INTERGUMENTARY SYSTEM

Integumentary System
• One of the 11 organ systems.
Consists
• The skin
• Appendages (or accessory
structures) of the skin including:

– Sweat glands (sudoriferous glands)

– Sebaceous glands (oil glands)
– Hair
– Nails
 Integumentary system
• The skin (cutis, integument) and its derivatives
constitute the integumentary system.
• largest organ, Covers whole body and constitutes
15% to 20% of its total mass.

• It is an organ, because it consists of several kinds of

tissues that are structurally arranged to function
together.
 Integumentary system cont.
• The thickness of the skin varies with location of the
body

• Thickest on the parts of the body exposed to wear

and abrasion, such as the soles of the feet and
palms of the hand.
• Thinnest on the
• eyelids,
• external genitalia, and
• tympanic membrane (eardrum), where it is
approximately 0.5 mm thick
 General Functions of the
Integumentary System
• Protection from mechanical injury

• Physical protection of pathogen entry

• Chemical prevention of pathogen entry

• Sensation
• Thermoregulation
• Metabolic functions
• Looking good
 Protection
• It acts as a barrier that protects against
physical, chemical, and biologic agents in the
external environment (i.e., mechanical barrier,
permeability barrier, ultraviolet barrier).

• Resident lymphocytes and antigen-presenting

cells of skin
 Thermoregulatory
• A constant body temperature is maintained by
the skin's insulating components (eg, the fatty
layer and hair on the head) and its
mechanisms for accelerating heat loss (sweat
production and a dense superficial
microvasculature).
 Sensory
• It conveys sensory information about the
external environment to the nervous system.
• Many types of sensory receptors allow skin to
constantly monitor the environment and
various mechanoreceptors with specific
locations in skin are important for the body's
interactions with physical objects.
• Merkel cells
 Metabolic.
• Cells of skin synthesize vitamin D3, needed in
calcium metabolism and proper bone
formation.
• In sweat and the subcutaneous layer stores a
significant amount of energy in the form of
fat.
 Sexual signaling
• Many features of skin, such as pigmentation
and hair, are visual indicators of health
involved in attraction between the sexes in all
vertebrate species, including humans.
• The effects of sex pheromones produced by
the apocrine sweat glands and other glands of
skin are also important for this attraction.
 Types of Skin
• Categorized into; thick or thin
• Thick skin – palms, soles
• Thin skin – all part of body e.g. thinner -eyelid
• Two main layers –
– Epidermis
– Dermis
– Hypodermis
LAYERS OF THE SKIN
 Basic Skin
Structure
• The skin has 2 main
layers:
1. The superficial, avascular
epidermis (epi means
“above” and dermis means
“skin”) consisting of 4-5
layers of epithelial cells
resting upon a basement
membrane.
2. The deep, vascular dermis
consisting of fibrous
connective tissue. Contains
multiple blood vessels, and
the accessory appendages.
 FUNCTIONS OF THE SKIN
• Protects the body against injury, desiccation,
and infection
• Regulates body temperature
• Absorbs ultraviolet (UV) radiation, which is
necessary for synthesis of vitamin D
• Contains receptors for touch, temperature, and
pain stimuli from the external environment.
• Serves as an excretory organ via sebaceous,
sweat, and apocrine glands.
 EPIDERMIS
• It is the superficial layer of the skin.
• It develops from ectoderm

• It is classified as stratified squamous keratinized

epithelium.

• Avascular
 EPIDERMIS
• The epidermis has deep down growths called
epidermal ridges that interdigitate with
projections of the dermis (dermal ridges) to form
Prints
• Prints are produced on the surface of skin and
are visible on the finger/palm/foot.
• Prints/ridges are genetically determined and it is
unique to each individual (dermatoglyphics)
Notice the 4 layers of thin skin in both
the cartoon and the photomicrograph.
 LAYERS OF THE EPIDERMIS
• stratum basale
• stratum spinosum
• stratum granulosum
• stratum lucidum (absent in thin skin)
• stratum corneum
 Epidermal cell types:

1. Keratinocytes (structure)
2. Melanocytes (pigment)
3. Merkel cells (sensation)
4. Langerhans’ cells (phagocytes -
immune defense)
 Keratinocytes

• Most numerous epidermal cell – found in all layers

of the epidermis.
• Chief function is the production of keratin – a
tough fibrous protein that gives strength and
confers a lot of protective ability.
– Provides continuity, strength, and protection.
– Is the reason skin flakes off in sheets rather than
as individual cells.
• Ichthyosis
 Melanocytes
• Melanocyte produce melanosome
which is been converted to melanin by:
tyrosinase

• Melanin gives dark brown pigment

• Protect damaged by the ultraviolet

radiation from the sun.
•
 Merkel cells
• Merkel cells are present in small numbers in the
stratum basale, near areas of well vascularized,
richly innervated connective tissue.
• function as sensory mechanoreceptors.
 Langerhans cells
• Langerhans cells function as antigen-presenting cells
in immune responses to contact antigens
 DERMIS
• The dermis is the layer of the skin underlying the
epidermis
• it is divided into a
• superficial papillary layer –elastin connective
tissue
• a deeper reticular layer----collagen tissue

• The majority of the appendages of the skin are

contained within the dermis.
 PAPILLARY LAYER
• The papillary layer is composed of thin, loosely
arranged connective tissue, fine elastic fibers,
and capillary loops.
• Elastin gives the skin the ability to stretch and recoil.

• The dermal papillary layer is uneven and forms

dermal ridges (dermal papillae), which
interdigitate with the epidermal downgrowths
(epidermal ridges) forming the PRINTS
 Reticular layer
• located deep to papilary
• Dense connective with collagen fiber and elastic
fibres
• Contains:
• Arteries, veins, lymphatics and nerves
• Sweat glands
• Hair follicles and arrector pili muscles
• sebaceous glands
 SENSORY RECEPTORS IN DERMIS
• Pacinian corpuscles (pressure receptors)
• Krause end-bulbs ( cold receptor)
• Ruffinis (heat receptor)

• Located in the papillary layer are :

• Meissner corpuscles, (fine-touch receptors) it
may contain
 TYPE OF SKIN
• THICK & THIN
• Thick: It lines the palms and the soles.
• Thick skin lacks hair follicles, sebaceous glands, and
arrector pili muscles.
 Skin Types
1. Thick Skin
– Found on soles of feet and
palms of hands and
corresponding parts of
fingers and toes.
– Contains 5 epidermal
layers or strata (“sheets”):
• Stratum basale
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum
• Stratum corneum
• Thin has all epidermal layers except: lacks
• stratum lucidum
• Thin skin covers most of the body and contains:
• hair follicles,
• sebaceous glands, and
• arrector pili muscles.
• Apocrine sweat glands
 Skin Color
• Due to 3 pigments:
1. Melanin
2. Carotene
3. Hemoglobin
• Of these, only melanin is made in
the skin.
• Melanin:
– Its synthesis is catalyzed by an enzyme called tyrosinase.
Albinos lack this enzyme.
– Ranges in color from yellow to reddish brown to black.
– All people have the same # of melanocytes, individual
variations in skin color are due to how much and what
type of melanin is made.
• Carotene
– Yellow to orange pigment found in plant products such
as carrots.
– When large amounts are eaten, it can be deposited in
the stratum corneum of thick skin.
• Hemoglobin
– Pigmented protein that transports oxygen within the
blood.
– In Caucasians, the fair skin allows the crimson color of
oxygenated blood to make the skin have a somewhat
pinkish hue.
 CLINICAL CORELATION
• Psoriasis : appear almost anywhere on the body. It
is caused by an increase in mitotic activity of cells in
the basal layer of the epidermis

• Keloids: are swellings in the skin that result from

increased collagen formation in hyperplastic scar
tissue
 Skin cancer
• There are 3 types of skin cancers we will discuss:
– Basal cell carcinoma: most common 70% of skin
cancer
– Squamous cell carcinoma
– Malignant melanoma

• Warts (verrucae) a re common skin lesions ca

used by a virus
 VITILIGO

• An acquired destruction of melanocytes which

results in white patches on the skin.
 VITILIGO

• An acquired destruction of melanocytes which

results in white patches on the skin.

• Any age from infancy to old most common

third decade age.
• An autoimmune disorder associated
 ACNE VULGARIS

• Results from an over activity of the sebaceous

gland and a blockage in its duct.
 Appendages of
the Skin

1. Sebaceous glands
2. Sudoriferous glands
3. Ceruminous glands 1
4. Hair 4
5. Nails
2
 Glands of Skin- Sebaceous (Oil)
• Found at most parts of the body except palms
and soles
• Secretes oily glands which lubricates the body
• Open into the shaft in the dermis
• Secretory product is called Sebum
– keeps hair and skin soft & pliable
– Inhibits growth of bacteria & fungi (ringworm)
• Acne
– Bacterial inflammation of glands
– secretions stimulated by hormones at puberty
Sebaceous Gland
 Sebaceous Glands
• The duct empties into the neck of a hair
follicle.
• Absent from the palms and soles.
• They are most abundant on the face,
forehead, and scalp.
• holocrine glands release sebum (composed of
an oily secretion and degenerating epithelial
cells).
• Sebum has a number of functions, such as:
• maintaining the skin's barrier to aqueous
fluids,
• Nutrient for hair
• shielding skin from microorganisms
• Antimicroial
• maintaining the suppleness of skin and the
luster of hair.
 Sweat/Sudoriferous
Glands
• Eccrine/Merocrine sweat gland/Non-
Smelly
– Distributed all over the body (sweaty palms, back,
chest)
– True sweat, Non-smelly
– Regulate body temperature with perspiration
• Apocrine Sweat gland/Smelly
– Armpits (axillary) and pubic regions (anus,
external genitalia, groin)
– Smelly sweat
– Eyelashes (Glands of Moll)
Sudoriferous Glands
• Sweat glands.
• Distributed over the
entire body except the
nipples and portions of
the external genitalia.
• Over 2.5 million per
person.
• 2 types:
1. Merocrine/ eccrine
sweat glands
2. Apocrine sweat glands
Sweat/Sudoriferous Glands
 Sweat Glands
• Eccrine/merocrine sweat glands
• Present in skin throughout most of the body but not
in the lips and certain regions of the external
genitalia.
• Eccrine sweat glands function in controlling body
temperature, conserving electrolytes, and excreting
urea and lactic acid.
• Hyperhidrosis is a disorder of excessive sweating ca
used by overperspiration from secretion by eccrine
sweat glands in the skin.
 Apocrine sweat glands
• located in various areas of the body (e.g.,
axilla, areola of the nipple, perianal region),
pubic, and anal regions of the body.
• These glands do not begin to function until
puberty and are responsive to hormonal
influences.
• Empty content into hair follicle (odor)
 Specialised Apocrine glands
• ceruminous (wax) glands of the external
auditory canal
• Malbomian
• pheromone
 Specialized Skin Glands
• Ceruminous glands
– Modified sweat glands produce waxy secretion in
ear canal
– Cerumin contains secretions of oil and wax
glands
– Helps form barrier for entrance of foreign bodies
– Impacted cerumen may reduce hearing
• Mammary glands are specialized
sudoriferous glands that have developed to
secrete colostrum and milk
Ceruminous Glands

• Modified apocrine glands found in the inner lining

of the external ear canal.
• Secrete a sticky waxy substance called cerumen
(earwax). It combines with sebum and dead
epidermal cells to form a bitter compound that
offers a barrier to entry of the ear.
 Sensory endings
• The skin performs its functions due to the presence of
nerve receptors embedded in it
• Touch, pressure
– Meissner’s corpuscles: light touch
– Pacinian corpuscles: pressure
– Free nerve endings: light touch, temperature, pain
– Organs of Ruffini: pressure
– Bulbs of Krause: light touch
• Pain receptors
– sense tissue damages
• Temperature receptors
– sense heat and cold
Sensory Nerve Endings of Skin
 Hair and Hair Follicles
• Hair is a flexible strand made of
highly keratinized dead cells.
• The keratin in both hair and nails
is hard keratin, a stiffer, more
compact version of the soft
keratin that dominates the
epidermis. It is tougher and its
cells do not individually flake off.
• The hair is made by the living hair
follicle.
Hair and Hair Follicle
 Hair and Hair
Follicles
• Wrapped around the bulb of the
follicle is a network of sensory nerve
endings known as the hair root
plexus. Allow the hairs to serve a
sensory function.
• Attached to each hair is a bundle of
smooth muscle known as an
arrector pili muscle. In times of
fright or cold, these muscles contract
and cause the hair to stand on end –
and produces goose bumps.
 Arrector Pilli Muscle
• Smooth muscle in dermis
• Contracts with cold or fear
• Contraction of the arrector muscles of hairs
erects the hairs, causing goose bumps
• Hair follicles are slanted to one side, with
sebaceous glands on the side the hair
• Contraction of the arrector muscles causes the
hairs to stand up straighter, thereby compressing
the sebaceous glands and helping them secrete
their oily product onto the skin surface
• There are three types of human hairs:
• lanugo: present prenatally and vanish shortly after
birth (fine longish)
• vellus hairs and terminal hairs: present postnally
• Vellus hairs are present throughout the individual's
life. They are almost invisible, but when
viewed in sunlight at an angle, for instance, on a
person's eyelids (on the skin of the eyelids)
• Terminal hairs are the coarse, long, highly
keratinized, dark hairs.
• These are present on the head, eyebrows,
eyelashes, pubic hairs, etc. Most of the
primate body is covered by terminal hair.
• Interestingly, keratinocytes (stem cells) are
present even in bald individuals, but the
signalling molecules that induce them to form
new hair are absent.
• Matrix of hair root form medulla: Melanocytes
• Age affect tyrosinase synthesis by melanocytes of
the hair follicles diminishes and results in the
absence of melanin production, and hair loses its
color and turns gray.
 Description of the skin
appendages( nails)
• Nails are located on the distal phalanx of each
finger and toe
• Nails are hard keratinized plates that rest on
the nail bed composed of the epidermis and
underlying dermis of the skin

• Anonychia(failure of nail to from)

• Nails grow as the result of mitoses of cells in
the matrix of the nail root.
• Fingernails grow no more than 0.5 mm per
week, and toenails grow a bit slower;
interestingly, growth is faster in the summer
than in any other time of the year.
 MAMMARY GLAND
• The mammary gland is a modified sweat gland at
the pectoral region.
• Found in both sexes. However, it remains
rudimentary in male but becomes well developed in
female at puberty.
• On rare occasions the breasts of male become
enlarged, this condition is called gynecomastia.
• In female, it forms an accessory sex organ and
provides milk to the new born
• Shape: Hemispherical bulge.
 STRUCTURE OF BREAST
• Skin (nipple, aerola)
• Stroma (connectitve tissue, fat)
fibrous
suspensory ligament of cooper
• Parrenchyma (glands)
15- 20 lobes
lactiferous duct
lactiferous sinus
• Breast develop from ectodermal thickening
(milk line/ridge of schult)
• Ectodermal thickening to form nipple
• Stroma develop from mesoderm
 SKIN OF THE BREAST
• Skin the following features:
• Nipple: It is a conical projection below the
center of the breast, usually at the level of the
4th intercostal space.
• It contains smooth muscle fibers which can
make the nipple stiff and erect or flatten it.
• Sensitive to touch: richly innervated by
sensory nerve endings
• Areola: It is the circular area of pigmented skin
surrounding the base of the nipple.
• It contains large number of modified sebaceous
glands produce oily secretion which lubricates the
nipple and areola, and thus prevents them from
drying and cracking.
• The color of the areola and nipple varies with the
complexion of the woman. During pregnancy the
areola becomes darker and enlarged.
• Montgomery’s tubercles (enlarged glands}
 Subcutaneous Tissue
• A.k.a. the hypodermis or the
superficial fascia.
• Deep to the dermis.
• Consists of primarily adipose
tissue plus some areolar
connective tissue.
• Stores energy, provides
insulation and padding.
• Anchors the skin to
underlying structures,
especially muscles.
• Different distribution
between the sexes.
 ACNE VULGARIS

• A chronic disorder of the pilosebaceous

apparatus which result in greasiness and a
polymorphic eruption on the face.
 AETIOLOGY

• Results from an over activity of the

sebaceous gland and a blockage in its duct.
• The gland is under the control of
androgens.
• Does not secrete until puberty.
• Gland occur in association with hair
follicles.
• Sebum is increase in Acne.
• Pustule of acne represent a collection of
sebum and they are quite sterile.
 PSORIASIS

• A common erythematosquamous disorder of

unknown aetiology.
• A chronic benign hyper proliferative condition
of the skin.
• Often inherited.
• Sometimes associated with disorders of joints
and nails.
 Tinea (Ring worm)
• Caused by a superficial fungus which
colonizes keratin- hair, nails and
outermost layer of the skin
• Host factors are important
• Impaired cell-mediated immunity
predisposes to these infections
• Children are susceptible to scalp
ringworm whereas adults are not.
 Tinea (Ring worm)

• Males have a higher incidence of Tinea

• Tinea infections often result from
damage to the
• Occlusion increases the local
temperature and hydration of the skin
leading to impaired barrier function
• Tinea cruris and pedis are common.
• There are various types (variants)
 TINEA CAPITIS

• One or more patches of Alopecia.

• Scaling with minimal inflammation of scalp.
• Starts as a small red papuce which sumlonus
hair shape and spread centrifugally.
• Well demarcated patches.