Unit 2 - Integumentary System

General Functions of the Skin

Protection, regulates body temperature, sensory perception, regulates water loss, and Vitamin D production

General Facts of the Skin

contains all 4 primary tissues

Main Structure 

skin (cutaneous membrane) 

Accessory or Associated Structure 

hair, nails, glands 

Epidermis

Most superficial layer, “stratified squamous keratinized (dry) epithelium”, 4 thin skin layers or 5 thick skin layers: Stratum corneum, Stratum lucidum, stratum granulosum, stratum spinosum, stratum basale

Stratum Corneum

• The outermost layer is “dead” because it’s furthest away from nutrients

• Sheds dead cells but is constantly being replaced

Stratum Lucidum 

only in thick skin NOT ALWAYS PRESENT 

Stratum Granulosum

• Cells start to die here

Stratum Basale

• “germination”

• Skin starts @ this layer

• Very top layer is “dead”

Callus 

thickening of skin caused by repeated pressure or friction

Corn

small callus caused by wearing shoes that don’t fit

Skin Markings

“lines, creases, ridges”

Finger prints

friction ridges

freckles

melanized patches 

• Vary w/ heredity + exposure to sun 

moles

elevated patches that are melanized, can be hairy

Aging

• Effects begin to be visible in our 20’s

• stem cell activity declines

• skin becomes thin repair difficult

• tend to feel cold ———> blood supply to dermis declines

• dermis becomes less elastic ————> get wrinkles, drier

• cuts heal slowly

Membrane 

thin sheet like structures that protect parts of the body 

Serous Membrane

• Line body cavities that have no opening to the outside

• Secrete a watery fluid called serous fluid that lubricates surfaces

Mucous Membrane

lines cavities and tubes that open to the outside

Synovial Membrane

• form inner lining of joint cavities 

• Secrete a thick fluid called synovial fluid

Cutaneous Membrane

Skin

Random Things about Skin

• 16% body mass is your skin

• largest organ

• 2 meters

• thickness : 1.5-6 mm

Thin Skin

• 1-2mm on the body 

• 0.5mm on eyelids 

• hairy 

• covers all parts except palms + soles 

• fewer sweat glands, sense receptors 

• More sebaceous glands 

• lacks stratum lucidum 

Thick Skin

• Up to 6mm

• hairless

• covers palms + soles

• has distinct stratum lucidum

• lacks sebaceous glands

• more sweat glands

• sense receptors are densely packed

Cells of Epidermis

Keratinocyte, melanocytes, merkel cells, langerhan cells

Keratinocyte

• 80-90% of all cells in epidermis

• contain protein keratin

• protect + waterproof skin

• constantly shed + replace

Melanocytes

• 8-10% of epidermis

• produce melanin

• absorbs UV light

Merkel Cells

• found in deepest layer of epidermis

• tactile discs that receptors for light touch

• least numerous

Langerhan Cells

• come from red bone marrow 

• participate immune response 

• easily damaged by UV light 

Epidermis appearance

appears translucent when it contains little melanin

White Skin

Appears pink to read

• depends on amount of oxygen content of blood moving

Albinism 

• inherited trait 

• person cannot produce melanin

Cyanotic (blue)

ex. someone has stopped breathing

• depleted oxygen

Jaundice (yellow)

• build up bilirubin (yellow pigment)

• produce when red blood cells get old

• sign of liver disease

Erythema (red)

• inflammation, allergies, emotional state, hypertension, heat exposure

Pallor (paleness)

• low blood pressure

• anemia

• emotional state

Bronzing

• Addison’s disease

• adrenal cortex

Brusing (hematoma)

• blood clot under skin 

• deficiency in Vitamin C 

Leathery Skin

• over exposure

• leads to skin cancer

Herpes

2 Types: Herpes simplex 1 (cold sores) and herpes simplex 2 (genital herpes) 

• pain or itching 

• small red bumps or tiny white blisters 

• ulcer       (caused by a virus)

• scabs 

Leprosy 

Infectious Disease 

• not contagious 

• caused by a bacteria 

symptoms: severe, disfiguring skin sores nerve damage to arms + legs 

Chicken Pox

caused by viral infection

• has a vaccine

Symptoms:

• fever

• loss of appetite

• headache

• tiredness

• raised red bumps (looks like rash)

• itchy

Hair

• covers entire body except palms, soles, lips, nipples

• growth is accompanied by hormone development

• born w all hair follicles

• hair is fastest growing tissue

• keratinized

• hair color depends on amount of melanin

Consists

• Shaft—————→ visible part

• Follice—————→ surrounds root

• Papillae —————→ growing part

• arrector ——————→ muscle that moves hair

Nails

• modification of epidermis

• clear + hard

Parts of nail

nail plate ——> visible

matrix ———→ growth zone

nail flat, spoonlike

iron deficiency 

swollen fingertips

• hypoxemia

• congenital heart defects

oil glands (sebaceous)

• keeps hair soft

• reduce heat loss

• prevent H2O evaporation

• become active during puberty

sweat glands

• help maintain temperature

• most numerous: armpits, forehead, soles, palms 

scent glands

• pheromones

• modified sweat glands

mammary glands

• produces milk

dermatitis

group of inflammatory skin conditions characterized by redness, itching and dryness

dermatitis symptoms

• itchiness

• dry/cracked skin

• blisters

• dandruff

• thickened skin

• small/raised bumps

dermatitis causes

health conditions such as immunodeficiency and parkinson’s disease. The most common cause is allergic reaction to things such as nickel, perfume, or infection. 

acne

skin condition that occurs when hair follicles become plugged with oil and dead skin cells

acne symptoms 

whiteheads 

blackheads 

small red bumps

pimples

acne causes

• excess oil

• clogged hair follicles

• bacteria inflammation

tinea

fungal infection of the skin caused by dermophyte fungi (ringworm)

tinea symptoms

• ring shaped, red lesions

• itching

• scaliness

• blisters

• discoloration of skin + nails

tinea causes 

• direct contact with people who have it

• sharing towels/clothes 

• playing contact sports 

impetigo

inflammatory skin infection that turns blister into weeping spots. common 4 children

impetigo symptoms

• reddish sores

• contagious

• itchy or sore

• scarring may occur

impetigo causes

• bacteria

• staphulococcus aureus 

• streptococcus pyogenes 

urticaria

red or skin-colored bumps

urticaria symptoms

• raised itchy bumps

• “blanching”

• mild to severe itching

urticaria causes

allergic foods

pollen

infections

insect bites + stings

shingles

viral infection that causes rash anywhere on body

shingles symptoms

• fever

• headache

• itching

• fatigue

• pain, burning, tingling

shingles causes

• varicella zoster virus

hidradenitis suppurativa

chronic skin condition that causes painful recurrent boils + abscesses

hidradenitis suppurativa symptoms

• blackheads 

• lumps

• bumps

• sores

• tunnels 

hidradenitis suppurativa causes

• when hair follicles become blocked, it’s connected to hormones + genetics

eczema

a dry skin disease that causes red, itchy, and inflamed skin

eczema symptoms 

• dry skin 

• sensitivity 

• itchiness

eczema causes

• genetics

• dry environments

• salt water

• fragrance

• harsh chemicals

• itching

Laceration

cause: tissue tearing; caused by blunt force

healing: tend to have jagged edges which scar more than an a straight-edge incision

Abrasion

Causes: skin is rubbed off by a rough surface; “road rash” 

Healing: little to no scarring depending on depth 

Avulsion

causes: skin catches on an object while same body part continues in motion, tearing skin away from tissues below

healing: may be surgically reattached or may be removed and replaced by a skin graft; moderate scarring

Puncture

Causes: injury that is deeper than it is wide

Healing: surface may heal too fast, trapping infection inside; little scarring 

First Degree Burn

pain, redness and swelling; Tissue damage in the epidermis

Second Degree Burn

Pain, redness, swelling and blistering; Tissue damage in the epidermis and partially in the dermis; blood vessels and nerves are spared

Third Degree Burn 

White or blackened, charred skin that may be numb; Tissue damage is deep dermis to hypodermal layer; blood vessels and nerves are destroyed; skin grafting necessary to prevent infection, gangrene and, eventually, death