The
Integumentary
System is a
dynamic interface
between the body
and the external
environment.
Principle organ - the skin,
or integument.
Associated structures :
hair, nails, glands
• The skin is made up of several types of
tissues that are arranged to function
together. It is the largest organ of the
body, with a surface area of
approximately 2m2 in the average
adult.
• Dermatology is the medical specialty
that deals with the skin.
INTEGUMENT
• Body membranes - thin
sheets of tissue that cover
the body, line body
cavities and cover organs
within the cavities in
hollow organs.
Membranes also line
internal spaces of the
body that open to the
outside of the body.
They can be categorized as
epithelial or connective tissue
membrane.
• There are three types of epithelial membranes:
1. The Cutaneous membrane
2. The Serous membranes
3. The Mucous membranes
There are two types of connective tissue
membranes:
1. The Synovial membrane
2. The Meningeal membranes
EPITHELIAL MEMBRANES
– Contain epithelial tissue and the underlying
connective tissues.
• Epithelial tissues include: squamous, cuboidal, columnar,
and transitional cells with a simple or stratified
arrangement
• 3 Main Types of Epithelial Membranes
1. Cutaneous Membrane-the skin
2. Serous Membrane-lines body cavities and
covers organs
3. Mucous Membrane-lines the internal spaces
that open to the outside of the body
Cutaneous membrane ( the
skin) is discussed in depth
later
Serous Membrane Structure:
consist of consists of a single
layer of simple squamous
cells which produce the
lubricating serous fluid and
the connective tissue to which
it is attached
– Connective layer- Basement
membrane that holds and
supports the epithelial cellsprovides the blood vessels and
nerves for the secretory
epithelial cells, and serves as
the binding layer which allows
the whole serous membrane to
adhere to organs and other
structures.
Serous Membrane
• Line body cavities that do not open directly to the
outside and cover the organs located in those cavities.
• Serosa is covered by a thin layer of serous fluid that is
secreted by the epithelial cells.
– Serous fluid lubricates the membrane and reduces friction and
abrasion when organs in the thoracic or abdominopelvic cavity
move against each other or the cavity wall.
•
Serous membranes have special names given according
to their location. For example, the serous membrane that
lines the thoracic cavity and covers the lungs is called
pleura.
Three main serous cavities within the human
body.
• Pericardium found within the
thorax and
provides a lining
around the heart.
Pleural cavity -The
pleura are made up
of two cavities that
line the lungs.
contains the lungs.
The peritoneum
lines the
abdominal region
and provides a
cover for the
stomach, liver and
intestines
Each serous membrane is made up of two distinct
layers - the parietal layer and the visceral layer.
•Parietal Layer - the outer layer of the membrane
that is attached to surrounding tissues in the cavity.
•Lines the walls of a body cavity.
•Visceral Layer - the inner layer that covers the
organs.
The two layers are separated by a thin layer of fluid, called
serous fluid, which acts as a lubricant and reduces friction
between organs and other organs or tissues.
Inflammation of
the pleurathe serous membrane lining of the
pleural cavity.
Inflammation of the
peritoniumthe serous membrane which lines
part of the abdominal cavity.
Inflammation of the
pericardium- the membrane
lining of part of the thoracic cavity
and covers the heart
Mucus Membrane
Line the body
cavities that
open to the
outside,
including
.
Consist of a mucus-forming epithelium that is
attached to an underlying connective tissue.
The epithelial layer(s) vary in structure depending on
the location.
The moisture found in a mucous membrane acts to protect the body
by creating a barrier which can trap pathogens, dirt, and particulate
matter so that they can be trapped and eliminated by the body.
Mucus can also act as a lubricant, and it facilitates gas
exchange and absorption in the lungs.
The absorption qualities of mucous membranes are important
in the digestive tract, where the body pulls necessary nutrients
out of food.
Many toxins and other harmful substances can be quickly
absorbed through the mucosa.
Connective Tissue Membranes
The Synovial membrane
• Connective tissue membranes that line the cavities
of the freely movable joints such as the shoulder,
elbow, and knee.
• Secrete synovial fluid
into the joint cavity,
which lubricates the
cartilage on the ends
of the bones so that
they can move freely
and without friction.
The Meningeal membranes
• The meninges are three connective tissue
membranes that lie just external to the brain and
spinal cord. From external to internal, the
meningeal layers are the Dura mater, the
Arachnoid and the Pia mater. More on this later.
The Cutaneous Membrane—the Skin
– Cutaneous
membrane
• Epidermis –
epithelial tissue
• Dermis –
connective
tissue
– Accessory
Structures
• Glands
• Hair (hair
follicles)
• Nails
– Subcutaneous Deep to skin – not
part of skin: the
hypodermis
• The Epidermis
-Keratinized, stratified
squamous epithelium
-Contains no blood
vessels
-4 types of cells
Has 4-5 distinct strata
(layers) of cells
Thick vs. thin skin
• The epidermal layers
move up the strata
changing shape and
composition as they
differentiate and
become filled with
keratin, a tough
fiberous structural
protein.
• The outermost layer of the
epidermis made up of
dead cells that contain
keratin. The thickness of
the stratum corneum
varies according to the
amount of protection
and/or grip required by a
region of the body.
• Stratum lucidum- found
only in areas of thick skin,
ie. palms of the hands and
soles of the feet.
• Stratum granulosum- (or
granular layer) have lost their
nuclei and are dying. Keratin
proteins and water-proofing
lipids are being produced and
organized in this layer.
• Stratum Spinosum – these cells
start to synthesize keratin and
change from being columnar to
polygonal.
• Stratum germinativum (or
stratum basale) -the deepest
layer where cell division occurs.
This layer regenerates the layers
of the epidermis.
The Dermis
• The dermis varies in thickness depending on the
location of the skin, but is thicker than the
epidermis
• It is composed of three types of tissue:
• collagen
• elastic tissue fibers
• reticular fibers.
The two layers of the dermis are the papillary and reticular
layers.
Papillary Dermis
• the uppermost layer of the dermis.
• Composed of fine and loosely
arranged collagen fibers.
– Collagen is the main component of
connective tissue, and is the most
abundant protein in mammals
Make fingerprints and
footprints
Improves grip
• It is named for its fingerlike
projections called papillae, which
extend toward the epidermis. The
papillae provide the dermis with a
"bumpy" surface that protrudes into
the epidermis, strengthening the
connection between the two layers of
skin.
Collagen and elastin
fibers in Scanning
electron microscopy
Dermal papilla in
scanning electron
microscopy
Reticular Dermis
• The lower layer of the
dermis.
• Composed of thick, densely
packed collagen fibers, and
dermal elastic fibers.
– elastic fibers are bundles of
elastin proteins found in the
extracellular of connective
tissue. These fibers die with
age.
This layer is important in giving the skin
strength and elasticity, as well as housing
other important epithelial derived structures
such as glands and hair follicles.
Cross section of the dermis
HYPODERMIS (or
SUBCUTANEOUS layer)
• Under the dermis- composed of loose
connective tissue and adipose tissue.
• Function:
– insulation (helps to regulate
temperature)
– shock absorbers (help protect
underlying layers)
– stores lipids .
• The hypodermis also contains larger
blood vessels
• The hypodermis is 810% thicker in females
than in males due to the
greater number of
adipocytes and is likely
hormonally influenced.
Ovulation may be
disturbed in women
with low fat reserves
and the softening of the
body contours in
females plays a part in
sexual attraction.
Link hypodermis