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The Integumentary
System
Amanda Dunne
The Integumentary System
The primary functions
Storage (Water, Fat, Vitamin D)
Regulation of body temperature
Prevention of dehydration (water loss)
Layers:
Epidermis (superficial)
Dermis (deep)
Hypodermis (Subcutaneous)
Structure of human skin
Epidermis
Thinnest most superficial layer
Critical barrier against the outside world
Consists of several layers of varying thickness
This layer determines the thickness or thinness
of the skin.
Can you guess where the thickest and thinnest
layers might be?
What does the epidermis
contain?
Keratinocytes
Keratin producing cell with gives skin its protective properties
Melanocytes
Pigment (Melanin) producing cell which gives skin its colour
Langerhans cells
Immune cells
Merkel cells
Sensory nerve cells providing sensation for touch
Layers of the epidermis
The epidermis consists of
five sub-layers that work
together to continually
rebuild the surface of the
skin
Stratum corneum
Lucid layer
Granular layer
Squamous cell layer
Basal cell layer
1. Basal cell layer
Deepest layer which contains young keratinocytes
Also called germinative layer because these cells are
constantly dividing. This pushes the older cells to the surface.
Contains melanocytes which secrete melanin which protect
this deep layer from sunlight.
2. Squamous cell layer
This layer is the thickest.
Sometimes known as the ‘prickly layer’ because
It contains keratinocytes which appear irregular
and spiny.
Keratinocytes = Keratin, a tough protective
protein
Langerhans cells which alert the immune system
when skin gets damaged
3. Granular layer
Granular layer containing
flattened cells
Pushed upwards towards
the surface
Eventually dehydrate and
die
4. Lucid layer
Clear lucid layer
Pushed upwards towards the surface
Eventually dehydrate and die
Very thin transparent layer
5. Stratum corneum
The outermost (most superficial) layer made up
of 10-30 layers that are continually shedding
Also called ‘horny layer’ because it toughness
resembles animals horns
This layers is continually sloughed off and new
cells push up from underneath
Epidermal Cell turnover
Complete cell turnover
every 28-30 days in adults.
In elderly adults the same
process can take between
45-50 days.
The Dermis
Located underneath the epidermis,
the main functions of the dermis are to:
Regulate body
temperature
Supply the epidermis
with nutrient
saturated blood.
The Dermis
Binds the entire body together like a body stocking
Makes up 90% of skin thickness
Stores most of the body’s water supply
Rich supply of nerve fibres, blood and lymph
vessels
The blood vessels supply nutrients and oxygen to
the skin and take away cell waste.
The blood vessels transport the vitamin D
produced in the skin back to the rest of the body.
Contains most of the skin specialised cells and
structures.
Sebaceous glands
Sebaceous glands secrete
oil that helps keep the skin
smooth, supple and
waterproof.
Protects against bacterial
or fungal overgrowth on skin.
Sebaceous, or oil secreting
glands, are attached to hair
follicles and can be found
almost everywhere on the
body.
Hair Follicles
The hair follicle is a
tube-shaped sheath
that surrounds the part
of the hair that is
under the skin and
nourishes the hair
Hair follicle
Sweat Glands
The average person has about 3 million sweat glands.
Two types:
Eccrine glands - true sweat glands. Found over entire body,
they regulate body temperature by bringing water via the
pores to the surface of the skin, where it evaporates and
reduces skin temperature.
•Apocrine glands specialised and found only
in the armpits and pubic
region. Secrete a milky
sweat that encourages
the growth of the
bacteria responsible for
body odour.
Nerve Endings
The dermis layer also contains pain and touch
receptors that transmit sensations of pain, itch,
pressure and information regarding temperature to
the brain for interpretation.
If necessary, shivering (involuntary contraction
and relaxation of muscles) is triggered, generating
body heat.
Sensory Receptors of the
skin:
The Hypodermis
Also known as the subcutaneous layer
The innermost layer of the skin
Consists of a network of fat and collagen cells.
Functions as an insulator, conserving the body's
heat, and as a shock-absorber, protecting the inner
organs.