Integumentary System; the Skin

These flashcards cover essential vocabulary related to the integumentary system and skin functions, structures, diseases, and treatments.

Integumentary System

The organ system protecting the body from damage, loss of water, UV radiation, and pathogens.

Epidermis

The superficial, avascular layer of the skin composed of keratinized stratified squamous epithelium.

Dermis

The deeper layer of the skin containing connective tissue, blood vessels, nerves, and sensory receptors.

Hypodermis

The subcutaneous layer beneath the skin that stores fat and connects skin to underlying muscle/bone.

Keratinocytes

The primary cells of the epidermis that produce keratin for waterproofing and protection.

Melanocytes

Cells in the stratum basale that produce melanin to protect against UV radiation.

Stratum Basale

The deepest epidermal layer where continuous mitosis occurs; sits on the basal lamina.

Stratum Corneum

The most superficial layer consisting of 15-30 layers of dead, flattened keratinized cells.

Sebaceous Glands

Glands that secrete oily sebum via holocrine secretion to lubricate skin and hair.

Eccrine Sweat Glands

Widely distributed glands that produce hypotonic sweat for thermoregulation via merocrine secretion.

Apocrine Sweat Glands

Glands in axillary/pubic regions that produce thicker secretions associated with hair follicles.

Melanin

A pigment that determines skin color and protects DNA from UV damage.

Basal Cell Carcinoma

The most common skin cancer; originates in the stratum basale and rarely metastasizes.

Squamous Cell Carcinoma

Skin cancer originating from keratinocytes in the stratum spinosum; can metastasize.

Melanoma

The most dangerous skin cancer; arises from melanocytes and is highly metastatic.

Ringworm

A fungal infection causing a circular itchy rash, often transmitted from mammals.

Cyanosis

A bluish tint to the skin resulting from poor oxygenation or circulation.

Eczema

An allergic inflammatory condition characterized by dry, itchy patches and swelling.

Rule of Nines

A method to estimate the total body surface area affected by burns in increments of 9\%.

Simple Cuboidal Epithelium

Tissue found in the integumentary system responsible for secreting sweat and sebum.

Dense Irregular Connective Tissue

The major tissue type of the reticular dermis providing multi-directional strength.

Arrector Pili

Smooth muscle associated with hair follicles that causes hair to stand up (goosebumps).

Neural Tissue

Tissue distributed throughout the dermis responsible for sensing the environment.

Avascular

A term describing the epidermis, meaning it lacks its own blood vessels.

Thick Skin

Skin with 5 epidermal layers found only on the palms and soles.

Keratin

A fibrous protein that provides structural strength and water-resistance to the skin.

Basal Lamina

The basement membrane foundation that attaches the stratum basale to the dermis.

Dermal Papillae

Finger-like projections of the dermis that increase surface area for epidermal attachment.

Basal Cells

Cuboidal-shaped stem cells that constantly divide to produce new keratinocytes.

Merkel Cells

Specialized sensory cells located in the stratum basale that sense light touch.

Stratum Spinosum

Layer of 8-10 cell sets characterized by a spiny appearance due to desmosomes.

Desmosomes

Intercellular anchoring junctions that hold keratinocytes together in the stratum spinosum.

Glycolipids

Water-repelling lipids produced in the stratum spinosum to make skin waterproof.

Langerhans Cells

Dendritic cells in the stratum spinosum that act as macrophages to engulf invaders.

Stratum Granulosum

Epidermal layer where cells flatten, nuclei disintegrate, and keratin granules accumulate.

Stratum Lucidum

A clear, thin layer of dead cells found only in thick skin between the granulosum and corneum.

Eleidin

A clear, lipid-rich protein found in the stratum lucidum that provides waterproofing.

Cornification

The process of cells filling with keratin and dying as they move to the stratum corneum.

Papillary Layer

The superficial layer of the dermis made of loose areolar connective tissue.

Reticular Layer

The deeper, thicker layer of the dermis composed of dense irregular connective tissue.

Fibroblasts

Cells in the dermis that produce collagen and elastin fibers.

Elastin

Protein fibers in the dermis that provide elasticity and flexibility.

Collagen

Protein fibers in the dermis that provide tensile strength and structure.

Loose Areolar Tissue

Connective tissue found in the papillary dermis and hypodermis.

Adipose Tissue

Fat-storing tissue found in the hypodermis used for insulation and energy storage.

Hemoglobin

A pigment in red blood cells that contributes a pinkish tint to the skin.

Carotene

An orange-yellow pigment found in the skin derived from certain vegetables.

Vitamin D Synthesis

The process where the epidermis produces cholecalciferol from cholesterol upon UV exposure.

Cholecalciferol

Also known as Vitamin D_{3}; the inactive form produced in the skin.

Calcidiol

The intermediate form of Vitamin D produced in the liver.

Calcitriol

The active form of Vitamin D produced in the kidneys to regulate calcium.

Hair Root

The living portion of the hair located beneath the skin surface in the dermis.

Hair Shaft

The visible part of the hair consisting of dead, keratinized cells.

Thermoregulation (Hair)

The use of hair follicles and arrector pili to trap heat; mostly significant in non-human mammals.

Anagen

The active growth phase of hair follicles lasting 2 to 7 years.

Catagen

The transitional phase of hair growth lasting 2 to 3 weeks.

Telogen

The resting phase of hair growth lasting 2 to 4 months before shedding.

Nail Body

The visible part of the nail made of dead, densely packed keratinocytes.

Nail Matrix

The part of the nail root containing actively dividing cells.

Nail Bed

The vascularized tissue beneath the nail body that gives nails a pink color.

Merocrine Secretion

A method of secretion where the cell remains intact and releases products via exocytosis.

Dermcidin

An antibacterial protein found in eccrine sweat.

Holocrine Secretion

A method of secretion where the entire cell ruptures to release its contents (e.g., sebaceous glands).

Exocrine Glands

Glands that secrete their products into ducts that lead to the surface of the skin.

Androgens

Hormones that stimulate sebaceous gland activity, often linked to acne at puberty.

Hair Root Plexus

Nerve endings wrapped around hair follicles that detect movement or contact.

Meissner Corpuscle

A tactile receptor in the papillary dermis that detects light touch.

Pacinian Corpuscle

A lamellated receptor in the dermis that detects vibration and deep pressure.

Nociceptors

Free nerve endings that function as pain receptors.

Thermoceptors

Free nerve endings that detect changes in temperature.

Sympathetic Nervous System

The part of the nervous system that regulates the secretion of sweat glands.

Vasoconstriction

The narrowing of blood vessels in the skin to trap heat inside the body's core.

Vasodilation

The widening of blood vessels in the skin to release heat to the environment.

Metastasis

The process by which cancer cells spread from their original site to other parts of the body.

ABCDE Rule

A mnemonic for diagnosing melanoma (Asymmetry, Border, Color, Diameter, Evolving).

Acne

A condition caused by blocked hair follicles due to overproduction of sebum and keratin.

Propionibacterium

A genus of bacteria that often infects blocked hair follicles, intensifying acne.

Blood Clot

The clinical first response to an injury involving sharp objects to stop bleeding.

Phagocytes

Cells mobilized during wound healing to eat invaders and clear dead tissue.

Granulation Tissue

New tissue and capillaries that grow into a wound area during the healing process.

First-Degree Burn

A superficial burn affecting only the epidermis; causes redness and heals quickly.

Second-Degree Burn

A burn affecting the epidermis and part of the dermis; characterized by swelling and blisters.

Third-Degree Burn

A burn involving the entire thickness of the dermis, damaging nerves and sensory receptors.

Fourth-Degree Burn

The most severe burn, extending through the skin into underlying muscle and bone.

Dehydration (Burns)

The most immediate systemic threat from severe burns due to the loss of the skin barrier.

Scar

Fibrous tissue formed by fibroblasts when cell division cannot keep pace with tissue damage.

Keloid

A raised, hypertrophic scar resulting from the excessive production of collagen.

Stretch Marks

Tears in the dermis that occur when skin expands beyond the capacity of elastic fibers.

Decubitis Ulcer

Also known as a bedsore; caused by prolonged pressure restricting blood flow to bony areas.

Callus

A thickened area of skin caused by repeated friction or abrasion stimulating mitosis.

Corn

A specialized type of callus resulting from localized pressure on the skin.

Sebum

An oily substance that lubricates the skin and has antimicrobial properties.

Hypotonic Sweat

Sweat produced by eccrine glands that is mostly water with minimal solutes.

Dermis Nerves

The structures responsible for detecting stimuli like vibration, cold, and pressure.

Basal Lamina Foundation

The specific structure that connects the epidermis to the papillary layer of the dermis.

Vitamin D Function

Critical for the regulation and absorption of calcium and phosphorus.

Skin Cancer Treatability

Highly treatable when caught early because lesions are visible on the skin's surface.

Fungal Rash

The typical appearance of ringworm, which presents as a circular, itchy lesion.

Autonomic Nervous System

The system that regulates smooth muscles surrounding blood vessels in the skin.

Mitosis in Healing

The process where basal cells increase division rates to replace injured tissue.