Integumentary System (CH. 5) - Anatomy & Physiology

Fingerlike projections of the papillary dermis

-projections contain capillary loops, free nerve endings, and touch receptors (tactile corpuscles -or Meissner's corpuscles)

-in thick skin, they lie on top of demal ridges, which give rise to epidermal ridges

they are collective ridges. Ridges formed by dermal and epidermal folds that enhance grip and sweat pores in ridges create unique fingerprint patterns.

-contribute to sense of touch

Lines in the reticular dermis where collagen fibers run parallel; incisions made parallel to these lines heal better.

Melanin (made by melanocytes) two forms: reddish yellow to brownish black), carotene (yellow-orange pigment) can be converted to vitamin A for vision & epidermal health, and hemoglobin (pinkish hue from blood) due to low levels of melanin.

Cyanosis: blue skin from low oxygenation of hemoglobin. Pallor (blanching or pale color): anemia, low blood pressure, fear/anger. Erythemia (redness): fever, hypertension, inflammation, allergy, burnt. Jaundice (yellow cast): liver disorders. Bruises: clotted blood beneath skin

Warn of insects, protect against trauma, reduce heat loss, and shield skin from sunlight.

-dead keratinized cells of hard keratin

-hair pigements: melanins (yellow, rust, brown, black); trichonsiderin in red hair. Gray/White: decreased melanin production, increased air bubbles in shaft.

Vellus hair: fine, pale body hair-children/females. Terminal hair: coarse, long hair on scalp, eyebrows, and after puberty in axillary and pubic regions, and face/neck of males.

-nutrients & hormals affect growth

Genetic and hormonal factors; hair follicles respond to dihydrotestosterone (DHT), leading to hair thinning.

Two main types of sweat glands, they contain myoepithelial cells-contract upon nervous system stimulation to force sweat into ducts: Eccrine (merocrine) sweat glands, apocrine sweat glands and sebaceous (oil) glands.

Most numerous type. Ducts connect to pores. Thermoregulation-sympathetic nervous system. by producing sweat that cools the body; found abundantly on palms, soles, and forehead.

-secrete 99% water, salts, vitamin C, antibodies, dermicidin (microbe-killing peptide), metabolic wastes.

Located in axillary and anogenital areas; secrete viscous, milky sweat containing fatty substances and proteins, which bacteria break down causing body odor. Larger than eccrine glands w/ ducts emptying into hair follicles.

Widely distributed (not thick skin of palms & soles). Most developed from hair follicles & secrete into hair follicles. Inactive till puberty. secrete Sebum: Oily holocrine secretion, bactericidal (bacteria-killing) properties, softens hair & skin.

Protection, temperature regulation, cutaneous sensation, metabolic functions, blood reservoir, excretion, and hormone synthesis (Vitamin D).

3 barriers: Chemical: skin secretions (low pH and sebum kill bacteria), melanin. Physical: dead kertatinized cells, surrounded by glycolipids block water/water soluble substances. Biological: dendritic cells of epidermis, macrophages of dermis, DNA absorbs UV radiation.

A: Asymmetry (2 sides of the pigmented area do not match) B: Border irregularity (indentations) C: Color variation D: Diameter larger than 6 mm

Partial thickness burns=First-degree: epidermal damage only (redness, swelling, pain). Second-degree: epidermal and upper dermal damage with blisters. Third-degree: full-thickness skin damage, painless due to nerve destruction. Skin color turns gray-white, cherry red, or blackened.

Estimating the extent and severity of burns by dividing the body surface into regions representing 9% or multiples thereof.

They destroy entire skin thickness and nerve endings; treatment includes removal of burned skin, antibiotics, temporary coverings, and skin grafts.

UVB rays convert a precursor in skin to cholecalciferol (vitamin D3), which is then converted in the liver and kidneys to active vitamin D for calcium absorption.

-Several Layers thick

-keratinocytes in this layer=spickey (prickle cells)

-also melanosomes & dendritic cells

-Thin layer

-Cell appearance changes (cells flatten, nuclei & orgelles disintegrate, kertinization begins).

-accumulate granules-water resistant glycolipid that slows water loss

-cells above this layer die-too far from blood supply

-found only in thick skin (hands and pads of feet)

-consists of thin, translucent, band of 2+ rows of clear, flat, dead keratinocytes

cells change by going through this (controlled cell death)

-nucleus and organelles break down

-dead cells slough off as dandruff and dander

-Strong, flexible, connetive tissue

-cells include fibroblasts, macrophages, other white blood cells

-contains nerves, blood vessels, lymphatic vessels

-fibers in matrix bind body together

-contains epidermal hair follicles, oil glands, and sweat glands

-2 layers: papillary, reticular

-superficial layer of areolar connective tissue consisting loose, interlacing collagen & elastic fibers and blood vessels

-lose fibers allow phagocytes to patrol for microorganisms

-makes of 80% of dermal thickness

-consists of dense, fibrous connective tissue (elastic fibers contain stretch-recoil properties)

at the reticular layer. they are dermal folds at or near joints

-visible on hands, wrists, fingers, soles, toes

Striae: silvery-white scars, "stretch marks", extreme stretching causing dermal tears

Blister: from acute, short term trauma, fluid filled pocket that separates epidermal & dermal layers

Hairs/Hairs follicles, nails, sweat glands, sebaceous (oil) glands

-extends from epidermis surface to dermis (considered touch sensory receptor)

-Hair Bulb: expanded area at deep end of follicle. Hair follicle receptor (root hair plexus)-sensory nerve endings that wrap around bulb. Hair Matrix-actively dividing area of bulb that produces hair cells.

Alopecia: hair thinnining (mostly after age 40)

-True (frank) baldness: gentically determined & sex-influened condition

scale-like modifications of epidermis

-protective cover for distal, dorsal surface of fingers & toes

-contains hard keratin (like hair)

-nail matrix: growth

-Arrector pili: small band of smooth muscle attached to follicle ("goose bumps")

-Hair papilla: dermal tissue containing a knot of papillaries that supplies nutrients to growing hair

-Telogen effluvium (TE) is abrupt hair thinning caused by an abandance of hair follicles entering resting phase at the same time (caused by stress, emotional, hormones, dieting, etc.)

other causes: drugs, hypothyroidism, protein-deficient diets

ceruminous glands (lining of external ear canal; secrete cerumen (earwax). Mammary glands.

Overactive sebaceous glands shortly after birth

Insensible Perspiration: normal=sweat glands--500ml/day of unnoticable sweat.

Sensible: if temp rises, dilation of dermal vessels can increase sweat amount to produce 3 gallons of noticable sweat (cool body)

Cold enviro: dermal vessels contrict, skin temp drops to slow passive heat loss

Cutaneous sensory receptors=nervous system

-Exteroreceptors respond to temp and touch (outside stimuli)

-free nerve endings sense painful stimuli

-skin synthesize vitamin D needed for Calcium absorbtion in intestine

-chemicals from keratinocytes can disarm some carcinogens

-Skin can hold up to 5% of total blood volume in body

-excretes nitrous gases & salt in sweat

-Cholecalciferol: precursor inactivated vitamin D3

-Calcidiol: the precursor to the active form

-Calcitriol: active form of Vitamin D that helps absorb calcium from the intestine

-helps modulate immunity, decrease inflammation, & act as an anticancer agent

Basal cell carcinoma: stratum basale cells proliferate & slowly invade dermis & hypodermis (least malignant; most common)

Squamous Cell Carcinoma: involves kertinocytes of stratum spinosum. 2nd most common type

Melanoma: cancer of melanocytes. Most deadly

Damage caused by denaturation of proteins/lipid bilayer, which destroys cells

-immediate threat=dehydration & eletrolyte imbalance (leads to renal shut down & circulatory shock)

-Secondary threat=infection

>25% of body has 2nd-degree burns

>10% of body has 3rd-degree burns

Face, hands, or feet bear 3rd-degree burns