anatomy of the skin

1. SKIN ANATOMY
ANATOMY OF INTEGUMENTARY
SYSTEM
Prepared by:
Mr.Maulik chaudhary

2. Contents
• 1) Structure of the skin
• 2) Functions of the skin
• 3) Wound healing

3. Function of skin
• protects the underlying structures from injury
and from invasion by microbes
• contains sensory nerve endings that enable
discrimination of pain, temperature and touch
• is involved in the regulation of body
temperature.

4. Structure of the skin
• The skin is the largest organ in the body and has a
surface area of about 1.5–2 m2 in adults.
• In certain areas, it contains accessory structures:
glands, hair and nails.
• Anatomy of skin layers:
• 1) epidermis = is the thinner outer covering
• 2) dermis= is the thicker middle layer of the skin
composed connective tissues.
• 3) subcutaneous layer = composed of areolar tissue
and adipose (fat) tissue.

6. Epidermis
• The epidermis is the outer and thinner region of the
skin.
• It is made up of stratified squamous epithelium
divided into several layers;
 the deepest layer is the stratum basale
(germinative layer)
 the most superficial layer is the stratum corneum.

7. • It varies in thickness, being thickest on the palms of
the hands and soles of the feet.
• There are several layers (strata) of cells in the
epidermis which extend from the deepest
germinative layer to the most superficial stratum
corneum (a thick horny layer)

8. • Epidermal cells originate in the germinative
layer and undergo gradual change as they
progress towards the skin surface.
• cytoplasm has been replaced by the fibrous
protein= keratin.
• Complete replacement of the epidermis takes
about a month.

9. Healthy epidermis depends upon three processes being
synchronised:
1) desquamation (shedding) of the keratinised cells
from the surface
2) effective keratinisation of cells approaching the
surface
3) continual cell division in the deeper layers with
newly formed cells being pushed upwards to the
surface.

10. • Skin colour is affected by various factors.
• Melanin, a dark pigment derived from the
amino acid tyrosine and secreted by
melanocytes in the deep germinative layer,
• is absorbed by surrounding epithelial cells.
The amount is genetically determined and
varies between different parts of the body,

11. Dermis
• The dermis, is a deeper and thicker region
than the epidermis, is composed of dense
irregular connective tissue.
• The upper layer of the dermis has fingerlike
projections called dermal papillae.
• Dermal papillae project into and anchor the
epidermis.

12. • In the overlying epidermis,dermal papillae cause
ridges, resulting in spiral pattern commonly known
as “fingerprints’.
• The function of the epidermal ridges is to Increase
friction to provide a better ‘grip’.
• Because they are unique to each person, fingerprint
and footprints can be used for identification
purposes.

13. The dermis layer contains following:
• blood and lymph vessels
• sensory nerve endings
• sweat glands and their ducts
• hairs, arrector pili muscles and sebaceous
glands.

14. Blood and lymph vessels.
• Arterioles form a fine network with capillary
branches supplying sweat glands, sebaceous glands,
hair follicles and the dermis. Lymph vessels form a
network throughout the dermis.
Sensory nerve endings.
• Sensory receptors (specialised nerve endings)
sensitive to touch, temperature, pressure and pain
are widely distributed in the dermis.

16. The Appendages of the Skin:
The appendages of the skin are:
1) the nails
2) the hairs
3) the sweat glands
4) sebaceous glands with their ducts.

17. • A sweat gland is tubular. The tubule is coiled, particularly at its
origin within the dermis.
• These glands become active when a person is under stress.
Two types of sweat glands are present:
1) Apocrine
2) Eccrine
• Apocrine glands open into hair follicles in the anal
region, groin, and armpits. These glands begin to secrete at
puberty.
Sweat Glands

18. • Eccrine glands open onto the surface of the skin.
• They become active when a person is hot, helping to lower
body temperature as sweat evaporates.
• Therefore, sweat is a form of excretion. Ears contain
modified sweat glands, called Ceruminous glands, which
produce cerumen (earwax).

20. Hairs
• These grow from hair follicles, downgrowths of
epidermal cells into the dermis or subcutaneous
tissue.
• At the base of the follicle is a cluster of cells called
the hair papilla or bulb.

21. Sebaceous glands
• These consist of secretory epithelial cells derived
from the same tissue as the hair follicles.
• They secrete an oily antimicrobial substance= sebum,
into the hair follicles and are present in the skin of all
parts of the body except the palms of the hands and
the soles of the feet.

22. Nails
• Human nails are equivalent to the claws,
horns and hooves of animals.
• Derived from the same cells as epidermis and
hair these are hard, horny keratin plates that
protect the tips of the fingers and toes.

23. Functions of the Skin
Immunological function
Secretory function
Thermoregulation function
Receptory function
Excretory function
Protective function