Ch5 integumentary

skin that covers your body

aka cutaneous membrane

Integumentary system is the skin and its derivatives (nails, hair, sweat glands, sebaceous glands)

Epidermis: superficial layer of stratified squamous epithelium

•Dermis: deeper layer of areolar and dense irregular connective tissues

Protection

•Selective permeability

•Temperature regulation

•Dilation of dermal vessels releases heat, constriction conserves heat

•Metabolic regulation

•Vitamin D₃ (cholecalciferol) is produced by some skin cells and converted to calcitriol by the kidneys

•Calcitriol is a hormone involved in calcium homeostasis

•Immune defense

•Epidermal dendritic cells help initiate immune responses

•Sensory reception

•E.g., tactile cells stimulate sensory nerve endings in response to touch

•Secretion

•Sweating; lubrication of hair and skin with sebum

Stratum basale

Stratum spinosum

Stratum granulosum

Stratum lucidum

Stratum corneum

Hemoglobin: blood pigment; red

Melanin: pigment produced by melanocytes

•Increases with exposure to ultraviolet radiation

two types of melanin give people different complexions

•All people have same # of melanocytes

Carotene: yellow-orange pigment from carrot

Hair is white, skin is pale, irises of eyes are pink

Skin appears bluish as a result of oxygen deficiency in circulating blood

Skin appears abnormally red

A bruise

Skin and sclera (white of the eyes) appear yellowish

Skin appears ashen, pale due to white collagen fibers housed within the dermis

also called a mole; localized overgrowth of melanocytes

 yellow or brown spots of high melanocyte activity

proliferation of blood vessels that form a benign tumor

(strawberry-colored birthmarks) are bright red to deep purple; usually appear in childhood

(port wine stains) involve larger dermal vessels and may last a lifetime

 folds of epidermis and dermis on fingers, palms, soles, and toes; increase friction for grasping

Papillary layer: superficial; adjacent to epidermis

-areolar connective tissue

Dermal papillae are projections of the dermis toward the epidermis. contain capillaries that supply nutrients to the epidermis and also contain sensory receptors

•Reticular layer: deeper and thicker layer

dense irregular connective tissue

blood vessels, glands, hair follicles, and nerves

striae

innervation-Nerve fibers are extensively dispersed in dermis

•Monitor sensory receptors, Control blood flow, glandular secretion

•Vasoconstriction (narrowed diameter of vessels) reduces blood flow to skin, helps conserve heat

•Vasodilation (widening diameter of vessels) increases blood flow to skin, helps release heat

whitish free edge

pinkish nail body

nail root - covered by the skin nail body covers a layer of epidermis called the nail bed

Nail matrix: thickened growing part of the nail bed

Lunula: white semilunar proximal area of nail body caused by thickened

Nail folds overlap the lateral and proximal edges

eponychium (cuticle) is a narrow band of epidermis that extends from the margin of the nail onto the nail body hyponychium is a region of thickened stratum corneum over which the free edge of the nail projects

Lanugo: found on fetus

Vellus: fine and nonpigmented, on most of body

Terminal hair: coarse and pigmented

•Hair bulb: deep swelling of epithelial cells where hair originates

•Hair root: portion that is deep to skin surface

•Hair shaft: portion that extends beyond skin surface

Hair production occurs at hair matrix

Medulla: core of loose cells, air spaces

Cortex: several layers of hardened, flattened cells

Cuticle: outer coating

A hair follicle surrounds each hair

•Wall has connective tissue root sheath and epithelial tissue root sheath

Respond to emotions and cold temperatures

"goose bump"

Anagen phase: active growth at hair bulb

Catagen phase: brief regression period (cell division ceases, follicle shrinks)

Telogen phase: resting phase; usual phase when hair is shed

hair thinning

 (excessive hairiness) is commonly caused by excess androgens

•Sweat (sudoriferous) glands: produce watery solution

-Merocrine and apocrine

•Sebaceous glands: produce oily secretions

(between secretory cells) respond to sympathetic stimulation; contract to squeeze the gland so secretions are released

release secretions (via exocytosis)

Secretion is 99% water(sweat)

•Thermoregulation

•on palms of hands, soles of feet, and forehead

secrete into hair follicles at the armpits, nipples, groin and anus

•thick, cloudy, and composed of proteins and lipids

•Bacterial growth = odor

Holocrine glands that secrete oily sebum

inactive during childhood

apocrine glands located in external acoustic meatus

•Secretion mixes with sebum and keratinocytes to produce cerumen

•trap small insects, provides lubrication to eardrum, and contains antimicrobial lysozyme

Skin cancer, •most common, least dangerous

•Starts in stratum basale

Skin Cancer Starts in stratum spinosum

most deadly

•Starts from melanocytes (usually in a mole)

cuboidal to low columnar attached to basement membrane

Cell types:

•Keratinocytes: produce tough keratin protein, water resistant

•Melanocytes: produce melanin

•Tactile cells: sensitive to touch

Cytoplasm fills with keratin filaments

•Keratohyalin granules involved in keratinization process

•Lamellar granules help form water barrier

(found only in thick skin)

 filled with eleidin- product of keratin maturation

(2 weeks from basale)(2 weeks at corneum)

interlocking keratinized cells called corneocytes

lack a nucleus

granulosum

myoepithelial

granulation tissue

transepidermal

Vitamin D₃produced by some skin cells and converted to calcitriol by the kidneys

epidermal dendritic cells

phagocytic

eleidin