Chapter 6: The Integumentary System

Comprehensive vocabulary flashcards covering the anatomy, cell types, pigments, accessory organs, and clinical conditions of the integumentary system.

Integumentary System

Also known as the cutaneous membrane, it is the largest organ in the human body, consisting of the skin and its accessory tissues like nails, hair, and glands.

Epidermis

The outermost, non-vascularized layer of skin made of keratinized, stratified squamous epithelium.

Stratum Basale

The deepest epidermal layer consisting of a single row of cuboidal or low columnar stem cells that are highly mitotic.

Stratum Spinosum

Known as the 'spiny layer,' where cells are attached by intercellular junctions called desmosomes.

Stratum Granulosum

The 'granular layer' where the process of keratinization begins and cells begin to die as organelles disintegrate.

Stratum Lucidum

A clear, translucent layer found only in thick skin (palms and soles) that contains the protein eleidin.

Stratum Corneum

The most superficial layer consisting of $20$–$30$ layers of dead, interlocking, scaly keratinocytes.

Keratinocytes

The most abundant epidermal cells; they produce keratin for strength and water resistance.

Melanocytes

Cells located in the stratum basale that produce melanin to shield nuclear DNA from ultraviolet (UV) radiation.

Tactile (Merkel) Cells

Sensitive touch cells in the stratum basale that release chemicals to stimulate sensory nerve endings when compressed.

Epidermal Dendritic (Langerhans) Cells

Immune cells located in the stratum spinosum and granulosum that initiate immune responses against pathogens and cancer cells.

Dermis

The deeper layer of skin primarily composed of dense irregular connective tissue containing blood vessels and glands.

Papillary Layer

The superficial region of the dermis containing areolar connective tissue and dermal papillae.

Reticular Layer

The deeper, major portion of the dermis containing large bundles of collagen and elastic fibers.

Lines of Cleavage (Tension Lines)

The predominant orientation of collagen fiber bundles in the dermis; incisions parallel to these heal faster with less scarring.

Hypodermis (Subcutaneous Layer)

Technically not part of the skin, it consists of areolar and adipose tissue, providing insulation, energy storage, and padding.

Hemoglobin

An oxygen-binding protein in red blood cells that imparts a reddish tint to the skin.

Carotene

A yellow-orange pigment acquired from vegetables that is converted into Vitamin A for vision and immune function.

Albinism

A recessive genetic condition where the enzyme for melanin is non-functional, resulting in a lack of pigment.

Friction Ridges

Unique patterns of arches, whorls, and loops on fingers (fingerprints) that increase friction for grasping.

Lanugo

Fine, unpigmented hair found on a fetus.

Vellus

Fine, primary hair found on children and some adult women.

Terminal Hair

Coarser, pigmented hair found on the scalp, eyebrows, and axillary/pubic regions after puberty.

Arrector Pili Muscle

A smooth muscle attached to the hair follicle that creates goosebumps to trap air for insulation.

Lunula

The whitish, semilunar area at the proximal end of the nail body.

Merocrine (Eccrine) Glands

The most numerous sweat glands that produce a secretion comprising $99\%$ water for thermoregulation.

Apocrine Glands

Sweat glands in axillary and pubic regions that produce a viscous secretion which causes body odor when acted upon by bacteria.

Sebaceous Glands

Glands that produce sebum, an oily lubricant that is bactericidal.

Ceruminous Glands

Modified sweat glands in the ear canal that produce cerumen (earwax) to trap dust and repel insects.

Vitamin D3 (Cholecalciferol)

Synthesized by the skin for metabolic regulation; essential for calcium and phosphate absorption in the small intestine.

Vasoconstriction

The narrowing of blood vessels to shunt blood away from the surface and conserve body heat.

Vasodilation

The widening of blood vessels to bring blood to the surface to release heat.

Second-Degree Burn

A burn involving the epidermis and part of the dermis

Third-Degree Burn

A burn destroying the epidermis, dermis, and hypodermis;

Rule of Nines

A tool used to estimate the percentage of the body burned; for example, the Head equals $9\%$ and the Trunk equals 36%.

Basal Cell Carcinoma

The most common and least dangerous type of skin cancer, originating in the stratum basale.

Malignant Melanoma

The most deadly and aggressive skin cancer, arising from melanocytes.

ABCDE Rule

A diagnostic tool for melanoma: Asymmetry, Border (irregular), Color (varied), Diameter (over $6\text{ mm}$), and Evolving.

Second-Degree Burn Symptoms

redness, pain, and blisters.

Third-Degree Burn Symptoms

Loss of nerves. The primary threat to life is dehydration (loss of fluids), followed by infection.

First-Degree Burn

Epidermis damage only

First-Degree Burn Symptoms

Redness and pain (e.g., mild sunburn).