The Integumentary System
Chapter 5
Integumentary System Includes:
Skin (cutaneous membrane)
 Subcutaneous tissue below the skin
 Accessory Structures
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Sweat glands
Sebaceous or oil glands
Hair
Nails
Layers Of The Skin
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Epidermis – outer
◦ composed of stratified
squamous epithelium
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Dermis – inner
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anchored to a
subcutaneous layer
• Hypodermis
• subcutaneous fat
(adipose) layer –
• energy storage
Epidermis
Composed of stratified squamous
epithelium
• Avascular- as it has no blood supply of its
own
• Oxygen and nutrients diffuse from the
underlying dermis
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Click here to copy the picture
“skin, thick trichrome”
And paste it here.
Click here to copy the picture
“skin, thin H&E”
And paste it here.
First Layer of the Epidermis
Stratum Basale
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Deepest layer of the epidermis (closest to the dermis).
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Consists of a single layer of columnar or cuboidal cells
Renewal - takes about 3 to 4 weeks
Cells here undergo keratinization
• keratin- a tough protein, is deposited within the cell.
• keratin hardens and flattens the cells as they move outward and it
waterproofs the skin.
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Epidermal Layers
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Stratum spinosum
• Consists of spiny prickle cells that interlock
to support the skin.
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Stratum granulosum
• This thin middle layer, initiates
keratinization (production of keratin).
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Stratum lucidum
• This thick layer appears only in frequently
used areas such as palms of the hands and
soles of the feet.
Final Epithelial Layer
Stratum Corneum
• Outermost layer
• Thick with rows of dead cells.
• These cells contain soft keratin, which keeps
the skin elastic and protects underlying cells
from drying out.
• Act as barrier against microbe invasion.
Dermis- Called "true skin, " is the layer
beneath the epidermis. Its major components
are:
• collagen (a protein that adds
strength)
• reticular fibers (thin protein fibers
that add support)
• elastic fibers (a protein that adds
flexibility)
Click here to copy and paste the picture
“skin, thick van Gieson elastin”
Skin Color
Skin color results from the presence of :
• Melanin- keeps excessive ultraviolet rays from burning the skin.
Exposure to sunlight causes the skin to produce more melanin,
causing suntan, a temporary change in skin color. Melanin-rich
cells continually move toward the surface, where they are
sloughed.
• Carotene -yellow to orange pigment usually hidden by the
effects of melanin. underlying blood reflected through skin.
• Pigmentation is not just under the control of light. Hormones
produced by the pituitary and the adrenal glands also affect
pigmentation. Diseases of these two endocrine organs often
result in changes of pigmentation of the skin.
Melanin
Click here to copy and paste a picture of
The integument showing
melanocytes stained blue
Malfunctioning Melanocytes
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Albinism – melanocytes completely fail to
secrete melanin. Hair, skin, and iris are white.
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Freckles and moles are formed when melanin
becomes concentrated in local areas.
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Malignant melanoma – a cancerous change in
a mole that may metastasize (spread) rapidly
and is most difficult to treat. Exposure to
sunlight increases risk.
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Vitiligo – loss of pigment in certain areas of the
skin producing white patches.
Vitiligo
Other Pigments in Skin
Pinkish color – seen in fair-skinned persons
because the vascular dermis is visible.
• Cyanosis – blue look to skin due to poorly
oxygenated blood
• Blushing – caused by dilation of blood vessels
• Pale by fright – caused by restriction of vessels
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Response to Disease
Jaundice – when bilirubin is deposited in skin
because a diseased liver is unable to excrete this
pigment
• Skin may appear bronzed due to the deposit of
excess melanin when a person’s adrenal gland is
functioning poorly.
• A bruise or contusion indicates that blood has
escaped from the blood vessels and has clotted under
the skin.
• Over eating carotene-rich vegetables such as
carrots may cause skin to have a yellow tint.
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Accessory Structures of the Skin
◦ Hair -Most of the skin is haired although the
hair in most areas is short, fine and only lightly
pigmented.
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Truly hairless -the palms of hands
soles of feet
sides of fingers and toes
parts of the external genitalia.
Accessory Structures of the Skin
The free part of each hair is called the shaft.
The root of each hair is anchored in a tubular invagination
of the epidermis, the hair follicle, extends down into the
dermis.
• The hair that you groom daily is actually dead keratinized
cells.
• Each has an associated bundle of smooth muscle, the
arrector pili muscle. causes your hair stand up on its
end.
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Accessory Structures of the Skin
Hair Color and Texture
• Hair color is determined by the amount and type
of melanin present.
• Melanocytes become less active with age= Gray
hair
• Red hair results from a modified type of melanin
that contains iron.
• The shape of the hair shaft determines texture.
Alopecia is the term for hair loss.
Accessory Structures of the Skin
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Nails
◦ Plates of stratified squamous epithelial cells
with hard keratin
◦ Protect distal ends of phalanges
◦ Nail growth occurs in the lunula
◦ Athlete's foot is a fungal infection that develops
in the moist areas between your toes and
sometimes on other parts of your foot.
Exocrine Glands
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Sweat glands or sudoriferous glands - simple coiled tubular glands.,
divided into two principal types:
eccrine and apocrine.
Apocrine glands - found mainly in the skin of the armpits, anogenital
areas and of the areola of the breasts.
• They start secreting at puberty.
Eccrine glands are the most common.
• Their secretory portion can be located in the dermis or in the hypodermis.
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Produce sweat, a watery mixture of salts, antibodies and metabolic wastes.
• Sweat prevents overheating of the body & helps regulate body temperature.
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Ceruminous glands- produce ear wax glands
Mammary glands Produce milk.
are modified apocrine sweat glands.
Physiology of the Skin
Protection - the epidermis provides a barrier to
fluid loss from the body.
• Barrier Function - intact skin prevents the
entry of micro-organisms into the body. laceration
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- a torn ragged wound
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Antimicrobial proteins - they act by piercing
holes in the outer membranes of microorganisms.
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Resistance to wear and tear - continuous
replacement of the outer epidermal cells that
wear off.
Continued
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Excretion- water, salt, and small amounts of
waste products such as urea.
• Vitamin D -can be synthesized in skin exposed
to sunlight ( also be obtained from the diet)
• Barrier- to ultraviolet light. The melanocytes
absorb UV radiation.
• Skin exposed to sunlight- wrinkled and crease.
• Dried blood and tissue fluid will create a scab.
Cancer
Ultraviolet light causes mutations at points on a
DNA strand.
• Three types of skin cancer corresponding
to three major types of skin cells:
• basal cells
• squamous cells
• melanocytes.
• Cancer of melanocytes - malignant
melanoma - is the most lethal variety, but also
the least common.
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Skin cancer
Sensory
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The integumentary system is well-supplied with
receptors for touch, pain, temperature, vibration
and pressure.
Sensory information is relayed to the central
nervous system via sensory nerves
3 types of receptors for touch- Meissner
corpuscle, Merkel disk, Krause end bulb.
2 types of receptors for pressure-Pacini
corpuscles, and Ruffini endings.
Free nerve endings- sense pain, heat and cold
(READ YOUR HANDOUT)
Burns-pg 76 in your text
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First-degree - red and very sensitive to touch, involve minimal tissue
damage Sun burn is a good example.
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Second-degree - affect both the outer-layer (epidermis) and the under
lying layer of skin (dermis) causing redness, pain, swelling and blisters.often affect sweat glands, and hair follicles.
Burns
Third-degree- affect the epidermis,
dermis and hypodermis, causing
charring of skin or a translucent
white color. Usually result in
extensive scarring.
Fourth degree- involves tissues
down to the bone. Chances of
survival –not good
Major concern with burns-fluid and
heat loss and bacterial infection.
“Rule of nines”
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You can estimate the body surface area on an adult that
has been burned by using multiples of 9.
Head = 9%
Chest/Abdomen (front) = 18%
Upper/mid/low back and buttocks = 18%
Each arm = 9%
Groin = 1%
Each leg = 18% total (front = 9%, back = 9%)
Major concern with burns-fluid and heat loss and
bacterial infection.