Download THE INTEGUMENTARY SYSTEM

THE INTEGUMENTARY
SYSTEM
The Integumentary
system
• Skin is the largest organ in the body
• The Integumentary system consist of:
1. the skin
2. its derivatives. These include hair, nails,
and several types of glands.
FUNCTIONS
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Protection
regulation of body temperature
excretion of waste materials
synthesis of vitamin D
reception of various stimuli
perceived as pain, pressure and
temperature.
Skin
• LAYERS OF THE SKIN:
1. epidermis
2. Dermis
3. hypodermis.
Epidermis
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the outer layer of the skin
made of stratified squamous epithelium
no blood supply
Epidermis contains 4-5 strata.
stratum cornium
Stratum lucidium
Stratum granulosum
Stratum spinosum
Stratum basale,.
5 LAYERS OF EPIDERMIS
• Stratum cornium is the outer, dead, flat, Keratinized and
thicker layer.
• Stratum lucidium is next to stratum cornium. It consists
of flat, translucent layers of cells. This stratum found in
thick skin only.
• Stratum granulosum lies just below stratum lucidium.
The cells in this layer are in the process of keratinization
• Stratum spinosum: next down to stratum granulosum.
The cells in this stratum have a poly-hydral shape and
they are in the process of protein synthesis.
• Stratum basale rests on the basement membrane, and it
is the last layer of epidermis next to stratum spinosum.
LAYERS OF DERMIS-1
• Dermis is also referred to as the true
skin
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Papillary layer is next to stratum basale
of the epidermis.
contains loose connective tissue with in
the bundles of collagenous fibers
loose capillaries that nourish the
epidermis.
In some areas papillary layer have special
nerve endings that serve as touch
receptors .
LAYERS OF DERMIS-2
2-Reticular layer:
• next to papillary layer.
• made of dense connective tissue
with course of collagenous fiber
• bundles that crisscross to form a
storma of elastic network.
• many blood and lymphatic vessels,
nerves, fat cell, sebaceous (oil)
glands and hair roots are embedded.
• Receptors of deep pressure are
distributed through out the dermis.
Hypoderms
• found beneath the dermis.
• subcutaneous layer (under the skin).
• Hypodermis is composed of loose,
fibrous connective tissue
• richly supplied with lymphatic and
blood vessels and nerves
• much thicker than dermis. With in it
coils of ducts of sweat glands, and
the base of hair follicles.
Functions of Skin
• 1. Protection: against harmful microorganisms,
foreign material and it prevents excessive loss of
body fluid.
• 2. Temperature regulation: with the sweat, heat
leaves the body.
• 3. Excretion: Small amount of waste products from
the body such as urea.
• 4. Synthesis: By the action of UV. Vitamin D is
synthesized in the skin. Vitamin D is necessary for
absorption calcium from intestine.
• 5. Sensory reception: it contains sensory receptors
of heat, cold, touch, pressure, and pain.
Color of the skin
determined by 3 factors :1. presence of melanin- a dark pigment produced by
specialized cell called melanocyte.
2. The accumulation of yellow pigment carotene.
3. The color of blood reflected through the epidermis.
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The main function of melanin is to screen out
excessive ultraviolet rays.
• All races have some melanin in their skins although
the darker races have slightly more melanocyte.
• The person who is genetically unable to produce
any melanin is an albino.
Glands of the Skin
• sweat glands:• Types: Eccrine and Apocrine glands .
Eccrine glands are small, simple coiled tubular
• glands distributed over nearly the entire body
• absent over nail beds, margins of lips of vulva, tips
of male genital organ.
• numerous over the palms and soles
• sweat they secret is colorless, aqueous fluid
containing neutral fats, albumin, urea, lactic acid
and sodium chloride
• excretion helps body temperature to be regulated.
GLANDS OF SKIN
Apocrine glands
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Odiferous
found at the armpits, in the dark region around nipples,
the outer lips of the vulva, and the anal and genital
regions
larger and deeply situated than eccrine sweat glands
apocrine sweat gland becomes active at puberty
respond to stress
The female breasts are apocrine glands that have
become adapted to secret and release milk instead of
sweat.
The glands in the outer ear canal are also apocrine skin
glands.
Sebaceous (Oil) glands
• Sebaceous glands are simple branched
alveolar glands found in the dermis
• main functions are lubrication and
protection
• connected to hair follicles
• secret oily secretion called sebum. It is a
semi fluid substance composed of entirely
lipids
• functions as a permeability barrier, skin
softening and a protective agent against
bacteria and fungi
• found all over the body
Hair
• Hair is an appendage of the skin
• composed of Keratinized
threads of cells
• develops from the epidermis
• It covers the entire body except
the palms, soles, lips, tip of
male genital organ, inner lips of
vulva and nipples.
Function
• - Insulation against cold in scalp
• - Against glare in eye brows
• - Screen against foreign
particles (eye lashes)
• - In the nostrils trap dust
particles in the inhaled air
• - Protect openings from foreign
particles.
Structure of Hair
• Hair has two parts, the shaft the part above skin
and the root embedded in the skin.
• The lower portion of the root, located in the
hypodermis enlarges to form the bulbs. The bulb
forms a papilla of blood rich connective tissue
• Part of the hair follicle is attached with the bundle
of smooth muscle called arrecter pili muscles.
• When it contracts it pulls the follicles and its hair to
an erect position.
• Hair grows and when it finishes its growth sheds.
The growth rate of hair depends on its position. The
fastest growth rate occurs over the scalp of women
aged 16 to 24 years.
Nail
• Nails, like hair are modifications of the epidermis. They
are made of hard keratin. Nails are composed of flat,
cornified plates on the dorsal surface of the distal
segment of the fingers and toe. The proximal part of nail
is lunula, which is white in its color because of the
capillaries underneath are covered by thick epithelium.
Nail has body and root. The body is the exposed part and
the root is hidden under the skin. The nail ends with a
free edge that overhangs the tip of the fingers. Epithelial
layer covering underneath of the fore-hang nail is
hyponychyem. The nail rests on an epithelial layer of skin
called nail bed. The thicker layer of skin beneath the nail
root is the matrix, where new cells are generated. Nail
grows 0.5 m.m a week. Thin layers of epidermis called
eponychium originally cover the growing nail. Our nail
protects our fingers and toes. It also allows picking up
and grasping objects as well we use them to scratch.
Effects of Aging on the
Integumentary System
• Blood flow to the skin is
reduced, the skin becomes
thinner, and elasticity is lost.
• Sweat and sebaceous glands
are less active, and the number
of melanocytes decreases.