INTEGUMENTARY
SYSTEM
Parts, Function,
Appendages + Fascia.
Learning Objectives
After completing the demonstration,
the student will be able to :
• Define the term integumentary system.
• Discuss the function of the skin .
• Differentiate between epidermis & dermis.
• Discuss the significance of tension lines.
• Discuss the main determinant of skin
color.
• Identify the appendages of the skin.
• Differentiate between superficial & deep
fascia.
Integumentary System
• The integumentary
system is the organ
system consisting of
the skin and its
associated structures,
(hair, nails, sweat
glands, and sebaceous
glands) that cover and
protect the body.
Functions of the skin
• Maintenance of homeostasis and thus to
survival.
• Protection:
Protects the underlying tissues against the
invasion by microorganisms, entry of most
harmful chemicals, mechanical trauma, from
dehydration caused by loss of internal body
fluids.
Functions of the skin
• Sensation, growth and
synthesis of important
chemicals and hormones
( such as vitamin D ).
• Excretion, temperature
regulation and immunity.
The Skin
• The Body’s largest,
thinnest, and one its
most important organs.
• Two Primary Layers
compose the skin:
– Epidermis – Superficial,
thinner layer.
– Dermis – the deep,
thicker layer.
Thin and thick skin
• Most of body surface is
covered by thin skin.
• Thick skin is the
hairless skin covering
the palms of the hands
(and fingertips), soles of
the feet and other body
areas subject to friction.
Skin Thickness
Total skin thickness varies
from 0.5 mm in areas
such as eyelids to more
than 5 mm over the back.
The Epidermis
A Superficial Cellular Layer
• Epidermis is a
keratinized Epithelium
– has a tough, horny
superficial layer that
provides a
protective outer
surface.
– Overlies the
pigmented deep or
basal layer.
The Epidermis
(A Superficial Cellular Layer)
• Has no blood vessels or
lymphatics.
• Nourished by the
underlying vascularized
dermis.
• Its main function is
protection, absorption
of nutrients, and
homeostasis.
The Epidermis (Cell Types)
Composed of several types of
epithelial cells.
• Keratinocytes:
– Filled with fibrous protein
Keratin.
– Form the principal structural
element of the outer skin.
• Melanocytes:
– Contribute color to the skin.
• Langerhan cells:
– Dendritic cells that play a role
in immunity
The Epidermis (Cell Layers)
Strata of epidermis from deepest
to most superficial are:
– Stratum Basale (base layer).
– Stratum Spinosum (spiny layer).
– Stratum granulosum (granular-
layer).
– Stratum lucidum (clear layer)
– Stratum corneum (horny layer).
Dermal – Epidermal
Junction
• A specialized area
between the epidermis
and dermis called the
epidermal – dermal
junction.
• Composed chiefly of a
basement membrane.
• Junction ‘glues’ the two
layers together and
provides mechanical
support for the epidermis.
The Dermis
(Deep Connective Tissue Layer)
• Dermis or corium is
sometimes called the
“true skin”.
• Mechanical strength
of the skin is in
dermis.
• Dermis provides a
reservoir or storage
area for water and
important electrolytes.
The Dermis
(Deep Connective Tissue Layer)
• Composed of a thin
papillary and a thicker
reticular layer.
• Dermis is much thicker
than the epidermis and
may exceed 4mm on the
sloes and palms.
The Dermis
• Somatic sensory
receptors process
sensory information such
as pain, pressure, touch
and temperature.
• A variety of muscle
fibers, hair follicles,
sweat and sebaceous
glands and many blood
vessels extend at various
levels of the dermis.
• Rich vascular supply of
the dermis plays a critical
role in the regulation of
body temperature.
Hypodermis
(Subcutaneous Layer, Or Superficial Fascia)
• Not part of the skin, but
lies deep to the dermis
thus forms a connection
between skin and
underlying structures.
• Hypodermis is mostly
loose fibrous and
adipose tissue.
• Fat content of the
hypodermis varies with
the state of nutrition and
in obese individuals may
exceed 10 cm in
thickness in areas.
Tension lines of skin
(cleavage lines or langer lines)
• Are due to due to the
patterns of arrangements
of collagen fibers in the
dermis.
• Tends to spiral
longitudinally over limbs
and run transversely in
neck and trunk.
• Incision made along the
skin tension lines heal with
minimum scaring.
SKIN COLOR
• Main determinant of skin color
is the quantity of melanin
deposited in the cells of the
epidermis.
• Albino individuals ( Albinism)
have a characteristic absence
of the pigment in their hair,
skin and eyes.
• Yellow pigment beta –
carotene found in many
vegetables and fruits also
contribute to skin color.
Skin appendages
• Skin appendages are
appendages that are
associated with the skin
and serve a particular
function.
• Sweat glands, hair, nails
and sebaceous glands
are all considered
epidermal appendages.
• Hairs (sensation, heat loss, filter
for breathing, protection).
• Arrector pilli (smooth muscles
that pull hairs straight).
• Sebaceous glands (secrete
sebum onto hair follicle to oil the
hair).
• Sweat glands (sweat can be
secreted with strong odour
(apocrine) or with a faint odour
(eccrine)) and nails (protection). 1 Hair shaft
2 Sebaceous gland
3 Bulb
4 Hair papillae
5 Sweat gland
NAILS
• Lunula is the half moon shaped
white area on a nail.
• Anatomical term for the cuticle is
the eponychium.
• Matrix is the region of the nails
where there are dividing cells
and nail growth.
• Nail plate rests on the nail bed.
• Nail root is the proximal portion
of the nail that is underneath
skin.
FASCIA
• Fascias constitute the wrapping , packing,
and insulating materials of the deep structures
of the body .
Superficial fascia
This is found in the
subcutis in most
regions of the body,
blending with the
reticular layer of the
dermis.
E.g. fascia of scarpa.
The subcutaneous inguinal ring.
(Superficial fascia visible at top.)
DEEP FASCIA
• A dense, organized
connective tissue layer,
devoid of fat, that covers
most of the body deep to
the skin and
subcutaneous tissue.
• E.g. Transversalis fascia.
Visceral Fascia
• This suspends the
organs within their
cavities and wraps
them in layers of
connective tissue
membranes.
• E.g. pericardium.
Functions
• Fasciae are normally thought of as passive
structures that transmit mechanical tension
generated by muscular activities or external
forces throughout the body.
• Function of muscle fasciae is to reduce
friction to minimize the reduction of
muscular force. In doing so, fasciae allow
muscles to glide over each other.
Summary
• Integumentary system:
• Skin, consists of the epidermis, dermis, and
specialized structures ( hair follicles, sebaceous
glands and sweat glands ).
• Sweat glands, hair, nails and sebaceous glands
are all considered epidermal appendages.
• Skin plays important roles in protection, heat
regulation, sensation, synthesis and storage of
vitamin D, features tension lines.
REFERENCES
• Clinically oriented Anatomy.
• Sixth Edition
– Keith L. Moore.
– Arthur F . Dally
– Anne M. R. Agur
• Anthony’s textbook of anatomy
physiology .
• 18th edition .
THANK YOU
