Chapter 4 Integumentary System. Basic Skin Functions.
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Transcript of Chapter 4 Integumentary System. Basic Skin Functions.
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