Anatomy of integumentary systems for.ppt

Consists of skin and its
appendages including:
Sweat glands (sudoriferous
glands)
Sebaceous (oil) glands
Tarsal(Moll’s) glands
Hair
Nails
Skin is the largest organ
in the body
5/18/2024
2
The Integumentary system

Functions
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3
 Protection
 Sensation
 Thermoregulation
 Metabolic functions
 Looking good
 Excretion and absorption
 Synthesis of vitamin D.

Skin Types
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4
1. Thick Skin
 Found on sole & palm
 Contains 5 epidermal
layers or strata
(“sheets”):
 Stratum basale
 Stratum spinosum
 Stratum granulosum
 Stratum lucidum
 Stratum corneum

…cnt
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2. Thin skin
 Found everywhere else on the
body.
 Contains only 4 layers. (lacks a
stratum lucidum).
 The remaining 4 layers are thinner
than those of thick skin.

Thick skin
Thin skin
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Skin Layers
 Has 2 main layers:
1.Epidermis
• superficial
• avascular
• consists 4-5 layers
2.Dermis
 deep
 vascular consisting of
fibrous connective tissue.
 Contains multiple blood
vessels, and the
accessory appendages. 5/18/2024
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Epidermis
Dermis

The Epidermis
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10
 Keratinized stratified
squamous epithelium.
 Consists of 4 distinct cell types
arranged in 4 or 5 distinct
layers.
 Epidermal cell types:
1. Keratinocytes (structure)
2. Melanocytes (pigment)
3. Merkel cells (sensation)
4. Langerhans’ cells
(phagocytes - immune
defense)
blak arrow indicates the
epidermis of thick skin

Keratinocytes
 Most numerous-90%
 Found in all layers
 Produce keratin – a tough
fibrous protein that gives
strength and confers a lot of
protective ability.
11
Almost all of the epidermal cells in this slide
are keratinocytes

…Keratinocytes
 New cells are
continuously made in
the deepest layer
pushing the older
cells up.
 As the keratinocytes
move farther from
the deepest layer,
they make the keratin
that eventually
dominates their cell
contents.
5/18/2024
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When they have reached the upper layer,
they are nothing more than scale-like bags
of keratin.

Melanocytes-8%
 Spider-shaped
 synthesize the protein
pigment melanin.
 Found in the deepest layer
of the epidermis.
 Melanin is made and then
packaged into membrane-
bound granules called
melanosomes.
 Granules are transferred to
the keratinocytes in the 2
deepest layers of the
epidermis.
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Arrows indicate 2
melanocytes.

…cnt
 Melanin granules
accumulate on the
“sunny side” of the
nucleus of the
keratinocytes.
 Melanin granules protect
the DNA within the
nucleus from being
damaged by the UV
radiation
5/18/2024
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…cnt
• Merkel cells
• Sensory cells
• They send their free nerve endings into the
epidermis, which are very sensitive to gentle
touch.
• Langerhans cells
• Fixed macrophages
• Participate in immune responses mounted
against microbes that invade the skin.
• Langerhans cells help other cells of the
immune system recognize an antigen.
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Stratum Basale
 Deepest epidermal layer. Firmly attached to the underlying
dermis.
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 Single row of cuboidal
keratinocytes
 Interposed with
melanocytes & Merkel
cells.
 Cells in this layer are
mitotically active

Stratum Spinosum
 2nd deepest layer.
 Consists of 8-10
layers of cells.
 Cells of the lower
layers can still be
mitotic.
 As cells get pushed
upward, they begin to
flatten and begin to
make the precursors
of keratin.
 Langerhan cells and
Melanocytes are often 5/18/2024
18

Stratum Granulosum
 3-5 cell layers thick.
 Cell morphology begins to
change dramatically
 cells continue to flatten and their
nuclei and organelles
disintegrate.
 Accumulate granules
containing a precursor of
keratin and granules containing
a waterproofing agent.
5/18/2024
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Stratum Lucidum
Flat, dead keratinocytes
appears clear in the
light microscope
because it lacks nuclei
and organelles which
typically stain well.
 Present only in thick skin
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Stratum Corneum
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 Outermost stratum.
 20 – 30 layers of flat
(squamous), highly
keratinized, dead cells.

Dermis
 Strong, flexible fibrous
connective tissue.
 Cells: fibroblasts,
macrophages, mast cells,
WBCs
 Fiber types: collagen,
elastic, reticular
 Rich supply of nerves and
vessels
 Critical role in temperature
regulation (the vessels)
 Divided into -papillary &
-reticular dermis.
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dermal papillae

Papillary Dermis
Makes upper 1/5 of the dermis
Consists of loose (areolar) CT.
Provides an arena for immune cells to fight
invaders.
Consists of:
 Capillaries
 Nerve axon
 Meissner corpuscles, nerve endings that are
sensitive to touch.
 Free nerve endings that are associated with
sensations of warmth, coolness, pain, tickling, &
5/18/2024
25

Reticular dermis
Forms lower 4/5
 Consists of dense
irregular CT
Attached to
hypodermis
Consists of:
 Hair follicles
 Sweat glands
 Sebaceous
glands
 Adipose cells, 5/18/2024
26
short arrow indicates the papillary dermis and
long arrow indicates the reticular dermis

Vessels in the skin
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Arteries form 2 plexuses.
1.Sub- papillary plexus
- below the dermal papillae, supplies the more
superficial dermal structures
2.Dermal plexus (coetaneous plexus)
-at the junction of dermis and hypodermis
-It nourishes the hypodermis and the structures
located within the deeper portions of the dermis
Veins form the three plexuses – 2 in same
position as for arterial and another in the middle
of the dermis.

Function of dermal blood
vessels
 Nourish the dermis and overlying epidermis
 Temperature regulation(these vessels are so
extensive that they can hold 5% of all blood in
the body.
 When internal organs need more blood or more
heat, nerves stimulate the dermal vessels to
constrict, shunting more blood into the general
circulation and making it available to the internal
organs.
 By contrast, on hot days the dermal vessels
engorge with warm blood, cooling the body by
radiating heat away from it). 5/18/2024
29

Sensory receptors in skin
5/18/2024
30
 Free nerve ending
 Merkel's cells noncapsulated
 Hair follicle receptors
 Pacinian corpuscles
 Ruffini ending capsulated
 Meissener’s corpuscles

Hypodermis/Subcutaneous tissue/superficial fascia
 Is not part of skin
 Consists of adipose + some
loose CT.
 Stores energy, provides
insulation(prevent heat loss)
and padding.
 Anchors the skin to underlying
structures, especially muscles.
 Different distribution between
the sexes.

Skin Color
 Is due to :
1. Melanin
2. Carotene
3. Hemoglobin
 Of these, only melanin is made in the
skin.
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1. Melanin:
 Polymer of tyrosine amino acids. 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.
– Freckles and moles are local accumulations of melanin.

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2. Carotene
Yellow to orange pigment found
in plant products such as carrots.
When large amounts are eaten accumulates in the;
 Stratum corneum
Fatty areas of the dermis and
Subcutaneous layer
3. Hemoglobin
Pigmented protein that transports oxygen within the blood.
make the skin have a somewhat pinkish.
…Skin color

Albinism ????
• Normal number of melanocytes in the epidermis
• But lack of the enzyme tyrosinase that converts the
amino acid tyrosine to melanin
• It is a hereditary condition
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Appendages of the Skin
1. Hair
2. Nails
3. Skin glands
a. Sebaceous glands
b. Sweat/ sudoriferous glands
1.Eccrine
2.Apocrine
3.Ceruminous
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1
2
4 3

Hair
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.
5/18/2024
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Parts & regions of Hair
Consists of 2 parts;
shaft & root
Has 3 concentric regions:
 Medulla  the innermost region
consisting of large cells and air
spaces.
 Cortex  surrounds the medulla
and consists of flattened
keratinized cells
 Cuticle  outer layer of flat
keratinized cells that overlap
their free edges pointing upward.
5/18/2024
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Hair Follicle
Surrounds hair root.
Has two layers: which is made up of epidermal
cell
1.External and
2.Internal root sheaths
Externally Surrounded by a connective tissue
sheath.
5/18/2024

…cnt
At the base of the hair follicle is a single layer of
mitotic cells derived from the stratum basale.
All the cells of the hair are derived from the hair
matrix.
Beneath the hair matrix is an obvious dermal
papilla called the hair papilla.
 It contains the blood vessels that nourish the
matrix and the cells of the hair follicle.
5/18/2024
42

Onion-shaped enlarged structure at the base of each hair
follicle.
Bulb contains:
1.Papilla of the hair a nipple-shaped indentation
contains many blood vessels provides nourishment for the
growing hair
2.Hairmatrix -single layer of mitotic cells(Keratinocytes)
derived from the stratum basale & produces new hairs by
cell division when older hairs are shed.
43
Hair Bulb

Hair root plexus
 Are network of sensory nerve endings
wrapped around the bulb of the
follicle
 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.
5/18/2024
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Types of hair
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3 types;
1.Lanugo -is fine, unpigmented hair
appears on the fetus in the last 3 months of development.
2.Vellus- at birth, most of Lanugo hair is replaced by similar
fine, unpigmented hair called vellus.
3.Terminal hair- is longer, coarser, and pigmented.
occurs on the scalp, eyebrow, and eyelashes, axillary , pubic
regions, on the face of males (to from the beard), and to
varying degrees on the trunk and limbs.

Hair Growth Stages
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 Hair growth - averages( 2 mm/week)
 The hair growth cycle consists of a growing stage and a resting
stage.
 Growth stage- anagen and catagen
lasts for 2 to 6 years
matrix cells at base of hair root producing length
 Resting stage- telogen
Lasts for 3 months
Matrix cells inactive & follicle atrophies
Old hair falls out as growth stage begins again
 Normal hair loss is 70 to 100 hairs per day

Hair Color
 Is due to pigment granules in the cells of the cortex.
 Melanin production decreases with age
 Decreased production results in gray hair
 Lack of melanin and the presence of air bubbles in the
hair shaft results in white hair
 Hair Color is influenced by:
 Genetics
 Hormones
 Environmental factors
 Age Gray hair
48

…Hair color
5/18/2024
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Brown and black hair are colored by a form of
melanin called Eumelanin.
Blond hair has a scanty amount of eumelanin
but a moderate amount of sulfur-containing
pigments called Pheomelanins.
Red has a slight amount of eumelanin but an
abundance of pheomelanins. White hair results
from a lack of pigments in the cortex and a
presence of air in the medulla.

Nails
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 Composed of a compressed layer of stratum corneum cells
 Hardness derived from dense keratin deposits
 Parts:
• Body
• Free border (tip of the nail)
• Nail bed (what the nail rests on (stratus spinosum of the
dermis)
• Hyponychium = epithelium of nail bed(stratum corneum of
the nail)
• Eponychium /cuticle
 Cuticle is a fold of stratum corneum on the proximal end of
nail

…cnt
5/18/2024
51
Nail body
visible portion pink due to
underlying capillaries
free edge appears white
Nail root
buried under skin layers
Lunula is white due to
thickened stratum basale-
nail growth occurs here

Sebaceous Glands
 Simple alveolar glands found
everywhere except palms of the
hands and soles of the feet.
 Secrete an oily, lipid-rich
secretion called sebum.
 Sebum is or occasion typically
secreted into a hair follicle -
onto the body surface.
 Sebum softens and lubricates
the skin.
 It also decreases the skin’s
permeability to water and is
quite bactericidal.
5/18/2024
54

The sebaceous gland is indicated by the arrow. Note how its
duct is unbranched and how it empties into a hair follicle.
5/18/2024
55

Sudoriferous Glands/ Sweat glands
 Distributed over the entire
body except the nipples
and portions of the external
genitalia.
 Over 2.5 million per person.
 Three types:
1. Merocrine/Eccrine
sweat glands
2. Apocrine sweat glands
3. Modified apocrine
glands  Ceruminous
and Mammary glands
5/18/2024
56

Merocrine Sweat
Glands
57
 More numerous than apocrine sweat
glands.
 Especially prominent on the palms,
soles, and forehead.
 Simple, coiled, tubular glands.
 Duct empties into a funnel-shaped
pore at the skin surface.
 Major function is to cool the body -
thermoregulation.

 Merocrine sweat is a dilute
watery solution of some salts
(including NaCL), vitamin C,
antibodies, small amounts of
nitrogenous wastes (urea, uric
acid, and ammonia), and lactic
acid.
 PH of sweat is 4-6 creating a
film on the body known as the
acid mantle.
 Such an acidic environment is
bacteriostatic – prevents
bacterial reproduction and
growth.
5/18/2024
58

Apocrine Sweat
Glands
5/18/2024
59
Found primarily in the axillary,
pubic, and anal regions of the body.
 Also found in the facial region in men
only.
Larger than merocrine sweat glands.
Ducts empty into hair follicles.
Apocrine sweat is thicker than
merocrine sweat since it contains
more lipids and proteins.
When it’s degraded by epidermal
bacteria, foul odors can be produced.

Apocrine Sweat Glands
5/18/2024
60
 Become active at puberty.
 Secrete sweat during times of pain, stress, and sexual
activity.
 May (??) have a possible pheromone-like function.
 Play no role in thermoregulation.
Remember: Glands are derivatives of epithelial tissue. So even
though many reside in the dermis, they are not made from
connective tissue.

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.
5/18/2024
61

Disorders of the Integumentary System
5/18/2024
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Acne vulgaris
 Caused by increased secretion of oil related to increased
hormones during puberty
Albinism
Inherited disorder in which melanin is not produced
Alopecia
Baldness
Athlete’s foot
Contagious fungal infection of the foot
Wart
 Papule caused by a viral infection(HPV)

Albenism
no melanin
5/18/2024
63

Vitiligo
Condition that causes loss of pigment
in the skin
5/18/2024
64

Chloasma
is a patterned pigmentation
of the face
occurring in women during
pregnancy or when taking
oral contraceptives.
The areas of increased
pigmentation are well defined,
symmetrical and their edges
are often scalloped (the mask
of pregnancy
placenta may secrete
hormones that stimulate
melanocytes
Exacerbated by sun light 5/18/2024
65

…cnt
5/18/2024
66
Cellulitis
Bacterial infection of the dermis and subcutaneous layer of
the skin
Cleft lip
Upper lip has a cleft where the nasal palate doesn’t meet
properly
Contact dermatitis
Allergic reaction that may occur after initial contact or as an
acquired response

…cnt
5/18/2024
67
Dandruff
White flakes of dead skin cells from the scalp
 Decubitus ulcers
Sores or areas of inflammation that occur over bony
prominences of the body
Eczema
Group of disorders caused by allergic or irritant reactions
characterized by redness, itching…
Fungal skin infections
Skin infections that live on dead outer surface or epidermis

…cnt
5/18/2024
68
Furuncle
Boil, or bacterial infection of a hair follicle
 Hirsutism
Abnormal amount of hair growth in unusual places
Impetigo
Very contagious bacterial skin infection that occurs most
often in children
Kaposi’s sarcoma
Form of cancer that originates in blood vessels and spreads
to skin

Hirsutism
Abnormal amount
of hair growth in
unusual places.
5/18/2024
69

5/18/2024
70
Lupus
 Benign dermatitis or chronic systemic disorder
Psoriasis
 Chronic skin disorder in which too many epidermal cells are produced
Rashes
 May result from viral infection, especially in children
Scleroderma
 Rare autoimmune disorder that affects blood vessels and connective
tissues of the skin
…cnt

Skin Cancer
 Because of its role as our external covering, the skin takes a
tremendous amount of abuse.
 One serious disorder that can result is skin cancer.
 Cancer can be thought of as uncontrolled cell division and growth.
 There are 3 major types of skin cancers
 Basal cell carcinoma
 Squamous cell carcinoma
 Malignant melanoma
5/18/2024
71
An abnormal cell develops
From abnormal cells, a
cancerous cell develops
Cancerous cells spread,
forming a tumor

…cnt
Basal cell carcinoma
Most common (70% of skin
cancers)
Least vicious/dangerous/
Usually cured via surgical
removal
Consists of uncontrolled growth
of cells of the stratum basale.
They’ll proliferate and invade the
dermis and hypodermis.
Often occurs on sun-exposed
areas of face and neck
5/18/2024
72

…Cnt
Squamous cell carcinoma
Arises from keratinocytes of
stratum spinosum.
25% of cases.
Good prognosis if caught and
treated early (surgical excision
or radiation).
Can be fatal if it metastasizes
to the lymph nodes.
5/18/2024
73

…Cnt
5/18/2024
74
Malignant melanoma
Least common and most dangerous.
Cancer of melanocytes.
Often arises from a pre-existing mole.
Follow the ABCD rule for early
detection:
Asymmetry (2 sides do not match)
Border irregularity
Color (multiple)
Diameter (>6mm is bad!)

First-degree
Only the epidermis is
damaged
Symptoms include
localized
redness,
swelling, and
pain
5/18/2024
76

Second-degree
Epidermis and upper
regions of dermis damaged
Symptoms mimic first
degree burns, but
blisters also appear
5/18/2024
77

Third-degree
Involve entire thickness of
the skin, and may extend into
the subcutaneous tissue
Exposes the victim to fluid
loss & infection
 Burned area appears gray-white,
cherry red, or black, and there is no
initial edema nor pain (since nerve
endings are destroyed)
5/18/2024
78

Critical burns
5/18/2024
79
 Over 10% of the body has
third-degree burns
 25 % of the body has
second-degree burns
 Third-degree burns on face,
hands, or feet
 When more than 20% of
the body has been burned,
the injury is often fatal.
Estimate by “rule of 9’s”

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