Transcript Integumentary System

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All humans have roughly the same number of
melanocytes. Color is based on the activity,
not the number.
Increase in Melanin production in those
exposed to more UV radiation, decreased
Melanin production in those exposed to less
UV radiation
Melanin is a “natural suncreen”. Dark skinned
people seldom have skin cancer due to its
effectiveness, however when they get it, it is
more deadly.
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Tanning is the body’s built in protective
mechanism, it leads to increased melanin
production and protection from UV radiation.
Albinos genetically can’t produce melanin
and have to be extremely cautious about
exposure to the sun.
Skin color is controlled by many factors:
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Amounts and kind of pigment present
Amount of carotene present
Amount of oxygen bound to hemoglobin
Emotional stimuli
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Cyanosis- when blood is poorly oxygenated and
skin appears blue
Redness- can indicate embarrassment, fever,
hypertension, inflammation or allergy
Pallor (paleness)-emotional stress(fear, anger),
anemia, low blood pressure, impaired blood flow
into the area
Jaundice (yellow)-liver disorder
Bruises (black and blue)-blood escapes
circulatory system and clots in tissue spaces.
◦ Hematomas-unusual bruising-VitaminC deficiency or
hemophilia are common causes
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Sebaceous Glands-oil glands, found
everywhere but palms of hands and soles of
feet
◦ Sebum-mixture of oily substances and fragmented
cells, keeps skin soft, prevents brittle hair, kills
bacteria.
◦ During adolescence hormones increase amount of
oil produces and skin is oilier at that time in life.
◦ Acne is infection of the sebaceous glands
◦ “Cradle cap” is due to overactive sebaceous glands
in infants. Yellow brown crust, comes off as
dandruff.
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2 kinds of sweat glands (Sudoriferous glands)
◦ Eccrine- produces primarily water, it is odorless and
actually inhibits bacterial growth. Helps body
regulate temperature. You can lose 7L of water on
a hot day
◦ Apocrine-produces fatty acids and proteins which
provides a food source for bacteria on skin. The byproduct of those bacteria is body odor.
◦ Sweat reaches the skin by a duct that opens as a
pore.
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Functions:
◦ Guards head against bumps
◦ Eyelashes protect the eyes
◦ Keeps foreign particles out of respiratory tract
◦ In the past helped with keeping the body warm.
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It is produced by a hair follicle. Root is
enclosed in follicle, the shaft is the part
projecting from the surface.
Hair is formed by well-nourished stratum
basal epithelial cells in the matrix. The
farther away they get from the growing
region, they become keratinized and die.
Consists of central core (medulla) surrounded
by cortex layer, surrounded by a cuticle.
◦ Cuticle provides strength, when it wears away, you
get split ends.
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Melanocytes determine hair color
Texture is determined by the shape of the
hairshaft:
◦ Oval hairshaft – smooth hair
◦ Flat hairshaft- curly, kinky hair
◦ Hair is all over the body with exception of palms of
hands, soles of feet, lips
◦ Hormones account for development of hairy regions
such as armpits
Arrector pili- bands of smooth muscle connect to
hair follicle and dermal tissue, when muscles
contract they form “goose bumps”
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Scalelike modification of epidermis- mostly
nonliving material
They have a free edge, a body and a root,
border is overlapped by skin folds.
Nails are transparent and nearly colorless but
look pink due to rich blood supply in the
dermis
White crescent is called LUNULA
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Skin can develop more than 1000 disorders
with many causes
Athlete’s foot- fungus
Boils- staph infection-bacteria
Cold Sores- virus
Contact Dermatitis- chemicals, allergy
Impetigo- staph infection, very contagious,
especially common in children
◦ Psoriasis-unknown cause- red lesions covered with
dry, silvery scales, can be disfiguring.
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Tissue damage and cell death caused by heat,
electricity, UV radiation and some chemicals.
Damages due to burns:
◦ Body loses fluids as they seep from burned
surfaces, dehydration and electrolyte imbalance
follows. Can lead to kidney shutdown and
circulatory shock.
◦ Infection can set in after 24 hours and your immune
system is weakened because of the burn.
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1st Degree- only epidermis is damaged. Red and
swollen. Usually not that serious.
2nd Degree- injures epidermis and upper region
of dermis. Skin is red and painful, blisters
appear. Regrowth of epithelium can occur.
Usually no scars.
3rd Degree- full thickness of skin burns, appears
gray-white or blackened. Nerves are destroyed.
Regeneration isn’t possible, must have skin graft.
Facial burns are dangerous when Respiratory
pathways are effectedsince they can swell and
cause suffocation.
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Subcutaneous tissue decreases, intolerance to
cold
Skin is drier
Skin is thinner- more likely to bruise
Lost elasticity- allows bags under eyes
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Hair Loss- by 50, the number of hair follicles
has dropped by 1/3 and continues to decline
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Male pattern baldness is an obvious baldness
that increases as you age
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Graying- amount of melanin in hair decreases
or becomes entirely absent.
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Causes of graying or hair loss:
◦ Anxiety
◦ Protein deficient diet
◦ Chemotherapy
◦ Radiation
◦ Excessive Vitamin A
◦ Fungal disorders
This is usually not permanent when it comes to hair
loss.