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BIO 110
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1) Thermoregulation – controlling body temperature
2) Blood reservoir – carries 8 – 10% of the blood when at
rest in an adult
3) Protection – a barrier to microorganisms, chemicals etc.
4) Sensation - sensory receptors provide us tactile
sensation, thermal sensation and pain
5) Excretion (sweating) and absorption (e.g., fat soluble
vitamins A,D,E & K, some drugs etc.)
6) Synthesis of Vitamin D
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Copyright 2010, John Wiley & Sons, Inc.
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Cutaneous membrane layers
1. Epidermis (epi, above)
2. Dermis
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Hypodermis (subcutaneous layer)
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Accessory structures
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Hair
Nails
Sweat gland
Sebaceous gland
Arrector pili muscle
Nerve fibers and sensory receptors
Cutaneous plexus (network of blood vessels)
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The structure of the skin, or integument, which consists of the cutaneous membrane and accessory structures
Accessory Structures
Cutaneous Membrane
The epidermis (epi, above)
consists of a stratified
squamous epithelium.
Hair shaft
Pore of sweat
gland duct
Papillary layer
Tactile corpuscle
Dermis
Reticular layer
Sebaceous gland
The dermis consists of a
papillary layer of areolar
tissue and a reticular layer of
dense irregular connective
tissue.
Arrector pili muscle
Sweat gland duct
Hair follicle
Lamellated corpuscle
The hypodermis
(subcutaneous layer or
superficial fascia) separates
the integument from the
fascia around deeper organs.
Note that this tissue is not
part of the integument.
Nerve fibers
Sweat gland
Artery
Fat
Vein
The network of
arteries and veins
connected to smaller
vessels servicing the
tissues of the integumentary system is the
cutaneous plexus.
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Copyright 2010, John Wiley & Sons, Inc.
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Epithelial cells that secrete a substance.
3 kinds of exocrine glands in the skin:
1) Sebaceous (oil) glands- sebum
2) Sudoriferous (sweat) glands- aprocrine and eccrine
3) Ceruminous glands- ear wax
© 2011 Pearson Education, Inc.
Copyright 2010, John Wiley & Sons, Inc.
© 2011 Pearson Education, Inc.
Copyright 2010, John Wiley & Sons, Inc.
1) Melanocytes
◦ Manufacture melanin
◦ Differences in skin pigmentation is not number of melanocytes
but varying cell synthetic activities
◦ Albinism (albin- = white) is the inherited inability of an
individual to produce melanin
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2) Hemoglobin, the oxygen-carrying pigment in red
blood cells
 Responsible for the blush (erythema) of the skin when
we are embarrassed
 Or the hyperemia when we apply heat
 Pallor results when the circulation is compromised e.g.,
shock, anemia
3) Carotene
 a yellow-orange pigment
 Precursor to Carotene is Vitamin A
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Copyright 2010, John Wiley & Sons, Inc.
The steps in the regeneration of the skin after injury
Initial Injury
Immediately after the
injury, mast cells in
the region trigger an
inflammatory
response.
After Several Hours
Bleeding
occurs at the
site of injury.
Epidermis
Dermis
The blood clot, or scab, that forms at the surface
temporarily restores the integrity of the epidermis and
restricts the entry of additional microorganisms into the
area. The scab is red due to the presence of trapped red
blood cells.
Macrophages patrol the
damaged area of the
dermis, phagocytizing
debris and pathogens.
Cells of the stratum
basale undergo rapid
divisions and begin to
migrate along the edges
of the wound in an
attempt to replace the
missing epidermal cells.
If the wound occupies an extensive area or involves a region
covered by thin skin, dermal repairs must be under way before
epithelial cells can cover the surface. Divisions by fibroblasts and
mesenchymal cells produce mobile cells that invade the deeper
areas of injury. Endothelial cells of damaged blood vessels also
begin to divide, and new capillaries grow in behind the
fibroblasts, enhancing circulation. The combination of blood clot,
fibroblasts, and an extensive capillary network is called
granulation tissue.
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The steps in the regeneration of the skin after injury
After One Week
After Several Weeks
Over time, deeper portions of the clot dissolve, and
the number of capillaries declines. Fibroblast
activity leads to the appearance of collagen fibers
and typical ground substance. The repairs do not
restore the integument to its original condition,
however, because the dermis will contain an
abnormally large number of collagen fibers and
relatively few blood vessels.
Fibroblasts
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Severely damaged hair follicles, sebaceous
or sweat glands, muscle cells, and nerves
are seldom repaired, and they too are
replaced by fibrous tissue. The formation of
this rather inflexible, fibrous, noncellular
scar tissue completes the repair process
but fails to restore the tissue to its original
condition.
Scar
tissue
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Cicatrix
◦ Growth of fibrotic tissue after damage, Scar
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Keloid
◦ Raised thickened mass of scar tissue
◦ Grows into surrounding dermis
◦ Most often in dark-skinned adults
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Fewer melanocytes
Thinning, drier epidermis
Diminished immune response
Thinning dermis
Decreased perspiration
Reduced blood supply
Slower skin repair
Fewer active follicles
Altered hair and fat distribution
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Boil (or furuncle) is a
skin disease caused by
the infection of hair
follicles, resulting in the
localized accumulation
of pus and dead tissue.
Individual boils can
cluster together and
form an interconnected
network of boils called
carbuncles.
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A cyst is a closed sac having a distinct membrane and
division on the nearby tissue. It may contain air, fluids,
or semi-solid material. A collection of pus is called an
abscess, not a cyst. Once formed, the cyst could go
away by itself or may have to be removed using
surgery.
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Tinea
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Tinea infections are caused by fungi.
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Athlete's foot (tinea pedis)
Tinea cruis- Jock itch
Tinea corpus- ringworm
Tiniea capitus- ringworm of the scalp
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Impetigo (sometimes impetaigo) is a superficial
bacterial skin infection most common among children
2 to 6 years old. It begins as a itchy red rash that
develops into pustules the form a yellow crust.
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A wart (also known as verruca) is generally a small,
rough tumor that can resemble a cauliflower or a solid
blister. Warts are common, and are caused by a viral
infection, specifically by the human papillomavirus
(HPV) and are contagious when in contact with the
skin of an infected person.
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An ulcer is a discontinuity of the skin exhibiting
complete loss of the epidermis and often portions of
the dermis and even subcutaneous fat.
Decubitus ulcers (Bedsores) occur when there is
consistent pressure against the skin. Very common in
bedridden patients.
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HSV
Infection with the herpes simplex virus
(HSV) is categorized into one of several distinct
disorders based on the site of infection. Oral herpes
(HSV I), vesicles (blisters) form on the face and mouth
and are called cold sores. Oral herpes is the most
common form of infection. Infection of the genitals
(HSV II), commonly known as herpes, is the second
most common form of herpes. Vesicles can appear on
the genitials.
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Chicken Pox
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Shingles
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Psoriasis is a chronic,
autoimmune disease
which affects the skin
and joints. It commonly
causes red scaly
patches on the skin.
Skin rapidly grows at
these sites and takes on
a silvery-white
appearance.
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Dermatitis is a blanket term meaning any
"inflammation of the skin" (e.g. rashes, etc.). There are
several different types of dermatitis. The different
kinds usually have in common an allergic reaction to
specific allergens. The term may be used to refer to
eczema, which is also known as dermatitis eczema or
eczematous dermatitis.
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The term eczema is
broadly applied to a
range of persistent skin
conditions.
 The following can be
characteristics of
eczema: redness, skin
edema (swelling),
itching and dryness,
crusting, flaking,
blistering, cracking,
oozing, or bleeding
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Hair follicles blocked by excess sebum and broken
down keratin cells from the base of the hair follicle.
Blackheads and whiteheads (comedones) can change
into pustules.
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Alopecia- Loss of hair,
baldness
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Hirsutism- excessive
Hairiness
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Albinism-a defect of
melanin production
that results in little or
pigment in the skin,
hair, and eyes.
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a defect of melanin
production that results
in little or no color
(pigment) in the skin,
hair, and eyes.
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Skin cancers (most common types of cancer)
◦ Types
 Basal cell carcinoma
 Most common skin cancer
 Originates in stratum basale in response to UV radiation
 Virtually no metastasis and most people survive
 Malignant melanoma
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Cancerous melanocytes
Commonly metastasize through lymphatic system
Detected early, 5-year survival is 99%
Not detected until metastasis, 5-year survival is 14%
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Methicillin-resistant
Staphylococcus Aureus
(MRSA) is a type of
staph bacteria that is
resistant to certain
antibiotics. This
condition very difficult
to treat.
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◦ Condition resulting in
poorly mineralized bones
◦ In children, develops from
not enough sunlight or not
enough dietary
cholecalciferol (Vitamin D)
 Uncommon in United States
◦ In elderly, skin production
of cholecalciferol decreases
by 75%
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Pediculosis- Lice
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Scabies- Itch Mite
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Rosacea is a chronic
skin condition
characterized by
redness, swelling and
skin sores that look like
acne.
Sometimes called
“adult acne”
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A wheal is small, itchy swelling of the skin.
Can relate to an insect bite or hives
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A contusion (bruise) is a type of hematoma of tissue[in
which the blood vessels are damaged by trauma,
allowing blood to leak into the surrounding interstitial
tissues.
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