Intro to Skin

• Made up of various tissues

• Considered an organ

Functions of the Skin

• Barrier against bacteria

• Prevents excessive loss or absorption of water

• Contains pigments that protect against ultraviolet rays (melanin)

• Relays sensations from surroundings to the central nervous system

• Helps maintain a constant body temperature

• Storage place for water, fats, glucose

• Production of vitamin D3

Composition

• 3 Major layers

  • Epidermis - outer epithelial layers

  • Dermis - middle connected tissue layers

  • Subcutaneous (hypodermis) - deeper adipose region, not considered true skin

Epidermal Layers

• Stratum Corneum - Outermost Layers

  • Keratinized Layer - means the layer is hard and serves as protection

• Stratum Lucidum – only on the palms and the soles of the feet.

  • (Skin is thickest here. Friction occurs most here)

• Stratum Ganulosum

• Stratum Spinosum

• Stratum Germinativum ( or Basal, Basale)

  • Cells divide here and push their way to the top of the epidermis over 2 to 3 weeks

    

Specialized Epidermal Cells

• Keratinocytes – Cells which produce keratin, a protein that makes both skin and hair elastic

• Melanocytes – Located only in the Basal Layer

  • Produces Melanin, a protein that gives colour to the skin, hair, and eyes

• Langerhans Cells - Help other cells of the immune system recognize invading pathogens

  • Easily damaged by UV light

• Merkel Cells - Located in the Basal Layer

  • Detect Touch

Melanin

• Based on the evolutionary advantage of having more absorbing melanin to prevent cell damage

• Amount of melanin present makes for differences in skin color

• Dark skin has more active melanocytes

  • Suntan – comes from the increased activity of melanocytes

    • A protective reaction to too much exposure to UV radiation

    • WEAR YOUR SUNSCREEN!

• Albinos – organisms without melanin

  • White skin, hair

  • Red eyes due to blood passing through vessels of the retina

Dermis

• Lies directly under epidermis

• Connective tissue

• Two Layers of the Dermis:

  • Papillary Layer – Lies directly under epidermis

    • Bumps along the top edge called Dermal Papillae

    • Fingerprints

  • Reticular Layer – deepest part of “true skin”

    • Elastic, connective tissue

    • Forms structure and framework for skin

Characteristics of the Dermis

• Well-supplied with blood vessels, lymph vessels, nerves, and accessory structures

• High number of capillaries

• When these capillaries dilate, blood rushes to the area and the skin reddens – blushing

• Blood vessels come out of the heart and get smaller until they begin to return to the heart

  • Arteries (Largest) → Aterioles → Capilliares (Smallest; where exchanges happens) → Venules → Veins

Subcutaneous Region

• Area below dermis

  • Also called Hypodermis

• Adipose (fat) tissue stored her

• Contains superficial fascia

  • Superficial Fascia is a connective tissue covering over the fat and connects the skin to the underlying bone or deep fascia

• Adipose provides warmth and cushioning for underlying structure

Ringworm

• Fungus – Dermatophyte (Disease is called Dermatophytosis)

  • Same fungus “family” as athlete’s foot: Tinea pedis

• Can appear anywhere on the body

• Red, bumpy, itchy ring

• Very contagious

• Treatments (Tx):

  • Antifungal creams – OTC

  • Antifungal medications from doctor

  • Doctor diagnoses using Wood’s light

    • Special UV light and if it is ringworm, the ring will glow

  • Usually clears up with treatment in one or two weeks

Sweating

• Sweating - releases heat

  • Heat causes vessels in dermis to dilate

  • Blood rushes to skin surface, where heat can be released

  • Water (in the form of sweat from sweat glands) is brought to the surface of skin and evaporates

  • Takes heat with it

Skin Day 2

Skin Cancer

Cancer Vocab

• Malignant = cancerous

  • Invades other tissues and damage is widespread

• Benign = non-cancerous

  • Cells stay put and don’t invade other tissues

• Oma = tumor

• Carcin = Cancerous

• Melan = Melanin

General Info

• Skin cancer incidence increasing

• Ozone layer thinning, more direct UV rays

Cell Type

• Most common type of skin cancer:

  • Basal cell carcinoma (Deepest Layer of Epidermis)

    • Most often found on face, head, neck, and hands

    • Mohs surgery to remove

• Most deadly type:

  • Malignant Melanoma (affects melanocytes)

  • Treatment with surgery - wide margins

• Severity of cancer depends on division

  • Rated as 1 – 5, with 1 being early stage and 5 being severe

• Rank of Skin

  • Fair Skin

  • Blue or green eyes

  • Blistering sunburn before the age of 12

  • High level of sun exposure

  • Genetics

  • Freckles from the sun?

Moles

• Possibly indicates malignant melanoma

  • Look for the following:

    • A – asymmetric shape

    • B – Border that is irregular or diffuse

    • C – Color that is pearly or multicoloured

    • D – Diameter larger than 5 mm (pencil eraser)

    • E – Elevation above the skin

Prevention

• Early detection

• Watch your moles

• Avoid exposure to excessive amounts of sun, especially between the hours of 10:00 and 2:00

• Wear sun protective clothing

• Wear sunscreen

• Australian Campaign:

  • Slip – on a shirt

  • Slap – on a hat

  • Slop – on sunscreen

• DON’T USE TANNING BEDS

• 75% increase in skin cancer incidence

• If in a high risk category, see your dermatologist

Parts of Hair

• Shaft – visible part above skin surface

• Root – part below skin surface

• Hair bulb – expanded portion at base of root

• Follicle – membranous enclosure

• Arrector Pili Muscle – attached to each follicle and contracts as a result of cold or fright – goose bumps

• Nerve receptor sac – wrapped around hair bulb

• Sebaceous gland – located in dermis. Open to hair follicle and secretes substance for natural oil of hair

Hair Facts

• Hair covers entire body except palms of hands and soles of feet

  • Vellus – light colored hair covering most of skin (peach fuzz)

  • Lanugo – hair covering a developing baby in utero

• Visible hair is dead – can be cut, styled without pain

• During pregnancy, hair grows thick and strong. Tends to fall out after labor and delivery due to the trauma to the body

Hair Life Cycle

• Anagen – growth phase

• Telogen – rest period following growth

  • During the rest period, hair becomes weak and may fall out (especially during brushing, etc.)

Nails

• Nail plate composed of Keratin

• No color due to no melanin

• Pink due to capillaries below

Nail Parts

• Nail Bed – groove in which nail plate lies

• Nail Matrix – supporting structure under the plate

• Nail Root – responsible for nail growth

• Lunula – half moon area at base of nail

• Eponchyeum – cuticle

• Proximal Nail fold – fold of skin at base of nail

Nail Facts

• Grow about 1/8 inch per month

• 3 or 4 weeks to grow from root to visible point

• 3 to 5 months to reproduce entirely

• Nail plate is dead tissue which is why you can cut it without pain

Sebaceous Glands

• Oil glands attached to hair follicles

  • Produces sebum

  • Sebum is acidic & prevents skin infections

  • Sebum holds in moisture

  • Source of most acne

  • Present on all parts of body except palms of the hands and soles of the feet

Sweat Glands

• Coiled, tubular glands within the dermis

• Eccrine –

  • High number over entire body

  • Especially numerous on palms, soles of feet, and forehead

  • Passageway for sweat

  • Sweat composed of water and some salts

  • Sweat a response to emotional stress &/or thermal stress

  • Palms and soles respond more to emotional stress

• Apocrine

  • Attached to hair follicles

  • Found mostly in axillary & anogenital region

  • Secrete sweat that contains fatty substances and proteins

  • Secretions may look milky in color

  • If bacteria feed on the secretions, foul odor occurs (body odor)

• Generally start secretions at puberty due to influence of sex hormones

• Lactation/milk/glands are apocrine

• Ceruminous Glands – in the outer ear & secrete cerumen or ear wax

Varicella Zoster/Herpes Zoster

• Virus

• In children, causes Chicken Pox (Varicella Zoster)

• If immune system compromised, causes shingles (Herpes Zoster)

• Must have been exposed to Chicken Pox first to get shingles

Chicken Pox

• Small, itchy bumps

• Rare to have a recurrence

• Immune System suppresses the virus, but it lies hidden in your body

• Was very common until vaccinations began in 1995

• The virus often stays hidden until after age 50

• Lies dormant in cranial and spinal nerves

• Something triggers the virus to become active again

  • Age

  • Exposure to excessive sunlight

  • Lowered immune system (including stress!)

Shingles

• Red, itchy, runny, painful bumps

• Usually on the torso

• Very painful, as the virus is attacking the nerve root

• Rash will clear within 4 to 6 weeks

• Pain may continue for up to 6 months

• May or may not have recurrences

• Anything that suppresses the immune system after initial viral exposure may cause a breakout of shingles…