Integumentary System

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Integumentary System

• Anatomy
• Fall 2005

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Integumentary System

• The skin covers the entire surface of the human
  body.
• An adults skin covers about 1.8 square meters of
  surface area.
• The skin has several accessory organs, which is
  why it is referred to as the integumentary system.

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Integumentary System
The Skin has two regions the epidermis and the
dermis. The hypodermis lies below the skin.
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Structure of the Skin--Epidermis

• The epidermis, the outer region of the skin, is
  made up of stratified squamous epithelium.
• New cells continually produced in the stratum
  basale of the epidermis are pushed outward and
  become the keratinized cells of the stratum
  corneum.

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Structure of the Skin--Epidermis

• Stratum Basale
• Basal cells, which lie superior to the dermis,
  are constantly dividing and producing new cells.
• As they move farther from the dermis, they
  receive less and less oxygen and nutrients and
  eventually die and sloughed off.
• Langerhan cells are macrophages found deep in the
  epidermis. They feed on microbes and then travel
  to lymphatic organs, where they stimulate the
  immune system to react.
• Melanocytes are found deeper in the epidermis.
  They produce melanin, the pigment responsible for
  skin color.

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Structure of the Skin--Epidermis

• When skin is exposed to sun, melanocytes produce
  more melanin to protect the skin from damaging UV
  radiation.
• A pigment called carotene is present in epidermal
  cells and gives the skin of Asians a yellowish
  hue.
• The pinkish color of fair-skinned people is due
  to the pigment hemoglobin in the red blood cells
  in the capillaries of the dermis.

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Why do some people freckle when exposed to the
sun?
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What is the name of the hereditary disease where
an individual lacks the ability to produce
melanin?
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Structure of the Skin--Epidermis

• Stratum Corneum
• As cells are pushed toward the surface of the
  skin, they become flat, forming the tough,
  uppermost layer of eh epidermis, the stratum
  corneum.
• Cells are hardened by a process called
  keratinization, which waterproofs the cells with
  a protein called keratin.
• Keratinization protects the body from water loss
  and water gain, allowing individuals to live in
  the desert or a tropical rain forest without
  damaging our inner cells.

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Over much of the body, keratinization is minimal,
but a couple of parts in particular are extremely
waterproofed. What are they?
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Structure of the Skin--Dermis

• The dermis, which is composed of dense irregular
  connective tissue, lies beneath the epidermis.
• It contains collagenous and elastic fibers, blood
  vessels, and nerve fibers.

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Why does a person blush?
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Structure of the Skin--Hypodermis

• The hypodermis is made up of loose connective
  tissue and adipose tissue, which insulates the
  body from heat and cold.
• Excessive adipose tissue results in obesity.

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At what stage in life would you have the most
adipose tissue?
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Accessory Structures of the SkinHair, Nails, and
Glands

• Both hair and nails are produced by the division
  of epidermal cells and consist of keratinized
  cells. Hair color is a result of melanin.
• Sweat glands are numerous and present in all
  regions of the skin. Sweating helps lower body
  temperature.
• Sebaceous glands are associated with a hair
  follicle and secrete sebum, which lubricates the
  hair and skin
• Mammary glands located in the breasts produce
  mild after childbirth.

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Marie Antoinettes hair supposedly turned white
overnight after she heard she would be sent to
the guillotine. Explain why you believe or
disbelieve this story.
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Hair

• Hair is found on all parts of the body except the
  palms, soles, lips, nipples, and portions of the
  external reproductive organs.
• The portion of a hair that within the follicle is
  called the root. The portion that extends beyond
  the skin is called the shaft.

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Hair

• When women produce more male sex hormone than
  usual, they can develop hirsutism, a condition
  characterized by excessive body and facial hair.
• In males, baldness (Alopecia) occurs when the
  hair on the head fails to regrow.
• The lifespan of a head hair is approximately
  three to four years.

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A poor diet, or excessive dieting, can cause a
persons hair to fall out. How long could it take
to regain a beautiful head of hair?
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Nails

• Nails grow from special epithelial cells at eh
  base of he nail region called the nail root.
• The visible portion of the nail is called the
  nail body.
• The cuticle is a fold of skin that hides the nail
  root.
• Nails grow about 1mm per week.

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Glands

• There is normally between 90 (leg) and 400
  (palm/soles) sweat glands per square cm.
• Every hair is attached to at least one sebaceous
  gland.
• Acne vulgaris is the result of inflammation of
  the sebaceous gland.

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Disorders of the SkinSkin Cancer

• Skin cancer, which is associated with ultraviolet
  radiation occurs in three forms. Basal cell
  carcinoma and squamous cells carcinoma can
  usually be removed surgically. Melanoma is the
  most dangerous form of skin cancer.

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UV rays are associated with cancer of the skin.
Should a person prevent all exposure to UV light?
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(No Transcript)
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Danger Signals for Cancer

• C hange in bowel or bladder habits
• A sore that does not heal
• U nusual bleeding or discharge.
• T hickening or lump in breast or elsewhere
• I ndigestion or difficulty in swallowing
• O bvious change in wart or mole
• N agging cough or hoarseness

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Disorders of the SkinStaphylococcal Infections
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Disorders of the Skin

• Athletes Foot caused by a fungal infection that
  usually involves the skin of the toes and soles.
• Impetigo a highly contagious disease occurring
  most often in young children.
• Psoriasis a chronic condition in which the skin
  develops pink or reddish patches covered by
  silvery scales due to overactive cell division.
• Dandruff a skin disorder not caused by a dry
  scalp, but by an accelerated rate of
  keratinization in certain areas of the scalp.

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Wound Healing
After a blood clot forms, a protective scab
develops. Fibroblasts and white blood cells
migrate to the wound site
A deep wound ruptures blood vessels, and blood
flows out and fills the wound
New epidermis forms, and fibroblasts promote
tissue regeneration
Freshly healed skin
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Functions of the IntegumentarySystem

• Protection. The skin provides protection against
  abrasion and UV light. It also prevents the entry
  of microorganisms and dehydration by reducing
  water loss from the body.
• Sensation. The integumentary system has sensory
  receptors that can detect heat, cold, touch,
  pressure, and pain.
• Vitamin D production. When exposed to UV light,
  the skin produces a molecule that can be
  transformed into vitamin D.

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Functions of the IntegumentarySystem

• Temperature regulation. Body temperature is
  regulated by controlling blood flow through the
  skin and the activity of sweat glands.
• Excretion. Small amounts of waste products are
  lost through the skin and in gland secretions.

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Why do peoples nose and ears turn red on cold
winter days?
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When melanin is evenly distributed, tanning
occurs. When melanin collects in specific areas,
then freckles occur.
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Albinism
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Hands/Soles of Feet
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A blush is a result of a rush of blood to vessels
in the dermis layer.
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Infancy (baby fat)
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The story is impossible. Hair color results form
melanin that is added to the hair in the hair
bulb as the hair grows. The hair itself is dead.
To turn white, the hair must grow out without the
addition of melanin. This, of course, takes
considerably more time than one night.
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3 to 4 years
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No. UV light stimulates the production of a
precursor molecule in the skin that is modified
by the liver and kidneys into vitamin D. Without
enough vit. D, one would suffer from rickets
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On cold days, skin blood vessels of he ears and
nose can dilate, bringing warm blood to the ears
and nose, thus preventing tissue damage from the
cold. The increased blood flow makes the ears and
nose appear red.