Download Layers of Skin - Liberty Union High School District

Integumentary System
• This body system connects to the other
systems in many ways!! See handout pg 45.
• This system consists of the skin and its
accessory organs, hair, nails, and cutaneous
glands.
Functions of the Integumentary
System
1. Resistance to trauma and infection
(epidermal cells have lots of KERATIN (protein) strong!
2. Barrier to liquids
3. Vitamin D synthesis
4. Sensation
5. Thermoregulation
6. Social functions 
Layers of the skin
Epidermis: is the top five layers of skin, and contains five different types of cells
1A. Dead cells (keratinocytes)
1B. Living Keratinocytes :most of the epidermal cells, they
produce keratin and use UV light to convert a steroid to pre-vitamin D
Stratum Corneum
2. Dendritic cells (Langerhans cells): microphages that fight
toxins, microbes, and other pathogens that penetrate the
skin, (Immune alarm) Stratum Spinosum
3.
Tactile cells (Merkel cells) are receptors for touch Stratum Basale
4.
Stem Cells: they go through mitosis to produce keratinocytes
Stratum Basale
5. Melanocytes : produce melanin that reacts to sun light to increase
sun burn protection Stratum Basale
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See table 6.1 on page 194
2nd layer of skin: Dermis
• Dermis: lies below epidermis, has large amounts
of fibrous connective tissue.
• Composed mainly of collagen, elastic, and
reticular fibers.
• The connective tissue in this layer contains: blood
vessels, sweat glands, hair follicles, nail roots,
sebaceous glands, smooth muscles,(Piloerector),
pressure receptors and nerve endings
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3rd Layer of the Skin: Hypodermis
• The hypodermis is often called the superficial
fascia
• The fascia contains large amounts of adipose
• ( subcutaneous fat), connective tissue, blood
vessels
• Adipose tissue pads the body, is a thermal
insulation and energy store and is the
preferred injection site due to it vascular rate
• Connective tissue binds the skin to the
underlying tissues
Skin Color
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Skin color is determined by amount of
melanin produced by melanocytes.
There are basically 2 colors:
Eumelanin= Brown Black
Pheomelanin= Red/Yellow (sulfur containing)
• Other factors are hemoglobin (red/pink hues) and
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carotene (yellow/orange…in veggies)
Skin Color :
can indicate disease or disorders
• 1. Cyanosis—blueness due to O2 deficiency
• 2. Erythem—abnormal redness, blush, sunburn
• 3. Pallor---- ash, pale, too little blood flow, dermal
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collagen shows through
4. Albanism—lack of melanin..genetic recessive
5. Jaundice– yellowing of skin due to high levels of
billirubin, hemoglobin break down product
6. Bronzing—golden brown, Addison Disease, lack of
glucocorticoid hormone.
7. Hematoma—bruising, purplish, clotted blood showing
through.
Types of Skin Markings
• Friction Ridges: markings on fingertips, form
during fetal development
• Flexion Lines: Lines on digits, palms, wrists,
elbows
• Freckles: flat melanized patches of skin that
vary with heredity and sun exposure
• Moles: same as freckle but elevated
• Hemangiomas: birth marks caused by begnin
tumors of dermal blood capillaries
Accessories of the skin:
Hair, Nails, and CutaneousGlands
• Hair and Nails are composed of mostly dead
keratinized cells.
• Skin (stratum corneum has soft keritin)
• Hair and Nails made of more compact, hard
keritin, cross linked between keritin
moelcules.
Cross section of a hair
Structures of hair
Basis of hair color and texture
• See page 199
• Hair grows from the hair matrix just above the
hair bulb.
• The hair bulb is near vascular connective
tissue which provides hair with it’s nutrients.
Nail structure
• What are the Accessory Structures: Nails?
– Nail body
• Dense mass of keratinized cells
– Nail bed
– Nail root
– Cuticle (eponychium)
– Lunula
Glands of the skin
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The skin has 5 types of Glands
1. Merocrine Sweat Glands
2. Apocrine Sweat Glands
3. Sebaceous Glands
4. Ceruminous glands
5. Mammary Glands
Sweat Glands
• Merocrine (eccrine)
• Apocrine
• Most numerous
• Produces watery 99%
perspiration for cooling
• 3-4X106 all over
• Palms, soles, forehead
• pH 4-6
• Tubular gland with
twisted coil
• Narrow lumen, opens at
pore on skin
• Occur in groin, anal,
axilla, beard area.
• Produces thicker soln.
with fatty acids
• Are scent glands
• Large lumen, opens to
hair follicle
Sebaceous Glands
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Produce an oily secretion called SEBUM
Flask shaped, located higher up in dermis
Short ducts opening to hair follicles
Keeps skin and hair from becoming dry
(brushing hair spreads this)
Lanolin in moisturizers is sheep sebum
Ceruminous Glands
• Found only in external ear canal
• Secretion combines with sebum &dead
epithelial cells to make ear wax CERUMEN
• Waterproofs the ear canal and is anti-bacterial
Mammary Glands
• Milk producing glands in female breasts
• Are modified apocrine glands which produce
richer secretions
• For summary see chart 6.2 on page 203
Skin Disorders
see chart 6.3
• What are the Effects of UV Radiation?
– Beneficial effect
– Activates synthesis of vitamin D3
– Harmful effects
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Sun burn
Wrinkles, premature aging
Malignant melanoma
Basal cell carcinoma
Skin Cancer
• Cancer: rapid mitotic division of cells caused by a
trigger environmental, genetic
• Skin cancer: is caused by exposure to UV rays.
There are three types named for tissue affected
• 1. Basal carcinoma:
• most common,
• easiest to remove.
• Appears as a red shiny bump that enlarges with
depressed center
• 2. Squamous Cell Carcinoma
• found usually on scalp, ears, lip, back of
hands.
• Has red scaly appearance with concave center.
• High survival rate with early detection,
• will metastasize to lymph nodes highly lethal
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3. Malignant melanoma
most deadly
arises in melanocytes in moles.
Fast to metastasize
lethal without immediate treatment
Recognizing Malignant Melanoma
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A= Asymmetry
B= Border irregularity
C= Color (brown, black, tan, red, purple)
D= Diameter (6mm)
Burns and Healing
• Burns: Leading cause in accidental death,
death results from fluid loss and the toxic
effect of eschar
• First degree: found in only epidermis,
epidermis turns red, edema and pain, heals in
a few days
• Second degree: or partial-thickness burns due
to damage only in top of dermis layers, has
blisters can scar and takes about 2 weeks to
heal
• Third degree: or total thickness burns, turns
black, skin can only grow from sides of
damaged area so grafts are needed,
debridement must occur in 24 hours, then
toxic
Healing and Repair on injury to skin
What are the Four Stages in Skin
Healing?
1. Inflammation
• Blood flow increases
• Phagocytes attracted
2. Scab formation
3. Cell division and migration
4. Scar formation
Bleeding occurs at the site of injury
immediately after the injury, and mast cells in
the region trigger an inflammatory response.
After several hours, a scab has formed and cells of the
stratum germinativum are migrating along the edges
of the wound. Phagocytic cells are removing debris,
and more of these cells are arriving with the
enhanced circulation
in the area. Clotting around the edges
of the affected area partially isolates
the region.
One week after the injury, the
scab has been undermined by
epidermal cells migrating over
the meshwork produced by
fibroblast activity. Phagocytic
activity around the site has
almost ended, and the fibrin clot
is disintegrating.
After several weeks, the scab
has been shed, and the
epidermis is complete. A shallow
depression marks the injury site,
but fibroblasts in the dermis
continue to create scar tissue
that will gradually elevate the
overlying epidermis