Appendages• (1) Cutaneous glands – all exocrine glands

– Form in stratum basale and push down into dermis

– (A) Sebaceous (oil) glands

• Everywhere but palms and soles

• Most ducts empty into hair follicles

• Produce sebum – oily substance and fragmented cells

– Keep skin moist

– Have chemicals to kill bacteria

– Production especially stimulated

by male sex hormones

– (B) Sweat glands (sudoriferous)

• More than 2.5 million

• 2 types

• Eccrine glands

–All over

–Produce sweat: water, salts, vitamin C, metabolic wastes, lactic acid

»Clear

»Acidic – pH 4-6 - inhibits bacteria

–Opening = pore – directly to surface

–Regulate body temp

–Stimulated by nerve endings

–May lose up to 7 liters on a hot day

• Apocrine glands–Axillary and genital areas–Ducts open into hair follicles–Secrete fatty acids, proteins, and all of

eccrine secretions –Milky/yellowish color–1st stimulated by sex hormones during

puberty–Activated by nerve endings

• (2) Hair/Hair follicles– Hair follicle produces hair

• Epidermal sheath – inner• Dermal sheath - outer

– Root – hair portion in follicle– Shaft – hair on surface

• Medulla – center• Cortex – intermediate• Cuticle - outer

– Highly keratinized dead cells– Color caused by melanocytes in bulb– Arrector pilli – smooth muscle – pulls hair

upright to add an insulating air layer

• (3) Nails– Scalelike modification of epidermis– Keratinized dead cells– Appear pink because of dermal blood supply– Parts

• Free edge• Body• Root• Nail folds – overlapping skin

– Proximal fold – cuticle

• Nail bed – nail matrix – proximal end = nail growth• Lunula – white crescent – over nail matrix

Infections & Allergies• Athlete’s foot – tinea pedis

– Itchy, red peeling – fungal infection

• Boils & carbuncles – inflammations of hair follicles and sebaceous glands

• Cold sores – fever blisters

– Caused by herpes infection

– Blisters itch and sting

– Activated by stress, fear UV radiation

• Contact dermatitis – caused by chemical exposure

– Ex. Poison ivy

• Impetigo– Caused by staph– Pink, water filled, raised lesions– Develop yellow crust and rupture

• Psoriasis – autoimmune disorder– Red lesions covered by dry, silvery scales– Overproduction of skin cells

Skin Cancer

• Benign – does not metastasize (spread)

• Malignant – metastasizes

• Most common cancer in humans (1 in 5)

• Types

• (1) Basal cell carcinoma

– Least malignant – slow growing

– Most comon

– Stratum basale cells invade dermis

– Form small dome shaped lesions w/ a central ulcer

– Common on face

• (2) Squamous cell carcinoma– Stratum spinosum– Scaly, reddened papule (elevation) – shallow

ulcer w/ raised border– Rapid growth – metastasizes to lymph nodes– Common on scalp, ears, hands, lower lip

• (3) Malignant melanoma– In melanocytes– 5% of skin cancers – 50% chance of survival– Spreading brown/black patch– Metastasizes to lymph nodes and blood

vessels

• ABCD Rule – to recognize melanoma– A – asymmetry– B – border

irregularity – not smooth

– C – color – does it contain different colors

– D – diameter – larger than 6mm

Burns• Caused by heat, electricity, UV radiation,

chemicals• Problems:• (1) Allow fluid to seep out (contains proteins and

electrolytes)– May lead to kidney shutdown and circulatory

shock– Must replace fluids

• (2) Infection – leading cause of death w/ burns– Bacteria and fungi may invade

• Determine extent of burns using “Rule of Nines”

– Body is divided into 11 areas (each 9% of body surface) and genital area (1%)

– Critical

• 25% of body w/ 2nd degree

• 10% w/ 3rd degree

• Face/hands/feet w/ 3rd degree

–If on face they may cause swelling and suffocation

• Classified by severity

• 1st degree – only epidermis

– Red, swollen

– Heal w/in 2-3 days

– Ex. Most sunburns

– Aka partial thickness burn

• 2nd degree – epidermis and upper dermis

– Red, blisters

– Regeneration can still occur

– Aka partial thickness burn

• 3rd degree – all of epidermis and dermis

– Not painful – destroys nerve endings

– Gray, white, or blackened

– No regeneration

– Aka full thickness burn

Development• Birth

– Lanugo – downy covering – infant sheds by birth

– Vernix caseosa – white substance produced by sebaceous glands

– Milia – accumulation

of vernix caseosa in

glands which can be

seen through skin

• Adolescence– Becomes oily– Acne

• 20’s – 30’s– Optimal appearance

• Old age– Hypodermis thins = cold intolerance– Thinning = easier bruising– Dries out– Hair – loses luster, graying

• # follicles decreases = thinning hair• Alopecia - baldness