Integumentary SystemA.K.A.: SkinChapter 6

Integumentary Overall Functions

1. Protect Underlying tissues & organs

2. Excrete salts, water, & organic wastes (excretory organ)

3. Maintain normal body temperature

4. Synthesize vitamin D in epidermis

5. Sensation of touch, pressure, pain, & temp.

Integumentary Overview Main Structure:

1. Cutaneous Membrane

1. Epidermis

2. Dermis

2. Subcutaneous layer

Accessory StructuresHair FolliclesExocrine Glands

SebaceousSweat

NailsNerve Endings

Skin

Epidermal Layers:Stratified Squamous1. Stratum Germinativum – Stratum Basale

Mitosis2. Stratum Spinosum

Some cells still divide3. Stratum Granulosum

Keratin (protein): Water resistant, durable (poor envmt for

bacteria) also nails, hooves, horns, quills No more mitosis

4. Stratum Lucidum: palms & soles only5. Stratum Corneum (superficial)

Flattened, dead, keratinized cells

Day 1

Day 14

Shed after 2 wks

Epidermal Layers

Eyelid Palm & Sole

1. Vitamin D synthesis Stratum spinosum & germinativum

UV light + steroid precursor Vitamin D Vitamin D Purpose:

Needed for bones to absorb calcium Ricketts: bone disease

Epidemic in inner city

2. Protection/ Waterproof

3. Protective Senses

Epidermal Functions

Skin Color: 2 Determinants1. Hemoglobin: Good O2 reddish tint

• More red, inflamed• Less pale• Cyanosis: sustained decr. O2 blue

• Caused by extreme cold or cardiopulm. dz.

2. Skin Pigments1. Carotene: (carrots)2. Melanin:

• Melanocytes (germinativum & dermis), Melanocyte stimulating hormone (MSH)- pituitary gland & Melatonin- pineal gland• Albino: can’t produce melanin

Cyanotic Foot

Melanocytes

Nerve Endings of Epidermis1. Free Nerve Endings:

Pain & Temp. (epidermis & dermis)

2. Merkel’s discs: static L.T. (epidermis)

3. Meissner’s Corpuscles: dynamic L.T. (dermis)

4. Pacinian Corpuscles: deep pressure & vibration (deeper tissue- subcutaneous)

Dermis: 2 layers1. Papillary Layer

Areolar connective tissue Rich in capillaries & nerves Dermal papillae: extensions

into epidermis Epidermal ridge (fingerprints)

2. Reticular Layer Dense irregular connective

tissue Support, attachment, & allows

flexibility

Other Dermal Components & Functions

Accessory Organs: hair, sweat & sebaceous glands

Blood vessels Lymphatics: assists in tissue repair Nerve fibers:

Sensory receptors & nerve fibersControls blood flow & gland secretion rates

Dermis: Wrinkles & Stretch Marks

UV radiation & over stretched skin (pregnancy)Stretch elastin beyond limitsWrinkles & stretch marks

Retin-A: vitamin A derivativeAcne treatment

incr. blood flow to incr. dermal repair & decr. wrinkles

Subcutaneous Layer: Hypodermis

Structure: loose connective tissue w/ abundant adipocytes In babies: more adipose WHY??Adults: fat located differently in male, female

Function: stabilizes skin, store energy, insulateVery elasticGood for med injection

Slow, steady infusion No vital organs & limited # capillaries

Accessory Structure: Hair Follicles Hairs found everywhere except palms, soles,

lips, sides of fingers & toes Hair Structure:

1. Shaft: size, shape, and color of hair 2. Root: encloses matrix3. Hair Follicle:

Papilla: areolar tissue w/ capillaries Matrix:

Medulla- division (inner layer) Cortex- begin keratinizing Cuticle- fully keratinized (outer layer)

4. Arrector pili muscle: smooth muscles5. Nerve Root Plexus

Hair Follicle

Hair Types & ColorsTypes:1. Vellus: fine, “peach fuzz” (most of body)

2. Terminal: heavy, colored (head, eyebrows)

3. Intermediate: in-between (legs & arms)

Colors:1. Determined by melanocytes at papilla

2. Genetic

3. Pigment production slows w/ age graying

Exocrine: Sebaceous Glands1. Sebaceous glands

Holocrine glands Associated with hair follicle: secrete sebum Sebum: prevents drying & inhibits bacterial growth Shampoo: removes natural oilstiff, dry hair

2. Sebaceous Follicle Secretes directly to epidermis

face, back, chest Acne: (caused by hormone changes)

Glands blocked, secretions accumulate inflammation bacterial infection

3. Ceruminous Gland: cerumen (earwax)to protect inner ear

Sebaceous Follicle & Gland

Exocrine: Sweat Glands- 2 Types

MerocrineApocrine

1. Apocrine Sweat Glands Secrete through hair Armpits & groin 1st secrete at puberty hormones Sexual state & identity + envmt for bacteria odor

2. Merocrine Sweat Glands Widespread (palms/ soles) Secrete to skin surface Function:

Cooling effect Protection: dilute chem, wash

away bacteria

Skin Local Control : Inflammation Epidermis= great protection

Thick, keratinized cellsTight junctions b/w cellsSebaceous & sweat glandsAvascular

Papillary layer= bacterial heavenOnce bacteria enters papillary

layer inflamm response Mast cells initiate response

Skin Local Control: Regeneration1. Clot Formation:

1. Platelets & fibrin (scab) Isolates area Creates network for new

cell migration

2. Division, Migration, & Phagocytosis:

1. Stratum germinativum Divide & Migrate Granulation tissue: fibrin

clot, fibroblasts, capillary network

2. Macrophages Phagocytosis

Regeneration (con’t)3. Scar tissue (lots of

collagen, little blood)1. Fibroblasts

Damaged hair follicles, sweat & sebaceous glands replaced w/ scar tissue

4. Contraction: 1. Platelets & epithelial cells

Pull wound together

5. Clot dissolves

Aging Integumentary System

Temperature Control

1. Sweat Glands Cooling effect

2. Muscles Mostly skeletal & arrector pili

3. Blood Flow Superficial: heat transfer Deeper: maintain heat

Application: Skin Cancer Basal cell carcinoma: Most common

Malignant Germinativum (basale) layer Common Cause: UV radiation Metastasis rare

Squamous Cell Carcinoma: 2nd most common Malignant Common cause: UV radiation Metastasis rare

Melanoma: most dangerous & rare Malignant Cancerous melanocytes Common cause: UV radiation High Metastasis rate

Diagnosis: ABCD Assymetry, Border, Color, Diameter

Application: Burns & Skin Grafts Depth of Burn1. First degree

Superficial epidermis Erythema, sunburn red, blisters, painful Heals in few days

2. Second degree Down to germinativum & dermis red, moist,

blisters, blanch with pressure Painful Accessory structures unaffected Minor if >15% body burned 3 weeks to heal

3. Third degree Down to subcutaneous white, brown, black, or

whit, dry Less painful WHY? Hard to heal if extensive through body skin graft

may be needed

PartialThickness

FullThickness

Burns& TreatmentsEstimation of Burns•Rule of 9’s (p. 204)

Skin Grafts Split- Thickness

Epidermis Full-Thickness

Epidermis & Dermis

Skin FlapAll 3 layers

Other Concerns:

1. Fluid & electrolyte balance

2. Thermoregulation

3. Infection

4. Contractures

Rule of 9’s

Application: Decubitus Ulcer Decubitus Ulcer= Pressure Sore

Most common: over bony areas (i.e. sacrum, heel) Cut off blood supply decrease nutrients & O2 to tissues Population most affected:

Bed ridden Decreased sensation: diabetics (feet & hands), SCI Wheelchair bound

Stages: I: reddening II: blister III: all 3 skin layers affected IV: all 3 layers of skin & underlying tissues (muscle/

tendons/ bones) Prevention: positioning every 2 hours, weight shifts in

wheelchair, cushioning/ supports

Risk ofInfection

Decubitus Ulcers