Biology 2320- Chapter 5: Integumentary System (skin)

ABCD rule of Melanoma

Asymmetry, Border, Color, and Diameter

Layers of the integumentary system

Epidemis and dermis

Root hair plexus

Hair follicle receptor; sensory nerve ending around each hair bulb

Melanin (yellow, rust brown, black)

Hair pigments

Keratin

fibrous protein that helps give the epidermis its protective properties.

Burns

heat, electricity, radiation, certain chemicals; causes tissue damage, denatured cell protein and cell death

Statum Lucidum

thin translucent band, consists of rows of clear, flat, dead kertinocytes. Visible only in thick skin.

Tactile (Merkel) cells

touch receptors that expand into the epidermis. Associated with sensory nerve endings.

What are the 5 layers of the epidermis ?

(1) stratum corneum (2) stratum lucideum (3) Stratum granulosum (4) stratum spinosum (5) Stratum Basale

Stratum Corneum

(horny layer) 20 to30 cell layers thick that accounts for up to ¾ of the epidermal thickness. Keratin and thickened plasma membranes of cells protect the skin against abrasion and penetration and glycolipids b/w its cells waterproofs this layer. Barrier against biological, chemical, and physical assaults.

3 Major types of skin cancer

1) Basal Cell Carcinoma 2) Squamous cell carcinoma 3) Melanoma

What are the 2 layers of the dermis?

1. Papillary (superficial) 2. Reticular (Deep) ~ Middle region layer, vascularized, bulk of the integumentary system; fibrous connective tissue. Strong flexible connective tissue layer. Cells include: fibroblasts, macrophages, mast cells and white blood cells. Supplied with nerve fibers, blood vessels, and lymphatic vessels.

Sudoriferous Apocrine sweat glands

Apocrine Glands Glands that have ducts that open into hair follicles ~ Glands that release secretions through ducts at the armpits; groin, anus, nipples that are acted upon by bacteria to produce distinct noticeable odor called pheromones ~ Active after puberty in signaling and communication ~ Larger than eccrine glands and lie deeper in the dermis.

Integumentary System (Function)

Covers the body and protects, waterproofs it from the outside and protects it from injury, infection, excessive heat or cold, and excess water and fluid loss. Provides vitamin D synthesis External covering of the body ~ Provides protection & prevents water loss ~ Regulates body temp ~ Synthesizes Vitamin D ~ Sensation to touch, pressure, temperature & pain ~ Excretes wastes with sweat

Gray/White hair

Decreased melanin production, increased air bubbles in shaft.

Sebaceous Holocrine (oil) glands

Holocrine glands Holocrine Glands that secrete an oily material (sebum) into hair follicles ~ Coats shaft of hair, proivides lubrication & antibacterial activity ~ Activated during puberty ~ Cells accumulate product and rupture (disintegrate) ~ Are plugged in acne

System primarily responsible for preventing water loss

Integument System The integument system (skin and appendages) waterproofs the body from outside and guards against excess fluid loss from inside

3 pigments that contribute to skin color?

Melanin, carotene and hemoglobin

Sudoriferous Merocrine Sweat Glands

Merocrine (ecrine) glands Glands that have ducts that open at the skin surface ~ Most numerous & widely distributed glands ~ Distributed throughout the body except genitalia, nipples, lips ~ Prevalent on palms, soles and forehead

Ceruminous glands

Modified apocrine glands in external ear canal; secrete cerumen (wax); mammary glands

Basal Cell Carcinoma

Most common, least malignant, stratum basale cells (undifferentiated) proliferate and slowly invade dermis and hypodermis. Cured by surgical removal.

Melanoma

Most dangerous; involves melanocytes; highly metastatic and resistant to chemotherapy; treated by wide surgical excision accompanied by immunotherapy

Keratinocytes

Which cells are tightly connected to one another by desmosomes. Arise in the stratum basale and undergo constant mitosis for epidermal growth. They are dead by the time they reach the surface of the skin.

Secondary line of defense in the human body

White blood cells (WBC): Immune response Phagocytosis: Devouring (eat) of bacteria, dead tissue, etc. Inflammation: Systemic responses to remove injurious stimuli and/or response to heal injured tissue Fever: Temp increases when body is trying to fight infection

Stratum Granulosum

consists of 3-5 layers in which the cells flatten. Keratinization begins. Cells flatten, nuclei and organelles begin to disintegrate and begin to accumulate 2 types of granules: keratohyaline granules and the lamellated granules.

Immediate threat of burns

dehydration and electrolyte imbalance leading to renal shutdown and circulatory shock.

Third Degree Burns

entire thickness of skin damaged; gray-white, cherry red, or black; no initial edema or pain (nerve endings destroyed) skin grafting usually necessary

Liposomes

enzymes in skin lotions that can fix damage DNA

Second Degree Burn

epidermal and upper dermal damage; blisters appear

First Degree Burn

epidermal damage ONLY. localized redness, edema (swelling), and pain

Melanocytes

epithelial cells that synthesize the pigment melanin. Found in the stratum basale.

True baldness

genetically determined; sex-linked trait (male pattern baldness)

Physical/Mechanical barrier

keratin and glycolipids block most water and water-soluable substances; limit penetration of skin by lipid-soluble substances (poison ivy)

What are the cells of the epidermis

keratinocytes, melanocytes, epidermal dendritic cells, and tactile cells

Epidermal dendritic (Langerhans) cells

macrophages cells that help activate the immune system; first line of defense against pathogens

Deep Reticular Layer

makes up 80%of the thickness of dermis. Dense fibrous connective tissue, elastic fibers provide stretch-recoil properties.

Skin Cancer

most skin tumors (undifferentiated cells) are benign; primary risk factor is overexposure to UV radiation.

Sebum

oily holocrine secretion (secretion by cell rupture) softens and lubricates the hair and skin, prevents hair from becoming brittle and slows water loss from the skin; has bactericidal action

Keratinocytes

produce fibrous protein keratin; arise in stratum basale; these cells undergo continuous mitosis

Melanin

produced in melanocytes; migrates to keratinocytes where it forms and pigment shields for nuclei (protects DNA from UV light damage); concentrated amounts found in freckles and pigmented moles

Structure of a nail

scale-like modifications of the epidermis on fingers and toes. Hard keratin composition

Collagen Fibers

single most abundant protein in the body

Mammary glands

specialized sweat glands, secrete milk

Epidermis: Stratum Corneum Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Basale

superficial region; epithelial cells; nonvascularized; 4 cell types and 4 or 5 layers

Dermal papillae

superior surface of papillary layer contain capillary loops, non encapuslated free nerve endings (pain receptors) and ecapsulated touch (tactile) receptors (meissners corpuscles)

What are the appendages of the skin?

sweat glands, oil glands, hair and hair follicles, nails

Cutaneous sensation

temperature, touch, and pain; exteroceptors-- respond to stimuli arising outside the body

Excretion

what integumenatary system function has nitrogenous wastes and salt in sweat (ammonia urea, uric acid)

Chemical barrier

which barrier has low pH secretion (acids) and defensins (antimicrobial proteins) retard bacterial activity.

Carotene

yellow to orange, mostly in the palms and soles; Vitamin A precursor (necessary for normal vision); acquired from diet

Thick skin

~ The only place Stratum Lucidum layer is located ~ Covers the palms, fingertips, and soles of the feet

Dermatoglyphics

The science of fingerprint and foot printing identification

Arrector Pilli

The smooth muscle attached to a hair follicle; responsible for goose bumps.

Adipose tissue

Tissue containing stored fat that serves as a source of energy; found in the hypodermis layer

Friction Ridges

Unique patterns of raised epidermal contours of the fingertips, toes, palms & soles Types: ~ Arch ~ Whorl ~ Loop or a combination of the three

Thin skin

What kind of skin covers the rest of the body

Superficial papillary layer

What layer forms the thin superficial, areolar connective tissue in which collagen and elastic fibers form woven mat with small blood vessels.

Hemoglobin

Oxygen carrying pigment of red blood cells. Produce pink or red color skin when concentrated in surface capillaries.

Squamous Cell Carcinoma

Second most common; involves keratinocytes of stratum spinosum; most common on scalp, ears, lower lip, and hands; grows rapidly and metasticizes. Treated by radiation therapy and surgically removed.

Primary line of Defense in the human body

Skin, Mucous, Tears, Mucous, Tears, BBB-Blood brain barrier Skin- Physical and chemical barrier Mucous Membranes & Cilia- Trap irritants and wave them away from lungs to the stomach where they are destroyed. Tears & Saliva- contain enzymes to destroy invaders Blood Brain Barrier (Astrocytes)- Specialized selective filter to keep in the good and keep the bad out.

Hair follicle

Structure that extends from the epidermal surface into the dermis; two-layered wall: outer connective tissue root sheath, inner epithelial root sheath

Hair Functions

Structure that guards the scalp against physical trauma; helps prevent heat loss; protects from sunlight (UV rays);consists of dead keratinized cells; contains hard keratin; more durable than soft keratin of skin

Lines of Cleavage

Tension lines that indicate the predominant direction of collagen & elastic fibers in the reticular layer of the dermis ~ Incision perpendicular to line: Gaping & delayed healing ~ Incision parallel to line: No gap & quick healing

Terminal Hair

The coarse, thick pigmented hairs found on the scalp, beard, armpits and pubic areas of adults; influenced by hormones

Hypodermis

The deepest "subcutaneous layer" located deep to the more superficial dermis layer. ~ Deepest region; anchors to muscles; subcutaneous deep into skin in various regions. ~ Shock absorber and provides thermal insulation ~ Consists mostly of adipose tissue and storage site of most body fat

Hair bulb

The expanded deep end of the hair

Vellus Hair

The fine present hair found on adult females and on children before puberty; not affected by hormones

Cutaneous Plexus

The network of blood vessels that nourishes the hypodermis; also contains collagen fibers that forms cleavage of tension lines.

Alopecia

The normal thinning or complete loss of hair