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Ch. 4
Integumentary System:
The Skin and Its Parts
Applied Learning Outcomes
1. Use terminology associated with
the Integumentary system
2. Learn about skin structure,
function, appendages, glands, and
care
3. Understand the aging and
pathology of the Integumentary
system
Case Study Investigation – Ch. 4
You are observing an elderly woman who is seeing
a personal trainer as part of her rehabilitation
therapy. The woman was hospitalized for
problems associated with obesity &
high blood sugar. She is now going
through an exercise program to helpb
bring her back to health. While
working out, one of her socks rolled
down exposing the lower part of her
leg. A glance at the side of her left
leg, revealed a large, shiny, deep red
sore. The sore had a dark margin, like tanned skin.
Parts of it looked as if you could see right through
to the muscle. The woman saw your face reacting
to the sore and kindly said, “Don’t worry about
that, it doesn’t cause me any pain.”
Part of the personal’s trainer’s
responsibility is to pay attention to
the pathology that can be worsened
by the patient’s rehab. By the end
of this chapter you will be asked to
determine the possible problems
causing this skin condition.
Human Skin Trivia
 skin – largest organ in body (25sq.ft or 16%
of your body weight)
 lose an avg. of 4 - 100 hairs/day
 stretchable & washable
 avg. scalp has 100,000 hairs
 shed 40lbs of skin/lifetime on avg. (1 layer
every 24 hrs)
 body loses 30,000–40,000 dead cells/min.
 45 miles of nerves in skin
 blondes have more hair than brunettes
Did You Know?
Chaetophobia is
the fear of hair.
Tonsurphobia is
the fear of
haircuts.
6
Did You Know?
Hair generally
grows at a rate
of approximately
3/16” per day, or
approximately
½” per month.
7
Did You Know?
Hair is naturally
colored by pigment
granules (melanin)
in the cortex
whereas dyed hair
has melanin in the
cuticle as well as
the cortex.
8
Overview
The skin is the largest organ is in
the body and is composed of:
Blood vessels
Nerve
Hair
Nails
Skin
Glands
Receptors
Overview
Inherent: qualities an organism is born with
ex. Genes for making nails only turn on in
the upper tips of the fingers and toes
Adaptive: ability of an organism’s genes to
respond to environmental changes
ex. calluses, suntan, skin stretches as the body
grows and shrinks back after a woman gives
birth
Functions of Integumentary System
• Protection - against environment (UV rays, microbes);
and self-repairs cuts & burns
• Heat regulation – maintain homeostasis (blood vessels)
• Water resistant – prevents water from flushing out
important nutrients
• Sensation – receiving stimuli from the environment
(receptors)
• Absorption - can receive O2, N2, medicine
• Waste excretion – can excrete CO2, urea, sweat
• Synthesis of Vitamin D – Vit. D helps maintain
normal blood calcium & phosphorus
3 Major Layers of the Skin
1.
a.
b.
2.
a.
b.
Epidermis
stratified squamous tissue (epithelial)
strong & waterproof (keratin)
Dermis
dense connective tissue
contains blood, sweat
& oil glands
3. Hypodermis (subcutaneous)
a. adipose tissue
b. anchors skin (E & D)
to underlying organs
Microscopic View
Epidermis
- get a new one every
25-45 days
- melanocytes (melanin cells)
- keratocytes (keratin cells)
Dermis
- functional layer
Hypodermis / Subcutaneous
- adipose tissue
5 Layers of the Epidermis
OUTSIDE THE BODY*****
1. Stratum corneum
(dead cells & melanin
which gives skin color)
2-4. middle layers
(protein keratin
provides strength)
5. stratum
germinativum
(living & dividing cells)
DERMIS*****
Why don’t we bleed when we shave??
• The epidermis is AVASCULAR, meaning
it has no blood supply of its own.
• You only bleed if you cut deep enough to
reach the dermis.
Dermis
 functional layer
 contains blood vessels, sweat & oil
glands, hair follicles, muscle fibers, nerve
endings & elastic fibers
 dermal papillae  finger-like
projections of the dermis that
1. bind epidermis & dermis
2. form ridges & grooves that create
fingerprints
Dermal
papillae
Hypodermis (subcutaneous)
 composed of adipose tissue & elastic
(connective) fibers
 anchor skin to underlying fascia (tissue
that covers muscles, skull & some organs)
 major blood vessels & nerves branch
upward into the dermis
 absent/thin in eyelids, penis, scrotum, &
nipples; responsible for increase in breasts &
hips in females
Subcutaneous Injection
 ideal site for rapid & relatively
pain free absorption of injected material
(i.e. insulin/
flu shot)
using a
hypodermic
needle
Concept Check Questions 1-3
1. List 5 major components of the Integumentary
system?
blood vessels, receptors, glands, nails, nerves, & hair
2. Distinguish between inherent and adaptive
characteristics. Give an example of each.
Adaptive – cause changes in skin that adjust the structure
of skin to environmental conditions (tanning)
Inherent – structures that appear at birth (nails)
3. List 5 main functions of the Integumentary
system? protection (melanin), heat regulation (adipose tissue, blood
vessels, sweat), absorption (blood vessels, pores), water-resistant
(keratin,oil), sensation (receptors), waste excretion (pores, sweat),
makes Vit. D (melanin)
Concept Check Questions 4-6
4. What are the 3 layers of skin from superficial to
deep?
epidermis, dermis, hypodermis/subcutaneous
5. What kind of tissues can be found within each
layer of skin?
epidermis  stratified squamous (epithelial)
dermis  connective tissue
hypodermis  adipose & connective tissue
6. How do the 5 layers of the epidermis differ? Be
specific.
stratum corneum  dead cells and melanin for color
middle layers  keratin for strength
stratum germinativum  living and dividing cells
Concept Check Questions 7-9
7. Why don’t we bleed when we shave usually?
When would you see blood?
The epidermis is avascular – doesn’t contain any blood
vessels; only bleed if you reach dermis
8. Why is the dermis considered the “functional”
layer?
contains blood vessels, receptors, glands, muscle, nerve
endings
9. Where are dermal papillae found AND what 2
functions are they responsible for?
Found in dermis; 1) connects the dermis to the epidermis
2) create fingerprints
Skin Appendages
 assist skin
with its
functions
glands
nerves
nails
hair
http://www.youtube.com/watch?v=I
At_MfIJ-Y
Blood Vessels
 expand/contract according to internal body
temperature of body
1. warm body blood flow increases heat leaves
2. cold body
blood flow decreases
heat stays
3. sweat evaporation
 lowers body
temperature
Glands
 3 types of glands commonly found in skin
1.
Cerumenous glands (wax)
2.
Sebaceous glands (oil)
3. sweat
a. apocrine sweat glands
b. eccrine sweat glands
Ceruminous Glands
 produce cerumen or ear wax that line
ear canal
 surrounded
by small hairs
 collects dirt
& dust and
carries it out
of the ear
Sebaceous Glands
 attached to hair follicle
 produces sebum, an oily secretion
 sebum lubricates hair and surface of skin to
prevent them
from drying
out
Sweat Glands
 produces
sweat through pores
 2 types
a) Apocrine:
 made of protein, fat,
etc.
 responsible for body
odor
 found in armpits,
naval, groin &
areolae (secrete fat
Into milk ducts)
Apocrine Sweat Glands
 inactive till puberty & taper off in activity in elders
 secretions contain pheromones (play a role in courtship
& social behavior); dogs are notorious for sniffing these
secretions
 secretions are thicker, stickier and produce more odorous
sweat  bacteria break sweat
down into acids
 found deep in dermis and secrete
fluid into tiny canals of hair follicles
b) Eccrine:
 found everywhere;
concentrated in armpits,
orehead, palms & soles of
eet
 composed of salt
& H20  activity, amount &
distribution
s genetically determined
 not as deep in dermis and
secrete into pores
Eccrine Sweat Glands
 allow chemicals causing food odors leak out
of the body
 bacteria feed off nutrients in sweat 
causing odors
 antiperspirants reduce amont of sweat
produced by glands  reduce dampness &
odors
 (-) charged ingredients repel (-) charged
sweat molecules
Nerves
Sensory receptors:
 communicate information from the
environment
to the body
 found in
all skin layers;
concentrated
in dermis &
fascia
Types of Sensory Receptors
Free nerve endings:
• detect pain
• in the epidermis
Types of Sensory Receptors
Meissner’s corpuscles:
• in dermis
• detect
touch
dermal
papillae
--------------Also 
Krause end bulbs (cold temp.)
Types of Sensory Receptors
Pacinian corpuscles:
• deep in dermis &
hypodermis
• detect strong
pressure
(vibrations)
-------------------also  Ruffini
receptors
Nails
 nail root lies beneath cuticle (skin fold)
 keratocytes in nail root move up, die &
flatten  forms
nail body
 lunula- moon
shaped whitish area
 nails grow 1/8 in/mo.
faster than toenails
Hair
 each strand of hair grows from a hair follicle
(inward protrussion of epidermis)
 hair papilla (base
of follicle) has its own
blood & nerve supply
 hair shaft - dead,
hardened, keratinized
stratum corneum-like
cells
Layers of Hair
 3 layers  cuticle, cortex & medulla
cuticle  thin, colorless, protects cortex &
scales point toward tip; large in humans
 cortex 
strength, color
& texture
 medulla 
only present in
thick hair; small
or non-exsitent in humans
Hair Structure
Cuticle – outer coating composed of overlapping scales
Cortex – protein-rich structure around
the medulla that contains pigment
Medulla – central core
(may be absent)
The structure of hair has been compared to that of a pencil with the
medulla being the lead, the cortex being the wood and the cuticle
being the paint on the outside.
http://www.videojug.com/interview/csi-and-trace-evidence-2
Hair
 color determined by
melanin
 amount & location
determines color 
genetically controlled
 arrector pili muscle
(smooth muscle) attachs
to hair follicle  causes
goosebumps (traps heat)
Drugs & Hair
 capture many
chemicals (drug/poison)
that pass through blood
 advantages: 1) goes
back months not days
2) non-invasive, 3) holds
up in court
 disadvantages: 1)
expensive, 2) takes time
to get results
Stages of Hair Development:
Root must be present in order to test hair evidence
for DNA
Anagen: growing
Catagen: at rest
Telogen: dying
44
Habits & Hair Loss
 hair loss is a slowing down of hair growth and
replacement
 physical stress is a major cause of hair loss (childbirth,
illness, injury, pregnancy, and too much exercise
 when body has to use its energy to cope with stress to
places hair growth as a lower priority
 malnutrition and under-nutrition (diets low in amino
acids)
 increase in male hormones
 tight braids or ponytails might also pull off hair faster
than it can be replaced
 excessive hair combing
 emotional stress seems to accelerate growth
Concept Check Questions 10-12
10. What are skin appendages? Provide 4 examples.
- assist skin perform functions; hair, nails, glands,
muscles, nerves
11. The dermis has the ability to regulate heat.
Describe 2 ways the dermis does this.
When hot  BV expand to release heat; releases sweat
When cold  BV contract to retain heat.
12. What do ceruminous & sebaceous glands produce
and how do these secretions differ in function.
- ceruminous glands  cerumen (wax)  clean ear
- sebaceous glands  oil (fats)  lubricate skin & hair
Concept Check Questions 13-15
13. Describe how appocrine & eccrine glands differ in
location and what they secrete.
- appocrine – secrete odorous sweat-like material; armpits,
genitals (can contain pheromones)
- eccrine – secrete H2O, salts, ammonia; all over the body
14. What is the general function of nerves/receptors
in the skin? Name 3 & state what each detects.
communicate info from environment to body
- free nerve endings  pain Meisners corpuscletouch
- Pacinian corpuscle  pressure
15. Describe the differences btwn the 3 layers of hair.
- cuticle – outer layer; protects cortex & medulla
- cortex – middle layer; contains pigments; provides strength
- medulla – inner layer; usually only present in thick hair
Concept Check Questions 16-18
16. Why doesn’t a hair cut hurt, but pulling a hair
out of the head does?
- visible hair is made out of dead cells; hair root is living
17. What does the arrector pili muscle attach to and
what’s its function?
hair; allows hair to stand erect and trap in hot hair
18. What are the advantages & disadvantages of the
testing hair samples for drugs?
Advantages – 1) detects up to months not days, 2) holds
up in court, 3) non-invasive
Disadvantages – 1) expensive, 2) takes a long time to get
results
Burns
 causes skin to lose ability to maintain
homeostasis
 majority of
burnssun
exposure &
cooking accidents
 other causes
chemicals,
electricity, fires
& steam
Types of Burns

Degree  superficial damage;
reddening and swelling
 chemicals, steam, flame
heat & mild sun exposure
st
1
http://videos.howstuffworks.com/howstuffworks/131-how-sunburns-work-video.htm
Types of Burns

Degree  stratum germinativum &
dermal papillae damaged; blisters, fluid
buildup, painful, long healing time; 
longer exposure to previous factors
nd
2
Types of Burns
 3rd Degree  stratum germinativum
not available for healing; dermis, adipose,
muscle, nerve & bone damage; 
excessive exposure to previous factors
Rule of Nines:
method to
determine extent
of a burn injury
Wellness and Illness over the Life Span
Skin pathology can be categorized as:
• degenerative
(diseases that progressively deteriorate skin)
• genetic
(inherited; mutations)
• infectious
(contagious, microorganisms)
Degenerative Skin Disorders
 freckles or solar lentigene (age spots) 
sun exposure
 dermatitis (eczema)
skin inflammation
caused by allergic rxn
or irritant
Degenerative Skin Disorders
 skin cancer  has an underlying genetic
component
 moles 
flat squamouscell tumors;
heavily
pigmented by
melanocytes
http://videos.howstuffworks.com/sciencentral/4149-how-not-gettingenough-sun-can-be-harmful-video.htm
Degenerative Skin Disorders
 skin tags  soft, colored, knob-shaped
tumors that grow out of skin (neck, armpits,
body); surgery can easily remove
Genetic Skin Disorders
 acne, cysts, boils 
hormonal changes causes
overproduction of sebum
around hair follicles
 psoriasis  inflammation
of skin and increased skin cell
production; dry, itchy;
environmentally trigged??
Genetic Skin Disorders
 port wine stains
& spider veins 
common birthmarks
 vitiligo  white
spots on skin;
decrease in melanin
production (immune
attack on melanocytes
???)
Infectious Skin Disorders
 MRSA  caused by Staphylococcus
aureus bacteria; produces destructive
secretions that erode and inflame skin
Infectious Skin Disorders
 Ringworm (tinea)  skin fungus that
eats keratin rich materials
 human papilloma
virus (HPV) group of viruses that cause
various types of warts in
humans
Aging of the Integumentary System
Aging is due to:
• intrinsic factors
(natural decline; genetic, maturation, stress)
• extrinsic factors
(environmental factors, contracting disease, pollution)
• lifestyle can accelerate aging
 loss of head hair
 graying/whitening of hair, decrease in sweating
 excessive growth of hair, loss of fat
 wrinkles; drying out of skin = decrease in oil
Concept Check Questions 19 - 21
19. Explain how the 3 categories of skin burns differ?
- 1st degree – superficial damage – reddening, swelling
-2nd degree – stratum germinativum damage - blisters
-3rd degree – dermis is damaged – nerve damage
20. According to the rules of nines, what % of my
body would be burned if the anterior part of 1 leg,
both sides of my right arm, and my head were burnt?
27%
21. How do the 3 categories of skin disorders differ?
-degenerative – progressive deterioration of skin
- genetic – inherited / mutations in DNA
- infectious - microorganisms
Concept Check Questions 22-24
22. Describe 2 types of degenerative skin conditions.
freckles & solar lentigene (age spots)  too much sun
dermatitis –> dry irritation of the skin
skin cancer –> abnormal, malignant growths of skin
23. Describe 2 types of genetic skin conditions.
Acne  infected sebaceous glands
Psoriasis  inflammation of skin
Port wine / vitiligo  birthmarks, reduced melanin
24. How do the 2 major categories of skin aging
differ?
Extrinsic environmentally triggered
Intrinsic  natural / genetic causes
CSI Investigation
1. Name at least 3 symptoms your patient is suffering
from.
elderly, obesity, high blood pressure & open sore
2. Based on these symptoms, what might your patient
be suffering from?
decline of blood vessels associated with prolonged /
untreated diabetes
3. Explain why/how the dermis became exposed in
her sore?
continous high blood-sugar levels cause smaller blood
vessels in the skin to break down; skin can’t produce
epidermis (and make S.Corneum layer that sheds with
physical damage)
CSI Investigation
4. Why would such an “ugly” sore not cause any pain
sensation?
Sore is deep in the skin; all nerves and receptors have been
damaged.
5. As her personal trainer, why would you recommend
an exercise program for this patient? What would her
program entail?
Routine should include exercise that reduces weight and
increases blood flow. Inflexible skin may cause restriction
movements. Increase the amount of protein  build
immune system and provide S.germinativum with amino
acids required for normal rate of mitosis.
CSI Investigation
 exercise program  increase weight
loss & increase blood flow  inflexibility
of skin may cause movement
restrictions??
 sores in elders are common 
natural decrease in blood flow
 increase protein  provides stratum
germinativum with amino acids to divide
 avoid stress on body  reduces
immune response and will slow healing