Sudoriferous Glands

Sweat glands located in the dermis.

Dermal Papillae

Small projections in papillary region containing capillaries.

Epidermal Ridges

Contours from dermal papillae; form fingerprints.

Collagen Ridges

Accumulated collagen fibers creating epidermal speed bumps.

Dermis

Skin layer primarily composed of collagen fibers.

Fibroblasts

Cells producing collagen; active during skin injury.

Subcutaneous Layer

Hypodermis; attaches skin to underlying tissues.

Pacinian Corpuscles

Sensory receptors detecting pressure in skin.

Specialization of Layers

Multiple skin layers allow for functional adaptations.

Temperature Stability

Dermis maintains body temperature through regulation.

Sensory Receptors

Detect various tactile sensations in skin.

Merkel Discs

Receptors for light touch located superficially.

Meissner Corpuscles

Sensory receptors for light touch in dermis.

Hair

Composed of dead keratinized epidermal cells.

Keratinization

Process where hair cells become keratinized.

Hair Shaft

Part of hair above the skin surface.

Hair Follicle

Structure below skin level housing hair root.

Sebaceous Gland

Oil gland merging with hair follicle for hydration.

Hair Root

Deepest part of hair; living epithelial cells.

Epithelial Sheath

Partially keratinized cells protecting hair root.

Dermal Sheath

Fully keratinized layer; tough protective covering.

Types of Hair

Includes lanugo, vellus, and terminal hair.

Lanugo

Fine, nonpigmented hair covering fetal body.

Terminal Hairs

Coarse, pigmented hair; visible as facial hair.

Exocrine Glands

Epithelial cells secreting substances like oil.

Sebum

Oily substance preventing dehydration and inhibiting bacteria.

Eccrine sweat glands

Most common sweat glands, cover most body areas.

Apocrine sweat glands

Sweat glands in axilla and groin, secrete viscous sweat.

Thermoregulation

Body cooling process via sweat secretion.

Emotional sweating

Sweating due to stress, fear, or embarrassment.

Ceruminous glands

Modified sweat glands producing earwax in ear canal.

Nail structure

Includes free edge, body, root, and cuticle.

Keratinization

Process of cell death as nails grow.

Physical barrier

Skin's dense tissue and keratin protect against injury.

Biological barrier

White blood cells provide immune defense in skin.

Chemical barrier

Water, acids, and oils protect skin from pathogens.

Microbe protection

Non-pathogenic bacteria occupy space to prevent infections.

Langerhans cells

Skin white blood cells involved in immune response.

Melanin

Pigment blocking UV rays, secreted by melanocytes.

Adipose tissue

Insulates body, protecting against cold temperatures.

Burn

Tissue damage from heat, chemicals, or electricity.

First-degree burn

Affects epidermis, causing mild pain and redness.

Second-degree burn

Destroys epidermis and part of dermis, losing functions.

Homeostasis

Skin's role in maintaining internal stability.

Sweat composition

Eccrine sweat contains water and salt (NaCl).

Cerumen

Waxy secretion from ceruminous glands, protects ear.

Second-degree burn

Destroys epidermis and part of dermis.

Third-degree burn

Full-thickness burn affecting all skin layers.

Epidermis

Outer skin layer, involved in first-degree burns.

Dermis

Middle skin layer, involved in second-degree burns.

Subcutaneous layer

Deepest skin layer, affected in third-degree burns.

Fibroblasts

Cells that secrete collagen for tissue repair.

Basal cells

Epithelial stem cells in the epidermis.

Growth factors

Substances secreted by fibroblasts to recruit cells.

Scar formation

Collagen deposition leading to permanent tissue change.

Epidermal wound healing

Occurs with superficial wounds, no blood vessel damage.

Deep wound healing

Involves dermis, blood vessels, and scar tissue.

Provisional matrix

Temporary scab formed during deep wound healing.