Integument(Skin)
Integument is nothing
but the skin.
 Integument(=to cover
in latin
 Skin and its appendages
are the largest organ of
the body
 Functions:
1. Protection
2. Heat regulation
3. Sensation
4. Synthesis and storage
of Vit D

Integumentary
system
Skin along with the
 exocrine
gland(sebaceous
gland
 Hair
 Nails
 Associated blood
vessels and
 Associated nerves
Comprise
integumentary system
Skin
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Superficial epidermis
middle dermis
Deep
hypodermis(superficial
fascia)
Epidermis

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Superficial layer
composed of
keratinized stratified
squamous epithelium
Avascular with no
blood vessels or
lymphatics
Has basal cells which
has regenerative
capacity
Thick skin has 5 layers
of cells
Thin skin has 4 layers
of skin
Dermis

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Middle layer
composed of Dense
irregular connective
tissue
Contains nerve
endings,hair follicles,
and glands
They nourish the
avascular epidermis
Contains dermal
papillae(projections
of dermis into
epidermis)
Langer(incision or tension)
lines in skin


They are the direction
in which the most
collagen fibres run in
any particular location
in the skin.
Incision should be
made parallel to the
direction to avoid
minimal scarring.
Hypodermis



Deepest layer
Stores fat and anchors
upper layers to other
tissues
Composed of areolar
and adipose
connectieve tissue
Epidermal layers
From base to top
 Stratum basale
 Stratum spinosum
 Stratum granulosum
 Stratum lucidum
 Stratum corneum
Stratum basale
Single layer of columnar or cuboidal cells
resting on basement membrane
 The epidermis is renewed every 15-30
days; proliferative activity takes place in
this layer; cells are very mitotic

Stratum spinosum
several layers of polygonal shaped cells
with spines.
 Spines are nothing but keratin filaments.
 It resists the effects of abrasion and the
layer is thicker in thick skin which is
subjected to continuous friction and
pressure(eg: soles and palms)

Stratum granulosum
3-5 layers of flattened polygonal cells with
visible granules
 Cells undergo keratinization which is a
process in which nucleus shivels up, cells
dies, and cell fills up with protein keratin
 This layer acts as a barrier to penetration
by foreign materials and provides sealing
effect

Stratum lucidum
 2-3 layers of dead, anucleated, clear cells.
Only found in thick skin
Stratum Corneum
 20-30 layers of dead, anucleated cells.
 They are cornified( brittle, hardened).
These outer cells are constantly shed
Epidermal cells
Keratinocytes: most numerous(90%);found
in all layers; produces keratin which
provides the protective barrier
mechanically as well as immunologically
Melanocytes: 2nd most
numerous(8%);found in stratum
basale;produces melanin which is a
photoprotector
Epidermal cells

Merkel cells: 3rd numerous(1%) found in
stratum basale;provides tactile(light
touch) sensation

Langerhans cells: <1% found in stratum
spinosum; phagocytic action
Dermal layers
Pappillary Layer:
uppermost; composed of
dermal papillae;
contatains blood vessels,
sensory receptors, ducts
of glands; and hair shafts
Reticular Layer:
deepest;contains blood
vessels; sensory
recptors(neurons);
secretory poertions of
glands and hair follicles
Epidermal derivatives(skin
appendages)
Hair : contains bulb, root and
shaft ; associated with
arrector pili muscle; functions
to protect UV light, trauma,
and heat loss
Nails : formed from stratum
corneum ; functions in
protection and grasping
Exocrine Glands:
1. Sebaceous glands
2. Sweat (sudoriferous)
glands
3. Ceruminous
Exocrine glands in skin
Sebaceous glands(sebum=oil):associated
with hair follicles and functions in
lubrication and bactericidal
 Sweat(sudoriferous) glands:

 appocrine: in axiallary and pubic regions,
secreates onto hair shafts and release an
odiferous secretion
 Eccrine : found everywhere, funtioning to
release perspiration
 Ceruminous: modified sweat glands ; found in
external auditory canal; cerumen is an insect
repellent and a water proofing agent