Download The integumentary system

The Integumentary system
Chapter 5
The Skin
• Most accessible organ/system to the outside
world
• 16% of total body weight
• Constantly under attack from the environment
• The human body’s first line of defense.
The integument
• Body covering
• Interconnected with blood vessels and
sensory receptors.
Two Major Components
1. Cutaneous membrane
2. Accessory structures
Cutaneous Membrane
Accessory Structures
Epidermis
Dermis
Hair, nails, exocrine glands
Superficial
Underlying
connective
tissues
Primarily found in the dermis
but protrude (poke through)
the epidermis.
Blood Vessels
Nerves
Glands
Yet another layer. . .
• Below the dermis you can find the
hypodermis or subcutaneous layer
– Various connective tissues that separate the skin
from other organs
ie: muscles and bones
Skin Functions
•
•
•
•
1. Temperature
2. Sensory
3. Moisture Control
4. Protection
Skin Functions
1.
2.
3.
4.
5.
6.
7.
8.
Protection – separate inside from outside
Excretion
salts, water, wastes
Maintenance
body temperature
Produce melanin
Produce keratin
Synthesize vitamin D
Store lipids and various fat cells
Detect sensation
touch, pressure, pain,
temperature
The Epidermis
• Upper skin surface
• Protective, keeps micro-organisms out
• Avascular
– Having no blood cells
Made up mostly of keratinocytes (contain large
amounts of proteins)
Thick skin vs. Thin skin
Thin Skin
• Covers most of the body
• Has 4 layers
• About the thickness of a
plastic sandwich baggie
Thick Skin
• Found on the palms and
soles of feet
• And the soles of your feet
• Contains an extra layer
• About the thickness of a
paper towel
Layers of the Skin
• Stratum Germinativum
• Major layer of the skin containing multiple
different cell types
Basal Cells
Melanocytes
Merkel Cells
Basal Cells –
stem cells that become keratinocytes
Melanocytes –
produce melanin (skin pigments responsible
for skin tone)
Merkel Cells –
Sensitive to touch
The other skin layers . . .
1.
2.
3.
4.
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum germinativum
or Stratum basale
Dermis
The Life of Skin
• Cells move from layer to layer
• This process takes between 15-30 days
– Stratum germinatvum
stratum corneum
• Last about two weeks before they are shed
Skin Color
2 factors
1. Pigments found in the epidermis
2. Circulation through the dermis
Pigments
Carotene
• Orange-yellow pigment
• In fatty tissues
• Tends to be more dominant
in light skinned individuals
Melanin
• Brown, yellow, or black
pigment
• Aide in protection and use
of UV radiation
Dermal Circulation
• Blood flows through the dermis adding a pink
hue to the skin
Epidermal fun facts
 When the blood supply to the skin is reduced, the
skin turns pale.
 Embarrassment usually causes a rush of blood to
the surface blood vessels resulting in a flushed
appearance.
 Sustained circulatory reduction causes cyanosis blue lips and fingernails. (caused by cold, heart
attack, oxygen depletion).
UV exposure causes melanocytes overproduction (tan) and the production of vitamin
D3 or cholecalciferol.
The liver converts this to a hormone
called calcitriol which is necessary for normal
Ca and P absorption in the small intestine.
The Dermis
• Lies between the epidermis and subcutaneous
• Has capillaries, connective tissues, and glands
• Sensory nerves
a. Nociceptors
 Fast pain—sharp (deep cut, needle)
 Slow pain—burning, aching, throbbing
Thermoreceptors.
 Free nerve endings
 3 - 4 x more cold receptors than warm
Accessory Structures
I.

Hair
Nonliving—produced in follicles

- 98% on general body surface (not head)

- lose 50/day.
• 3 types:
lanugos (prenatal)
vellums (peach fuzz—most of the body)
terminal (heavy, usually deeply pigmented, head).
Glands - two types of exocrine
glands: Sebaceous & Sweat.
A. Sebaceous glands (oil glands).
 Secretes sebum
 Sebum—inhibits bacterial growth, lubricates
hair and skin.
Sweat glands
Apocrine sweat glands are found in the arm
pits, groin, nipples.
This secretion along with bacteria yields 2,3
hexonoic acid.
Merocrine sweat glands are more numerous
and more widely distribute.
Adults—2.5 million, high concentration in
palms of hands.
Modified sweat glands: mammary glands milk /ceremonious glands - ear wax
Nails –
dead, tightly compressed cells packed with keratin.
Protect exposed tips of fingers and toes.
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$$
 Review integumentary repair
 Review the integration of the integumentary
system with other systems
 Review burns and grafts
Burns
• 1st Degree Burn
• - superficial (involves the epidermis)
- painful, tender and swollen
• 2nd Degree Burn
• - partial thickness (involves the dermis and
above)
- painful, discolored, blisters, oozing liquid
• 3rd Degree Burn - full thickness burn (beyond
the dermis) - not painful, charred(black), or
white.