Basic anatomy of skin and its layers with skin appendages

1. SHAZIA REHMAN
Integumentary system

2. INTEGUMENTARY SYSTEM
▪ The INTEGUMENTARY SYSTEM includes
all the structures and tissues related to the
skin.
▪ This includes:
1. skin
a. Epidermis
b. Dermis
2. accessory organs
a. Hair
b. Nails
c. Glands

3. Skin is the largest organ of the body. It
has an area of 2 square metres (22
square feet) in adults, and weighs
about 3 to 5 kg. The thickness of skin
varies from 0.5mm thick on the
eyelids to 4.0mm thick on the heels of
your feet.

4. Functions
▪ Protection
▪ Sensation
▪ Allows movement
▪ Synthesis
▪ Excretion
▪ Immunity
▪ Temperature Regulation

5. Anatomy of the Skin

6. Epidermis
▪ Outer layer of stratified squamous
keratinized epithelium
▪ Is multilayered.
▪ Is AVASCULAR (no blood vessels)
▪ Has no nerve tissue (can’t feel pain)
▪ Thickness: vary according to body part
in eyelid 0.05mm & in the palm of hand
1.5mm

8. Stratum Corneum
▪ This layer consists of 15-30 layers of dead
keratinized cells.
▪ This dry, dead layer helps prevent the
penetration of microbes and provides a
mechanical protection against abrasion for the
more delicate, underlying layers.
▪ Cells in this layer are shed periodically and
are replaced by cells pushed up from the
stratum granulosum
▪ They are shed every four weeks.

9. Stratum Lucidum
▪ This layer has closely packed
keratinocyte cells with seleiden, a
clear protein rich in lipids.
▪ This is the thick skin that you find in
your palms and feet and its
transparency is due to seleiden.

10. Stratum Granulosum
▪ This layer is composed of 3-5 layers of
Keratinocytes. It appears grainy due to the
changes in keratinocytes that are being pushed
to this layer.
▪ The cells become flatter, their cell membranes
thicken, and they generate large amounts of
the proteins keratin.

11. Stratum Spinosum
▪ This layer is composed of daughter
keratinocytes and dendritic cells,
which fight infections in the body.
▪ Stratum spinosum is shiny in
appearance due to protruding
structures called desmosomes.

12. Stratum Basale
▪ This is the lowest layer of epidermis and is
composed of keratinocytes, melanocytes and
tactile cells.
▪ Keratinocytes produced here constantly
undergo cell division and are pushed to the
upper layers of the epidermis.
▪ Melanocytes produce melanin, a brown
pigment that is responsible for skin coloration
and protecting against the harmful effecte of
UV light.

13. Dermis
▪ The 2nd layer below the epidermis(thick
layer of dense connective tissue)
▪ Contains collagen, elastin, blood vessels
,sebaceous gland, sweat glands and hair
follicles. The nerve endings in the dermal
layer are responsible for the sense of
touch in your body.
▪ It has two sub-layers

14. The Papillary Layer
▪ The upper, papillary layer, contains a
thin arrangement of collagen fibers.
The papillary layer supplies nutrients
to select layers of the epidermis and
regulates temperature.
▪ This layer forms blunt conical
projection, called Dermal papillae.

15. The Reticular Layer
▪ The lower, reticular layer, is thicker
and made of thick collagen fibers that
are arranged in parallel to the surface
of the skin.
▪ It supports other components of the
skin, such as hair follicles, sweat
glands, and sebaceous glands.

16. Hypodermis
▪ The consists of well-vascularized, loose
connective tissue and adipose tissue. The
deeper tissues including muscle, tendon,
ligament, joint capsule and bone that lie
beneath the hypodermis.
▪ This layer maintains the temperature and acts
like a cushion or shock absorber. The layer
also helps attach dermis to the bones and
muscles.

17. Hair
▪ Hair is an accessory organ of the skin made
of columns of tightly packed dead
keratinocytes /cornified found in most
regions of the body.
▪ The few hairless parts of the body include
the palmar surface of the hands, plantar
surface of the feet, lips, labia minora,
and penis.

19. Hair Shaft: part of your hair that can be seen
above your scalp.
Hair follicle :A tunnel-shaped structure in the
epidermis of the skin. Hair starts growing at
the bottom of a hair follicle.
Bulb: Forms the base of the hair follicle
Hair Papilla: A knoblike vascular indentation
of the bottom of a hair follicle, on which
the hair bulb fits.

20. Arrector pili muscle
These are small smooth muscles attached to hair
follicles. Contraction of these Muscles causes
the hairs to stand on end.
Life span of hair
Lifespan varies in different region
Scalp hair :3-5 years
Eye brow and eyelash :3-5 months

21. Nails
Nails are accessory organs of
the skin made of sheets of
hardened keratinocytes and
found on the distal ends of the
fingers and toes.

22. Parts of nail

23. Nail plate: the visible hard part of the nail
Nail folds: the skin that frames the nail plate
on three sides
Nail bed: (epithelial layer)the skin beneath the
nail plate
Cuticle: the tissue that overlaps your nail plate
at the base of your nail - it protects the new
keratin cells that slowly emerge from the nail
bed
Lunula: the whitish, half-moon shape at the
base of your nail underneath the plate

24. Nail matrix
Root of the nail. Forms nail plate from base of nail
bed
Eponychium
Skin just proximal to cuticle, Binds nail to
underlying skin at proximal margin
Hyponychium
Area beneath free edge of nail, Junction where nail
bed meets tip of digit skin
Perionychium
the tissue bordering the root and sides of a fingernail
or toenail.

25. Sebaceous glands
▪ Sebaceous glands are exocrine glands found in
the dermis of the skin that produce an oily
secretion known as sebum.
▪ Sebum is produced in the sebaceous glands
and carried through ducts to the surface of the
skin or to hair follicles.

26. Sebaceous glands are found in every part of
The skin except for the thick skin of the
palms of the hands and soles of the feet.
Function:
▪ Lubricates and protects the skin

27. Sweat glands (sudoriferous gland )
The body of the gland is made up of a coiled tube,
surrounded by a good blood supply, and a duct,
which opens onto the skin surface through a
pore(sweat pore).
Sweat glands are found throughout the skin but are
more numerous in areas such as the soles of the feet,
palms of the hand, armpits and groin.
Sweat that helps flush out toxins from the body,
keeping it cool.