Integumentary System
Chapter 5
p. 116-132
Skin Coloring
„ Normal skin coloring is due to 3
pigments:
„
„
1) Hemoglobin: gives pinkish
hue due to red blood cells
2) Melanin: melanocytes give
variety of brown, tan, & black
„
„
Amount determined by heredity
& UV exposure
3) Carotene: yellowish pigment
from egg yolks & orange
vegetables
Skin Markings
„ Hemangiomas: “birthmarks;”
patches of colored skin caused
by benign tumors of skin
capillaries
„ Freckles & Moles: clusters of
melanocytes; vary w/ heredity &
UV exposure
„ Friction Ridges: “fingerprints;”
unique to EVERY person
„ Flexion Creases & Lines:
lines on palms formed after
birth
Skin Functions
„ 1) Barrier
„ Keratin: provides toughness & resists
scratches
„ Acid Mantle: sweat makes skin acidic to repel
bacteria
„ H2O barrier: keeps valuable H2O from being
lost
„ UV barrier: keeps UV from penetrating deep
into body
„ 2) Vit D Synthesis: UV rays needed to make
vit D in the skin
Skin Functions (con’t)
„ 3) Cutaneous Absorption:
small amts O2, CO2, & some
chemicals & vitamins can be
absorbed through skin
„ 4) Sensory Functions: senses
touch & temp.
„
Sensitivity varies around body
„ 5) Thermoregulation:
„ A) Vasodilation &
Vasocontriction
„ Body can control amt blood
in skin to prevent or increase
cooling of blood
„ B) Sweating: evaporation
cools the skin
ACCESSORY STRUCTURES
„ 1. HAIR
„ 2. NAILS
„ 3. HAIR FOLLICLES
„ 4. SEBACEOUS GLANDS
„ 5. SWEAT GLANDS
Hair Types
„ Key difference in hair, skin, & nails is amt
hard keratin
„ ALL people have same # hair follicles
„
Differences due to texture & amt pigmentation
„ Types:
„
„
„
Languno: fine, downy hair in unborn fetus
Vellus: fine, downy hair in children
Terminal: course, darker hair on head & body
after puberty
Hair Structure
„ Bulb: consists of root &
shaft (above skin)
„
„
„
Medulla: airy core
Cortex: ↑ keratinized cells
Cuticle: outer scaly cells
„ Receptors: sense hair
movement
„ Arrector Pili muscles:
make hair stand up when
cold or scared
Hair Texture & Color
„ Texture due to cross-sectional appearance
„ Straight: appears round
„ Wavy: appears oval
„ Curly: appears flat
„ Color due to pigments
„ Brown/Black: ↑ amt melanin
„ Blond: ↓ amt melanin
„ Red: tricosiderin pigment
„ White: air in medulla & no pigments
„ Gray: mix of white & pigmented
Hair Growth
„ Growth due to mitosis in stratum basale of
epithelial root sheath (outer layer)
„ Grows avg of 1mm/3days; Lose 10-100
strands daily
„ Growth Abnormalities:
„
„
„
Alopecia: thinning or loss of hair due to
stress, fever, or disease
Pattern Baldness: loss occurs only in certain
areas due to heredity (X-linked trait)
Hirsutism: excessive hairiness in women &
children due to hormones
Nails
„ Derived from stratum corneum
„ Contain ↑ amts hard keratin
„ Structure:
„
„
Nail Matrix: growth zone underneath skin
Nail Plate: visible area
„ Grow approx. 1mm/week
„ Nail Abnormalities:
„
„
Iron deficiency: cause flat or concave nails
Hypoxemia (↓ O2): cause “clubbed” nails
Skin Glands
„ 1) Sweat Glands
„
„
Merocrine Glands: produce sweat throughout
body
Apocrine Glands: in pubic area; give off
scent after puberty
„ 2) Sebaceous Glands: produce sebum (oil)
in hair follicle
„ 3) Ceruminous Glands: produce cerumen
(ear wax) in ear canal
„ 4) Mammary Glands: produce milk in
females when pregnant
Skin Diseases (see Table 7.4)
„ 1) Acne: follicle plugged
w/ bacteria
„ 2) Eczema: itchy red
lesions caused by
allergies
„ 3) Ring Worm: fungal
infection of warm, moist
area (“athletes foot”)
„ 4) Warts: benign tumors
caused by HPV virus;
spread thru touch
Skin Cancer
„ ALL caused by UV radiation
„ 1) Basal Cell Carcinoma: most
common form; easily treatable
„ 2) Squamous Cell Carcinoma:
cancer of keratinocytes
„ 3) Malignant Melanoma: found
in moles; most deadly and fastspreading (metastisized)
Skin Burns
„ May cause death due to fluid loss, infection, &
toxic chemicals from dead tissue
„ Degrees:
„
„
„
1st: little redness & pain (most sunburns)
2nd: damage to epidermis & dermis (blistering)
3rd: complete destruction of skin (requires
grafting)
„ Treatment:
„ fluid replacement, infection control, skin
replacement (grafting)