Integumentary System: Functions
PROTECTION from:
Mechanical damage Chemical damage Bacterial damage – antibacterial
secretionsUV radiation – melanin pigment protectsThermal damage – cold/pain receptorsDessication – keratin waterproofing
Even more functions…Helps with heat loss or heat retention – sweat glands and capillaries
Helps excrete urea – perspiration
Makes Vitamin D – sunlight
converts cholesterol molecules in our skin
2 Types of Skin Tissue
EpidermisKeratinocytes that can make the protein keratin (become hard & tough)
DermisConnective tissue that contains glands, capillaries and nerves
Stratum Basale
These are the “stem cells” of skin
As they mature, they climb the layers of epidermis
Melanocytes are here and make melanin (keratinocytes gobble up the melanin)
Stratum Corneum
20 to 30 layers of dead skin cells filled with keratin
Waterproofing material
This layer is thicker on palms and soles
“Beauty is only skin deep”?!
Harlequin Ichthyosis
Autosomal recessive
Generate in 1 day the amount of skin a normal person would generate in 14 days
Constant care, moisturizing, bathing to remove keratin layer
Oldest living person is 24
Blind from corneal abrasions
Tattoo RemovalDermabrasion
Salabrasion (rub with salt)
Cryosurgery
Excision
Latest: Q-switched lasers
Different lasers for different color pigments
Black, purple, red easiest
Yellow, green hardest
Burns: 1st Degree
1st degree: only epidermis is damaged
Heal in 2 to 3 days without a problem
Sunburn without blistering
Burns: 2nd Degree
Injury to the epidermis and part of the dermis
Characterized by pain, redness, swelling, and blisters
Still enough epithelial cells to regenerate
“Partial-thickness” burn
Burns: 3rd Degree
Worst
Entire epidermis and dermis is destroyed
No more stem cells, no blood supply
No nerve endings (no pain, but only at first)
Must skin graft
PsoriasisSilvery, scaly patches of skin overgrowth
Prevalence 2 – 3 %
Onset: 15-25 years of age
Thought to be autoimmune
3 Main Types of Skin Cancer
Basal cell carcinoma:
most common
least malignant
sun-exposed areas
99% cure rate with excision
3 Main Types of Skin Cancer
Squamous cell carcinoma:
Shallow ulcer that won’t heal
Sun-exposed areas
Can grow rapidly
Metastasizes (travels to lymph nodes and other parts of the body)
3 Main Types of Skin Cancer
Malignant melanoma:
Only about 5% of all skin cancers, but incidence is on the rise
Arises from accumulated damage to DNA in a melanocyte
Chance for survival: 50%
ABCD rule
ABCD Rule of Malignant Melanomas
Asymmetry: 2 sides of the pigmented spot do not matchBorder irregularity: borders are not smooth but exhibit indentationsColor: pigmented spot contains areas of different colors (black, brown, tan, red)Diameter: spot is larger than 6 mm in diameter (size of pencil eraser)
Sebaceous Glands
Everywhere except palms and soles
Usually empty into hair follicle
Makes “sebum”Keeps skin soft/moist
Antibacterial
Increased production during puberty
When gland is blocked: whiteheads/blackheads
Sweat Glands: 2 Types
Eccrine glands: make “sweat”Clear secretion of water, salts, urea, lactic acid
Acidic, inhibits bacteria
Apocrine glands: axilla (armpit) and genital area
Contain sweat plus proteins/fats (not antibacterial)
Hair Follicles
Hair follicle: makes the hair
Hair root: alive
Hair shaft: dead material; almost all protein
Arrector pili: tiniest muscles; goose bumps