Skin/Integumentary System

How much does the skin cover?

1.6 to 1.9 m2 in avg adult

What is the body’s largest organ?

Skin

What is the structure of the skin?

• Cutaneous

• epidermis

• dermis

• hypodermis

What is considered skin?

• appendage

• hair

• nail

• skin glands

Keratinocytes

structural elements of outer skin

• 90% of cells

Melanocytes

contribute to skin colour + filter UV light

• 5% of skin

Epidermal Dendritic Cells

role in immune response

• branched antigen-presenting cells

• are Langerhans cells

Tactile Epithelial Cells / Merkel Cells

forms light touch receptors

• attach to sensory nerve endings

Stratum Corneum / Corneocytes (horny layer)

barrier to water loss & many environmental threats

• most superficial layer

• dead cells filled w/ keratin (barrier)

turnover/ regeneration time

time required for EPIDERMAL cells to form in stratum basale

• migrates to skin surface

• 35 days

Growth factor

regulates epidermal growth & repair

• hormones signal tissue repair

shortened turnover time

• ↑ thickness of stratum coronium

• = callus formation

• 10 to 12 % of all cells in stratum coronium ⇉ mitosis

lamellar corpuscles / pacini corpusle

sense of deep touch, pressure & vibration

Dermo epidermal junction

Partial barrier to the passage of some cells & drugs

• basement membrane= fibrous elements + polysaccharides gel

• gel (glue) attaches the epidermis to dermis

tactile corpuscle/ meissner corpuscle

detecting light touch

• slight pressure

Dermis / corium

• middle layer

• true skin

• thicker than epidermis

• gives strength to skin

• reservoir= water + electrolytes

• sudoriferous (sweat) & sebaceous glands

• blood vessels

• sensory receptors

• rich vascular supply = temperature regulation

Nociceptors

pain, temperature, itch& tickle

Thermo receptors

hot & cold

sensory receptors

• meissners corpuscle/ tactile corpuscle

• pacinian corpuslce / lamellear corpuscle

• nociceptors

• thermoreceptors

exteroceptors

body surface

• merkle disk

• meissner

• ruffini

• krause end bulb

• free nerve endings / nociceptors

• hair root plexus

Where is thick skin found?

surfaces of the palms & soles of feet

Where is thin skin found?

most surface areas of body

Epidermis contains

• Keratinocytes

• melanocytes

• epidermal dendritic cells

• tactile epithelial cells / merkel cells

• stratum corneum/ horny later

• lamellar corpuscles

• dermo epidermal junction

merkle disk

gentle touch

meissner

touch & low frequency vibration

Ruffini

crude & persistent touch

krause end bulb

touch & low freq vibration, textural sensation

free nerve endings (nociceptor)

pain

hair root plexus

detects movement of hair

Pain receptors

free nerve endings = nociceptors

• located on surface of body (exteroceptors)

• In deep visceral organs: viseroceptors

• Brain does not have

Acute/ Fast (A) Pain

superficial injury of trauma

• nerve fibers are [ in skin] + mucous membrane + superficial

• ex., slamming your finger in car door

Chronic/ slow (B)

dull or aching pain in VISCERAL structures

• can be severe = kidney or gallstones

diabetic neuropathy (nerve damage)

uncontrolled diabetes causing a loss of ability of sense pain on certain areas of body surface

• skin of feet

• patients w/ diabetes should be closely monitored for adequacy of cutaneous sensations

referred pain

location far removed from site of injury or disease

• due to mixing/ convergence of sensory nerve impulses from disease organ & skin area

• ex. Heart attack pain , can occur at left shoulder or left arm

Hypodermis

• subcutaneous layer / superficial fascia

• forms connections btwn skin + other structures

• adipose + connective tissue

subcutaneous injections

layer of fat btwn skin & muscle

• insulin, morphine, heparin

melanin

dark pigments in skin, hair & iris of eye

• produced by melanocytes

• forms a cap over the nucleus of Keratinocytes protecting it from UV radiations

Beta- carotene

orange pigments from food can change skin color

hemoglobin

changes in blood flow

• redder: blood flow to skin = ↑ inflammation

• cyanosis: bluish = inadequate oxygenation of blood

Jaundice

yellowish Discolouration of skin & other tissues

ex., white (sclera) of the eye

• accumulation of bile pigments due to improper liver functioning ex., hepatitsis

neonatal jaundice

metabolic + physiological adjustments after birth

• until day 8 in normal birth

• day 14th for premature

• treatment = phototherapy (light)

Functions of Skin

1. Protection

2. Surface Film

3. Sensation

4. flexibility

5. hormone production (vitamin D)

6. execration

7. immunity

What does the function protection do?

• physical barrier to microorganisms

• barrier to chemical hazards

• ↓ potential for mechanical trauma

• prevents dehydration

• protects from excess UV rays exposure (melanin fx)

what does the function Surface Flim do?

• residue + secretion of sweat + sebaceous glands + dead epithelial cells

• antibacterial + antifungal activity

• lubrication

• hydration of skin surface

• buffer of caustic irritants

• blockage of toxic agents

Desquamation

shedding of epithelial elements

what does the function : Sensation do?

acts as a sophisticated sense organ

detects stimuli of

• pressure

• touch

• temperature

• pain

• other general senses

what does the function flexibility do?

permits change in body contours w/o injury

• supple & elastic

what does the function hormone production do?

produces vitamin D

• skin + UV = cholecalciferol (precursor)

• blood transports precursor → liver & kidneys = vitamin D

• vita D = hormone

what does the function excretion do?

filters wastes

• water

• urea/ ammonia / uric acid

what does the function Immunity do?

epidermal dendritic cells trigger helpful immune reactions

• phagocytic cells destroy bacteria

Homeostasis of body temperature

• body temperature

• heat production

  • muscles & liver metabolism

  • direct relationships btwn amount of muscles activity & heat production

• must equal heat lost

  • 80% occurs through skin

  • 20% through mucosa of:

    • respiratory

    • digestive

    • urinary tracts

evaporation

heat energy is expended

• important @ high temp when it is only method

• heat can be lost from skin

radiation

transfer of heat from one object to another w/o contact

• important for cool environmental temps

vasoconstriction

↓ heat loss due to ↓ blood flow across peripheral tissue

vasodilation

↑ heat loss due to ↑ blood flow across peripheral tissue

heat loss

• controlled by -tive feedback loop

• hypothalamus monitors body's internal temp

• vasodilation = if temp ↑ hypothalamus ⇉ sweat glands + blood vessels of skin

• hypothalamus continues until normal body temp

hirsutism

excessive hair growth from drugs

• minoxidil ( Rogaine )

• cyclosporine

Androgenic alopecia

male pattern baldness

• genetic tendency + male sex hormones

nails - Epidermal cells

hard keratin

nail body

visible part of each nail

root

cuticle

• nail in groove hidden by fold of skin

Lunula

moon-shaped white area nearest root

nail bed

layer of epithelium under nail body

• abundant blood vessels

• can be pink under translucent nails

cyanotic nail

bluish colour

• inadequate oxygenation

• due to cardiovascular and/ or respiratory disorders

nail growth

by mitosis in STRATUM BASALE under lunula

• avg. 0.5 mm / week

• 1 inch / yr

onycholysis

separation of nail from the nail bed

eccrine glands

small numerous sweat glands

• over total BSA w/ exception of few small areas

• secretes: perspiration or sweat

• eliminates wastes: urea , ammonia , uric acid

• maintains constant core temp

apocrine glands

body odor

• limited distribution

• located: axillar & around anogenital areas

• NOT involved in regulation of body temp

• = to sexual scent glands of other animals

sebaceous glands

secretes sebum: oily substance that keeps hair & skin soft & pliable

• prevents excessive water loss

• anti-fungal activity

• in DERMIS

  • except in palms & sole

• secretions ↑ in adolescence

  • formation of pimples & blackheads

  • meds such as accutane

acne

over active sebaceous gland + blockage + inflammation of their ducts

Pilosebaceous unit w/ apocrine & eccrine sweat glands

1st degree burn

damaged epidermis & edema

• partial thickness burns

• edema ( fluid trapped = swelling)

2nd burns

damaged epidermis & dermis

• partial thickness burn

3rd degree burn

• deep tissue damage

• to the subcutaneous

Children cycle life

• smooth + unwrinkled + elasticity + flexibility

• few sweat glands

• rapid healing

adults cycle of life

development & activation of sebaceous + sweat glands

Increase

• sweat production

• body odor

• sebum production (acne)

old age cycle of life

wrinkling

decrease in

• sebaceous & sweat gland activity

• less sebum productions

• body’s ability to cool itself

skin cancer

95% of skin cancer = basal cell & squamous cells carcinomas

• very responsive to treatment & seldom metastasize ( spread)

malignant melanoma

metastazie

• tumor produced by melanocytes

• occur on the skin but spread to gastrointestinal tract & brain

• 35, 000 cases reported per year

• 7000 = deaths

kaposi sarcoma

immune deficiencies

ex., AIDS

• producing purple papules → lymph nodes + internal organs

ringworm

tinea = fungal infection of the skin

mycoses

fungal infection of skins ; skin or nails

• also cause infections in mouth, throats lungs, urinary tract

Acne Vulgaris

• self limited disorder

• primarily in teenagers & young adults

• areas of the body that have the greatest # of sebaceous glands

  • face, neck, chest, upper back & upper arm

• external factors

  • oil, greases, dye in hair products

  • detergents, soap , astringents

  • occlusive clothing : turtleneck & bra straps

  • psychological stress

  • diet

type 1 acne

comedones w/ small inflamed papule or pustule

• no scarring present

treatment for type 1 acne

topical therapies, BC pills

type 4 acne

• numerous large cysts

• on face , neck & upper trunk

• severe scarring

treatment for type 4 acne

Accutane tabs

• can cause severe birth defects

treatment for noninflammatory (Comedones) acne

• topical retinoids (tretinoin, adapalene)

• salicylic acid

• azelaic acid

• benzoyl peroxide

• glycolic acid

treatment for inflammatory acne

• papular

• topical retinoids

• benzoyl peroxide

• azelaic acid

• topical antibiotics

• sodium sulfacetamide

• pustular

• oral antibiotics

• nodulocystic

• isotretinoin

• oral corticosteroids

what is the treatment for hormonally- induced acne

• oral contraceptives

• spironolactone

• corticosteroids

• flutamide

acne rosacea

in middle-aged & older adults

• vascular dilation of the central face

  • nose ,cheeks, eyelids & forehead

• unknown cause

• is chronic

treatments for acne rosacea

topical antibiotics: METRONIDAZOLE gel

• benzoyl peroxide

treatment for acne rosacea w/ papular or pustular lesions

TRETINOIN creams

• when it’s unresponsive to other treatment

Allergic contact dermatitis

any dermatitis arising from DIRECT skin exposure to a substance

• allergic = immune response

• irritant- induced = directly damages skin

• common sensation in North America is plant oleoresin

  • poison ivy, poison oak, poison sumac

treatment for allergic contact dermatitis

• corticosteroids: topical or oral in acute phase

• hydrocortisone

• BETNOVATE cream

Psoriasis

red plaques w/ sliver scales

developed as a 2ndary response = triggered by WBC

Plaque psoriasis

symmetrically distributed plaques

• scalp, extensor elbows , knees & back

pustular psoriasis

most severe form

• erythema ( redness) , scaling & sheets of superficial pustules w/ erosions

nail psoriasis

typical abnormality

• pitting w/ colour changes & crumbling of nail

treatments for psoriasis

topical emollients, topical steroids (BETNOVATE) ,TAR