Chapter 4Integumentary System

Basic Skin Functions

1. Keeps water and other molecules in

2. Keeps water and other molecules out

* Keratin – water-proofing protein

3. Insulates

4. Cushions deeper organs

5. Protects from:

a. Mechanical damage – cuts/bumps

b. Chemical – acids and bases

c. Thermal

d. UV

e. Bacteria

6. Regulates heat loss with a capillary network and sweat glands

7. Mini excretory system (urea, salts, water)

8. Manufactures proteins and vitamin D

9. Sensory receptors

Structure of the Skin

Two Layersa. Epidermis

b. Dermis

• Deep to the dermis is the Hypodermis or subcutaneous layer

• This Layer is deep to the dermis but is not part of the skin - anchors

A. Epidermis

• 5 layers• Avascular – no blood• Cells are made in the bottom layer and

move up• New epidermis – 25 to 45 days

Melanin

• Skin pigment• Yellow to brown/black• Produced by melanocytes in the

bottom layer• Tanning occurs when melanocytes

produce more pigment• Melanin pigment umbrella over nuclei• Freckle – local concentration of

melanin

B. Dermis

• Strong stretchy envelope that holds the body together

• Two layers• Fingerprints originate from projections

in this layer

• Deepest layer – blood vessels (temperature), sweat, oil glands

• Has collagen – toughness of the dermis

• Elastic fibers – elasticity of the skin

- wrinkles when lost

Skin Color

• Is caused by three pigments

1. amount and kind of melanin

2. Amount of carotene – orange

3. Amount of oxygen in hemoglobin

(when there is a lot of oxygen – red)

(when there is little oxygen – blue)

Affected by emotional stimuli and disease

1. Erythema – redness

2. Pallor – pale

3. Jaundice – yellow – liver

4. Bruises – blood vessels damaged and blood leaks out

5. Cyanosis – blue cast to skin

- not enough oxygen

Appendages of the Skin

I. Cutaneous glands (Exocrine) – give off

a. Sebaceous (oil) glands

1. empty on to a hair follicle

2. produce sebum – lubricant – kills

bacteria

3. Duct blocked - zit

b. Sweat glands

1. sweat – clear secretion that is

primarily water plus NaCl, vitamin C,

traces of metabolic waste (urea)

2. Important for heat regulation

3. Hot days – lose up to 7L

II. Hair and Hair Follicles – produce hair

a. Protective functions

b. Root – part in the follicle

c. Shaft – part growing out of the skin

d. Made of dead cells full of keratin

III. Nails

a. Scalelike, modification of the epidermis

b. Free edge, body, root

c. Made of dead cells full of keratin

Homeostatic Imbalances of the Skin

There are 1000’s

1. Infections and Allergies

Athlete’s Foot

• Itchy red peeling condition between the toes

• Caused by: Fungus

Athlete’s Foot

Boils

• Inflammation of the hair follicles and sebaceous glands

• Staphylococcus aureus• Caused by: inflammation of a follicle

Boils

Carbuncles

• Composite boils• Caused by: bacteria infection

Carbuncles

Carbuncles

Cold Sore

• Small fluid filled blisters that itch and sting

• Caused by: Herpes simplex infection• Virus in cutaneous nerve• Dormant until emotional upset, fever,

or UV light

Cold Sore

Contact Dermatitis - Poison Ivy

• Itchy redness, swelling and blistering• Caused by: Exposure to chemicals

Poison Ivy

Impetigo

• Pink water filled lesions• Around mouth and nose• Yellow crust and rupture• Caused by: Highly contagious staph

infection• Common in elementary kids

Impetigo

Psoriasis

• Chronic condition• Reddened epidermal lesions• Dry silvery scales• Can be disfiguring• Caused by: cause is unknown –

hereditary?• Attack often triggered by trauma,

infection hormonal changes, stress

Psoriasis

Acne

• Caused by: blockage in the hair follicle

2. Burns

• Skin is as thick as a paper towel• Damage affects all other body systems• Burn – tissue damage and cell death

caused by heat, UV radiation, chemicals

Two Life Threatening Problems

1. Body loses precious supply of fluids

2. Infection

Rule of the Nines

• Estimates fluid loss• 11 areas of the body, 9% each, 1% area

around the genitals

Burn Classification

First Degree

• Epidermis only• Red/swollen• Re-growth – cells still ok• Partial thickness burn

Second Degree

• Epidermis and top of dermis• Blisters• Re-growth – cells still ok• Partial thickness burns

Third Degree

• Full thickness burn• Area blanched or blackened• Nerves destroyed• No re-growth - graft

Burns are Critical if:

• More than 25% of the body has second degree

• 10% had third degree• Third degree on face, hands or feet

Skin Cancer

Basal Skin Carcinoma

Squamous Cell Carcinoma

Melanoma

The End