Integumentary system

Cutaneous membrane

Skin; dry membrane made of keratinized stratified squamous epithelium over connective tissue.

Mucous membrane (Mucosa)

Lines body cavities open to the outside (respiratory, digestive, urinary, reproductive); functions in secretion and absorption.

Serous membrane

Lines closed body cavities; made of simple squamous epithelium and areolar connective tissue.

Parietal layer

Lines the wall of a body cavity.

Visceral layer

Covers the outside of organs.

Serous fluid

Lubricates organs and reduces friction.

Peritoneum

Serous membrane lining the abdominal cavity.

Pleura

Serous membrane surrounding the lungs.

Pericardium

Serous membrane surrounding the heart.

Synovial membrane

Connective tissue membrane lining joints; secretes synovial fluid.

Protection

Protects against mechanical, chemical, bacterial, UV, thermal damage, and water loss.

Temperature regulation

Controlled by sweat glands and blood vessels.

Excretion

Removes water, salts, and metabolic wastes through sweat.

Absorption

Limited absorption of certain substances through the skin.

General sensory organ

Detects touch, pain, pressure, vibration, and temperature.

Vitamin D synthesis

Skin produces vitamin D when exposed to sunlight.

Epidermis

Outer layer of skin made of keratinized stratified squamous epithelium.

Dermis

Dense connective tissue layer beneath the epidermis.

Hypodermis (Subcutaneous layer)

Adipose tissue beneath the skin; insulation, shock absorption, and anchors skin.

Blister

Fluid-filled separation between the epidermis and dermis.

Stratum Corneum

Outermost layer of dead, keratinized cells; sheds every 25–45 days.

Stratum Lucidum

Clear layer found only in thick skin (palms and soles).

Stratum Granulosum

Cells flatten, fill with keratin, and begin dying.

Stratum Spinosum

Cells become stronger as keratin production increases.

Stratum Basale

Deepest epidermal layer; site of active cell division.

Mnemonic for epidermal layers

Come Let's Get Sun Burned (Corneum, Lucidum, Granulosum, Spinosum, Basale).

Keratinocytes

Cells that produce keratin.

Keratin

Tough fibrous protein that waterproofs and strengthens skin.

Melanocytes

Cells that produce melanin.

Melanin

Pigment responsible for skin color and UV protection.

Epidermal dendritic (Langerhans) cells

Immune cells that detect pathogens.

Merkel cells

Touch receptors associated with sensory nerve endings.

Papillary layer

Superficial dermis containing dermal papillae, capillaries, and touch receptors.

Dermal papillae

Increase nutrient exchange and form fingerprints.

Reticular layer

Deep dermis containing collagen, elastic fibers, glands, blood vessels, and pressure receptors.

Collagen fibers

Provide strength to the skin.

Elastic fibers

Provide elasticity to the skin.

Free nerve endings

Detect temperature and light touch.

Nociceptors

Detect pain.

Merkel discs

Detect light touch.

Meissner corpuscles

Detect touch and vibration.

Pacinian (Lamellar) corpuscles

Detect deep pressure and vibration.

Hair root plexuses

Detect movement of hair.

Cyanosis

Blue skin caused by poor oxygenation.

Erythema

Redness caused by fever or inflammation.

Pallor

Pale skin caused by anemia, low blood pressure, or poor circulation.

Jaundice

Yellow skin caused by liver disease.

Hematoma

Bruise caused by blood collecting under the skin.

Sebaceous glands

Oil glands that produce sebum.

Sebum

Oily secretion that softens skin and hair and inhibits bacterial growth.

Eccrine glands

Primary sweat glands responsible for thermoregulation.

Apocrine glands

Sweat glands in the axilla and genital regions activated by stress, pain, and sexual activity.

First-degree burn

Damages only the epidermis; skin is red and painful.

Second-degree burn

Damages epidermis and part of dermis; blisters form.

Third-degree burn

Full-thickness burn destroying all skin layers; white or black and painless.

Critical burn

25% second-degree, >10% third-degree, or any third-degree burn of the face, hands, or feet.

Rule of Nines

Method for estimating total body surface area burned.

Ringworm (Tinea corporis)

Fungal infection of the body.

Tinea capitis

Ringworm of the scalp.

Tinea pedis

Athlete's foot.

Tinea cruris

Jock itch.

MRSA

Antibiotic-resistant Staphylococcus infection.

Impetigo

Highly contagious bacterial infection with honey-colored crusts.

Cold sores

Caused by Herpes Simplex Virus type 1 (HSV-1).

Shingles

Reactivation of Varicella-zoster virus.

Scabies

Infestation caused by itch mites.

Lice

Parasitic insects that infest hair.

Psoriasis

Autoimmune disorder causing rapid skin cell growth and silvery scales.

Basal cell carcinoma

Most common and least malignant skin cancer; arises from the stratum basale.

Squamous cell carcinoma

Arises from the stratum spinosum; can metastasize if untreated.

Malignant melanoma

Cancer of melanocytes; most dangerous skin cancer.

ABCDE rule for melanoma

A = Asymmetry, B = Border irregularity, C = Color variation, D = Diameter >6 mm, E = Evolution (change).

Which epidermal layer undergoes mitosis?

Stratum Basale.

Which epidermal layer is only found in thick skin?

Stratum Lucidum.

Which skin layer is avascular?

Epidermis.

Which glands produce sebum?

Sebaceous glands.

Which sweat glands regulate body temperature?

Eccrine glands.

Which receptor detects deep pressure?

Pacinian corpuscles.

Which cells produce melanin?

Melanocytes.

Most dangerous skin cancer

Malignant melanoma.

Most common skin cancer

Basal cell carcinoma.

Which burn forms blisters?

Second-degree burn.