INTEGUMENTARY
SYSTEM
HONORS ANATOMY & PHYSIOLOGY
CHAPTER 5
HUMAN ANATOMY & PHYSIOLOGY
Integumentary System
 Includes:
 Skin
 Nails
 Hair
 Sweat & Oil Glands
FUNCTIONS
1. Protection:
chemical barriers: skin secretions:




acidic: hostile to most bacteria
some bactericidal
melanin: chemical pigment shield protects
DNA from damage by UV rays
physical barrier:



continuity of skin & hardness of keratinized cells
stratum corneum: multiple layers of dead cells
(brick) and water-resistantglycolipids (mortar)
Substances that Penetrate Skin
1.
2.
3.
4.
5.
6.
lipid-soluble substances: )2, CO2, Vit A,D,E,K
oleoresins: poison ivy, poison oak
organic solvents: acetone, dry-cleaning fluid, paint
thinner all dissolve cell lipids
heavy metal salts: Pb, Hg
selected drugs: nitroglycerine, nicotine, fentanyl,
seasickness meds, estrogen
penetration enhancers: help carry other drugs into
body thru skin
Functions – Protection cont’d
3. Biological Barriers:

dendritic cells of epidermis
 active
elements of immune system
 agn presenting cells

dermal macrophages
 phagocytes
 viruses or bacteria
 agn presenting cells

DNA
 e-
can absorb some UV rays  heat
Functions of Skin -2
 body temperature homeostasis
 when body overheated blood flow to skin increases &
some heat radiates off body, sweating (sensible
losses)
 when body cold less blood flows to skin, more to
trunk, goose bumps
 @normal temps sweat glands lose ~500 mL/dthru
insensible losses
Functions of Skin - 3
 Cutaneous Sensation (sensory receptors):
exteroceptors: sense stimuli from outside body
 Meissner’s corpuscles: in dermal papilla, feel light touch
 Pacinian corpuscles: deep dermis or hypodermis, feel
deep touch
 hair follicle receptors: feel breezes, insect
 free nerve endings: pain from irritants or extreme cold or
heat

Functions of Skin - 4
 Metabolic Functions:

1.
2.
3.
Sun light nrg powers some chemical reactions:
modified cholesterol Vit D precursor
keratinocyte enzymes
 “disarm” cancer-causing chemicals
 activate some steroid hormones (cortisone cream 
cortisol a more potent anti-inflammatory)
synthesize important proteins
 collagenase
Functions of Skin - 5
 Blood Reservoir
 dermal
vessels can hold up to 5%of blood vol.
 vessels constricted when
other
organs need extra blood
constriction shunts blood to areas in need
Functions of Skin- 6
 excretory function:


sweat contains urea, uric acid (breakdown
products of proteins)
NaCl + water lost with profuse sweating
Structure of the Skin
 made of 2 kinds of tissues
1. Epidermis
2. Dermis
Epidermis




made of stratified squamous epithelium
some keratinized, some not
avascular
Cells:
 Keratinocytes
 majority of cells
 make keratin
 Melanocytes
 Langerhans Cells
 Immune System
 aka dendritic cells
Cells of the Epidermis
Epidermal Layers
1. stratum basale

deepest layer

constantly undergoing cell division/ cells pushed
upward
2. stratum spinosum
3. stratum granulosum
4. stratum lucidum (only in thick skin)

clear, flatter, more keratin
5. stratum corneum (cornified = keratinized)

outermost layer/ 20-30 dead cells thick
Layers of Epidermis
Thick Skin
 areas subject to abrasion
 palms
 soles
 finger
tips
Thin Skin
 covers rest of body
 thinnest skin (thinner subcutaneous layer)
 eyelid:
0.02mm
 bridge of nose
 ankles
 knuckles
Melanin
 pigment
 (yellow to brown to black)
 produced by melanocytes
 most are in stratum basale
 cells stimulated to make more melanin when
skin exposed to sunlight
shields DNA from damaging effects of UV radiation
freckles & moles: seen where melanin concentrated in 1
spot

Freckle
Dermis
 a strong, stretchy envelope that helps to
hold the body together

leather is the dermis of whatever animal it was made
from
 made of dense CT: strong& flexible
 rich blood supply
 2 regions:
1. Papillary
2. Reticular
Papillary Layer
 upper dermis
 dermal papillae: uneven projections into
lower epidermis that contain:
1. capillaries
2. pain receptors
3. touch receptors: Meissner’sCorpuscles
4. in thick skin: form ridges (fingerprints)
that improve gripping ability

genetically determined
Dermal Papillae
Dermis: Reticular Layer
 deepest skin layer
 Contains:
1. sweat & oil glands, hair follicles, blood
vessels
2. Pacinian corpuscles (deep touch receptors)
3. many phagocytes
4. fibers: elastic: give young skin elasticity
collagen: make dermis tough & keeps
skin hydrated by binding to water
Dermis
Striae
 extreme stretching of skin  white scars
 aka stretch marks
Blisters
 fluid –filled pocket separating epidermis/dermis
Skin Color
 3 pigments contribute to skin color:
1. Melanin

amount & kind (yellow  black)
2. Carotene

orange – yellow pigment

stratum corneum & subcutaneous layers
3. Hemoglobin

amount O2 bound to it in RBCs in dermal blood
vessels

has greater affect in light skinned people
Skin Color in Sickness & in Health
 cyanosis: blue hue to skin; due to poorly




oxygenated blood
erythema: redness, due to increased blood
flow (infection, inflammation); burn, HT,
blushing
pallor: paleness, due to emotions, anemia,
low BP, decreased blood flow
jaundice: yellow; usually from liver disease
(not clearing bilirubin)
hematomas: bruising (bleeding under skin)
Appendages of the Skin
 derivatives of epidermis:
 hair&
hair follicles
 nails
 sweat
glands
 sebaceous glands
Hair & Hair Follicles
 areas of skin with no hair:
 palms
 soles
 lips
 nipples
 parts
of external genitalia
Functions of Hair
 sense insects b/4 they bite
 protects against heat loss (scalp)
 protects against sun
 shield eyes
 filter air inhaled through nose
Hair
 “pili”
 produced by hair follicles
 consist of dead keratinized cells
 keratin here compared to keratin in epidermis:
 tougher
& more durable
 individual cells do not flake off
Hair
 3 concentric layers of keratinized cells
1. Medulla

innermost

large cells & air space

absent in fine hair
2. Cortex

surrounds medulla

layers of flattened cells
3. Cuticle

1 layer overlapping cells

provides strength
Hair Pigment
 melanocytes @ base of follicle  to cortical cells
 differing proportions of melanins of different
colors give different hair colors
 melanin production decreases (delayed-action
genes)  replaced by air bubbles  gray  white
Hair Follicle
 fold down from
epidermis  dermis
forming hair bulb
 sensory nerve ending :
root hair plexus
surrounds hair bulb
 bending hair stimulates
plexus
 sensitive touch
receptors
Hair Follicle
 dermal papilla: bit of
dermal tissue protruding
into base of follicle

capillaries
 matrix: actively dividing
cells produces hair
 arrector pili: smooth
muscle from dermal part
of follicle  epidermis @
angle
 contraction  goose
bumps
Types of Hair
VELLUS
TERMINAL
 pale, fine hair
 coarse long hairs
 children and females
 eyebrows, scalp
 @ puberty:
Factors the Influence Hair Growth
Nutrition

poor nutrition  poor
growth
2. Hormones
3. local inflammation 
increased growth
1.
 normal growth~2.5
mm/wk
 fastest growth teens  40’s
then slows
 each follicle goes thru
cycle:
1. active growth phase
 wks  yrs
2. regressive phase

3.
matrix cells die
resting phase
 1 – 3 mos
Hirsutism
 excessive hairiness
 could be from ovarian or
adrenal gland tumor
secreting high levels of
androgens
Alopecia
 hair thinning
 starts @ anterior hairline
 posteriorly
 males:


by age 35: 40%
by age 60: 85%
Male Pattern Baldness
 most common type of
baldness
 X-linked recessive
inheritance:
 delayed-action gene
switches on in adult &
changes hair follicle
response to
testosterone  follicles
very short growth cycle
 may get vellus hair
Alopecia Areata
 immune system attacks hair follicles
 hair falls out in patches
Nails
 scalelike modification of epidermis

forming clear protective covering on dorsal surface of
distal digits
 hard keratin
 Functions:
1. pick up small objects
2. scratch
3. protect tips of digits
Parts of a Nail
1. free edge
2. nail plate or body
3. nail bed
proximal portion = matrix:
nail growth
4. proximal root
5. nail folds:
 proximally :eponychium
(cuticle)

Nail Abnormalities
 yellow: thyroid or
respiratory problem
 thickened yellow:
fungus infection
 outward concavity: iron
deficiency (spoon nail)
 horizontal lines:
malnutrition
Sweat Glands
 aka sudoriferous glands
 over entire skin surface
except:
 nipples
 parts of external
genitalia
 2 types:
1. Eccrine Sweat Glands
2. Apocrine Sweat
Glands
 secretory cells
surrounded by
myoepithelial cells:
contract when stimulated
by nervous system 
sweat goes thru duct to
skin
Eccrine Sweat Glands
 more numerous than
apocrine
 abundant on palms &
soles of feet
 secretory cells in dermis
 sweat released thru
pore (not skin pore)
Eccrine Sweat Gland
 secretion: hypotonic
(99% water) filtrate of
blood
 also has:
 salts
 vitamin C
 abys
 wastes: urea, uric acid,
NH3
Eccrine Sweat Gland
 regulated by sympathetic division of ANS
 Functions:
1. prevent overheating

forehead  spreads inferiorly
2. “emotional” sweating


fright or extreme nervousness
palms, soles, or axilla  over body
Apocrine SweatGlands
 axillary & anogenital areas only
 larger than eccrine glands
 found deeper in dermis/hypoderrmis
 empty onto hair follicle
 odorless until released onto skinwhere bacteria
decompose molecules  musky, unpleasant odor
 in addition to what is found in eccrine sweat:
fatty acids
 proteins

Apocrine Sweat Glands
 begin functioning @ puberty
 activated by sympathetic division of ANS during:
pain
 stress

 exact function uncertain but likely analogous to
animals glands that secrete pheromones
Ceruminous Glands
 modified apocrine glands
 secretion mixes with
sebum (made by
sebaceous gland) 
cerumen (ear wax)
 Function:
 deters insects
 blocks entry of foreign
objects
Mammary Glands
 specialized sweat glands that secrete milk
Sebaceous Glands
 oil glands
 found with hair follicles
 smaller on trunk & limbs
 large on face, neck, upper chest
 secrete sebum: oily substance
 develop as outgrowths of hair follicle
 arrector pili contractions force sebum to skin
surface
 androgens stimulate secretion (activity starts in
puberty)
Sebum
 Functions:
1. softens & lubricates skin & hair
2. bactericidal action
Whitehead
 created by:

sebum blocks
sebaceous gland duct
Blackhead
 sebum in whitehead
oxidizes
Acne
 active inflammation of
sebaceous glands
 see: pustules or cysts on
skin surface
 associated with bacterial
infection (staph)
Skin Cancer
 Benign tumors such as warts and moles are not
serious.
 Malignant tumors can start on the skin and invade
other body areas.
 Crucial risk factor- overexposure to UV radiation
Skin Cancer
 20% in USA will develop skin cancer (↑ing #s)
 #1 risk factor: Sun UV radiation
DNA damaged
 suppresses tumor suppressor gene
 new skin lotions contain liposomes  initiate repairof
damaged DNA

Types of Skin Cancer
 Basal cell carcinoma- most common, 30% of all
white skin people get it.
Arises from the stratum basale layer of the skin
 99% curable if caught early
 Dome shaped nodules that form an ulcer in the center.

 Squamous Cell carcinoma Arise from stratum spinosum
 Grows rapidly and metastasizes if not removed
 Small red rounded elevation on the skin
Basal Cell Carcinoma
Lesion removed from patient
Basal Cell Carcinoma
Squamous cell carcinoma
Skin Cancer Types cont.
 Melanoma
 Cancer of melanocytes (very dangerous)
 5% of skin cancers but rising fast
 Can arise from preexisting moles
 Appears as a spreading brown or black patch
 Chance of survival is poor if the lesion is greater than 4 mm
thick
Melanoma
What is the ABCD rule?
 Used for recognizing melanoma
 A-Asymmetry: two sides of the pigmented mole do
not match
 B-Border irregularity: borders are not smooth
 C- Color: lesion has a multiple of colors
 D- Diameter the spot is larger than 6 mm in
diameter (size of a pencil eraser)
What are the 3 types of burns?
 First-degree burns: only the epidermis is
damaged. Redness, swelling and pain are common.
(sunburn) 2-3 days to heal
 Second-degree burns: epidermis and upper layers
of dermis. Blistering can occur. 3-4 weeks to heal.
 Third-degree burns: involves the entire thickness
of the skin. (pg. 164-165)
Second-degree burns
Third-degree burn
Burn Evaluation
 Rule of 9’s:
 divides body into11areas each 9% of body surface
area + 1% for genitalia
Burn Treatment
 patients require extra calories to replace lost
proteins & allow tissue repair

must add parenteral nutrition (IV)
 2◦ infections main threat
24 hrs after burn wound is sterile
 fungi, bacteria,& other pathogens multiply rapidly
 Immune system deficient
 infection leading cause of death in burn victims

Burn Treatment: Skin Grafts
 1st debride burned tissue
 wash area with antibiotic in solution
 apply synthetic membrane temporarily
 skin graft: healthy skin applied to area
autograft: taken from the patient
 synthetic skin: silicone “epidermis” bound to spongy
“dermis” made of collagen fibers & ground cartilage 
patients own cells absorb &replace synthetic
* no rejection from immune system

Think About It