Skin/Integumentary System

How much does the skin cover?

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