integumentry sstem (lec)

What is the body's outermost protective boundary, primarily composed of the skin and its accessory structures (hair, nails, and glands)?

Integumentary System

Produce the waterproofing protein keratin which protects the skin from external environment, tightly connected by desmosomes

Keratinocytes

Produce pigment through melanin and protects from UV rays, making up 10-25% of cells deep below the epidermis

Melanocytes

• Derived from bone marrow, participate in immune response with Macrophages - key activators of the immune system

Langerhans / Dendritic cells

• Contact a sensory structure called a tactile (Merkel) disc and function in the sensation of touch, found in the deepest layer of the epidermis

Merkel cells

• 25 to 30 layers of flat dead cells filled with keratin and surrounded by lipids continuously shed, creating 75% of the epidermal surface

Stratum corneum

• Thin, clear layer of dead keratinocytes (3-5 layers) present only in the fingertips, palms of the hands, and soles of the feet

Stratum lucidum

• Transition between deeper metabolically active strata and superficial dead cells, contains lamellar granules releasing lipids, last living layer

Stratum granulosum

• 8 to 10 cell layers of keratinocytes held together by desmosomes, providing strength and flexibility and containing fixed macrophages

Stratum spinosum

• Deepest single layer of the epidermis consisting of columnar or cuboidal cells on the basement membrane attached by desmosomes and hemidesmosomes

Stratum basale (stratum germinativum)

• Thick and vascular layer underneath the epidermis made of strong connective tissue housing blood vessels, nerve endings, hair follicles, and glands

Dermis

• Uppermost layer of the dermis composed of fine collagen fibers with uneven dermal papillae providing nutrients, touch, and pain receptors

Papillary layer

• Lower layer of the dermis composed of thick, densely packed collagen fibers and dense irregular connective tissue with oil glands and hair follicles

Reticular layer

• Layer below the skin proper composed mostly of adipose and loose connective tissue that anchors skin, insulates heat, and absorbs impact

Hypodermis / Subcutaneous Layer

• Tough protein structure present on most skin surfaces except palms, palmar digits, soles, and plantar digits

Hair

• Smooth muscles attached to hair root that pull hair upright

Arrector pili

Oil glands located in the dermis around each hair follicle, producing sebum via holocrine secretion on all body surfaces except palms and soles

Sebaceous glands

• Sebum function that seals in water to prevent skin dehydration and dry, cracked skin

Moisture barrier

• Sebum function that keeps hair and skin soft, flexible, and healthy

Lubrication

• Sebum function providing an antimicrobial barrier that inhibits bacterial and fungal growth

Protection

• Exocrine glands distributed on the body surface providing thermoregulation and waste excretion

Sweat glands

• The two main types of sweat glands found in human skin

Eccrine and Apocrine Glands

• Specialized modified apocrine sweat glands located in the skin of the outer ear canal that produce earwax (cerumen)

Ceruminous glands

• Specialized oil glands inside the rim of the eyelids embedded vertically within the tarsal plate that prevent tear evaporation

Meibomian glands

• Small modified sebaceous glands located on the eyelid edge opening into eyelash hair follicles to keep eyelashes flexible

Glands of Zeis

• Milk-producing glands in lactating females that secrete nutrient-rich milk containing antibodies to nourish infants

Mammary glands

• Condition of having additional mammary glands beyond the standard pair

Hypermastia / Polymastia

• Specialized anatomical structure in certain animals that secretes toxic defense chemicals when touched, licked, or eaten

Poison gland

• Special organ at the base of a bird's tail secreting oily fluid for preening, waterproofing, and antimicrobial defense

Uropygial gland (Preen gland)

• Specialized skin organs in animals producing odorous pheromones for territorial marking, communication, and defense

Scent glands

• Modified apocrine sweat glands on eyelid margins producing fluid with IgA and lysozyme for ocular antimicrobial defense

Glands of Moll

• Modified sebaceous glands located in the skin surrounding the anus in certain mammals like dogs

Circumanal Glands (Perianal / atoid glands)

• A hard keratin structure (dead keratinocytes from stratum corneum) corresponding to hooves and claws, which grows from the nail matrix

Nails

• Crescent-shaped area thick with cells protecting the growing nail matrix

Lunula

• Fish integument type with thin living epidermis covered by protective mucus layer, non-keratinized, with dermal scales originating from dermal layer rich in mucous glands to reduce water friction and deter parasites (lacking epidermal scales)

Non-Keratinized Aquatic Integument (Fish)

• Amphibian integument type with very thin, highly vascular skin, minimal keratinization, abundant mucous glands (keep skin moist for gas exchange) and poison glands, lacking scales, claws, or hair

Smooth, Glandular Respiratory Integument (Amphibians)

• Reptile integument type with dry, thick epidermal layer adapted to prevent water loss, epidermal scales or scutes made of tough keratin, glands nearly absent, periodically shedding outer keratinized layer

Heavily Keratinized Dry Integument (Reptiles)

• Bird integument type with thin, flexible skin covered by specialized keratinized outgrowths (contour feathers for outline, down feathers for insulation), scales on lower legs/feet, lacking sweat glands

Feathered Integument (Birds)

• Mammalian integument type with thick multi-layered skin, heavily keratinized stratum corneum, hair for insulation/sensation, diverse glands (sebaceous, sudoriferous, mammary), and keratin appendages (claws, nails, hooves, horns)

Hairy, Glandular Integument (Mammals

Threat to life caused by hot water, sunlight, radiation, electric shock, or acids/bases resulting in catastrophic loss of body fluids, dehydration, fatal circulatory shock, and infection

Burns

• Type of burn involving only the epidermis, causing redness (e.g. sunburn)

First-degree burn

• Type of burn involving the epidermis and upper dermis, characterized by blistering

Second-degree burn

• Full-thickness burn destroying the epidermis, dermis, and often part of the hypodermis

Third-degree burn

• Blueness from deficiency of oxygen in the circulating blood (cold weather)

Cyanosis

• Redness due to dilated cutaneous vessels (anger, fever, embarrassment)

Erythema

• Yellowing of skin and sclera due to excess of bilirubin in blood (liver disease)

Jaundice

• Pale color from lack of blood flow, anemia, low blood pressure

Pallor

• A genetic lack of melanin

Albinism

• A bruise (visible clotted blood)

Hematoma

• Most deadly skin cancer that arises from melanocytes of a preexisting mole

Malignant Melanoma

• Skin reaction caused when tiny muscles connected to hair follicles contract, making hairs stand up

Goosebumps

• What environmental factor primarily induces skin cancer?

UV rays of the sun

• What are the three main types of skin cancer?

Basal Cell Carcinoma, Squamous Cell Carcinoma, and Malignant Melanoma

• Which type of skin cancer is the least malignant, least dangerous, and most common, making up 80% of skin cancers?

Basal Cell Carcinoma

• From which layer of the epidermis does basal cell carcinoma arise before invading the dermis?

Stratum basale

• Where on the body does basal cell carcinoma most commonly appear?

Sun-exposed areas of the face

• What is the growth rate and metastatic potential of basal cell carcinoma?

Slow-growing and rarely metastasizes

• What is the main treatment for basal cell carcinoma, which leads to successful cure in 99% of cases?

Removal by surgery

• Which type of skin cancer is the second most common?

Squamous Cell Carcinoma

• From which specific cells and epidermal layer does squamous cell carcinoma arise?

Keratinocytes of the stratum spinosum

• What are the primary risks if squamous cell carcinoma is not removed?

It grows rapidly and can metastasize to the lymph nodes, which can be lethal

• What are the treatment methods for squamous cell carcinoma?

Removal by surgery or radiation therapy

• What is the most dangerous and most deadly type of skin cancer?

Malignant Melanoma

• From which cells does malignant melanoma arise, and how does it commonly present?

Melanocytes, often arising from a pre-existing mole as a spreading brown-black patch

• What key characteristics make malignant melanoma particularly difficult to treat?

It is highly metastatic and resistant to chemotherapy