The Integumentary System

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The Integumentary System

• Skin, Hair, Glands, Nails
• Anatomy Physiology Ch. 5

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Learning Targets

• Identify the anatomical structures of the
  integumentary system.
• Explain the role of skin and all of its accessory
  organs.
• Describe the diseases/disorders
• of the integumentary system.

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Human skin..

• is the largest organ.
• it serves as a protective covering.
• it helps regulate body temp.
• it prevents water loss.
• it houses sensory receptors.
• it excretes wastes.

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Integumentary System

• Three layers
• Skin
• Epidermis 2. Dermis
• 3. Hypodermis (Subcutaneous layer)
• Adipose
• Accessory Structures
• Hair - Nails -sebaceous glands
• sweat glands (4 types)

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• The skin is composed of 3 layers the epidermis
  (superficial), the dermis (middle) and the
  hypodermis (deep).

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Epidermis

• composed of stratified squamous.
• lacks blood vessels no vascularization.
• prevents water loss by secreting protein,
  keratin.
• keratinization of cells takes about 2 weeks.
• No innervation lacks nerves.

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Keratinized stratified squamous
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Epidermis (cont)

• Contains cells called melanocytes that produce
  melanin (absorbs light energy protects deeper
  cells) melanin gives skin its color.

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Melanocyte
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Skin Color

• All people have similar numbers of melanocytes.
• Skin colors result from differences in the amount
  of melanin that melanocytes produce and the
  distribution size of the melanin granules.
• Albinism - inability to produce melanin.

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Dermis

• Is made up of two layers.
• Top layer (papillary layer) composed of areolar
  or loose connective tissue.
• Bottom layer (reticular layer) composed of dense
  connective tissue.
• Well vascularized innervated.
• Also contains accessory structures such as hair
  follicles, sebaceous glands, and sweat glands.

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Hypodermis

• Made of adipose tissue and some loose connective
  tissue.
• Insulates body from losing too much heat.
• Also known as the subcutaneous layer.
• Men and women store subcutaneous fat differently.

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Hair

• Composed of epidermal cells that have keratinized
  and died .
• Hair color is determined by the type and amount
  of pigment the melanocytes produce.
• Arrector pili muscle - surrounds hair follicle
  contracts when a person is cold or frightened.
  What are goose bumps?

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Sebaceous Glands

• a gland located around the hair follicle which
  secretes its contents when contracted by the
  arrector pili.
• secrete an oily mixture of fat and cellular
  debris called sebum which keeps the hair and skin
  soft, pliable, and waterproof.
• this is why hair gets oily when not washed.

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Nails

• Composed of dead stratified squamous epithelial
  cells which are extremely keratinized.
• Nail production occurs at the nail root which is
  underneath the skin and proximal to the visible
  nail.
• Nails are basically clear and appear pink over
  skin because of underlying blood vessels.

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Sweat Glands (Exocrine Glands)

• Eccrine Glands
• respond to elevated body temp. due to heat or
  exercise.
• cool by allowing water to be evaporated from skin
  lowering temp.
• common on forehead, neck, and back.

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Sweat Glands (Exocrine Glands)

• release fluids thru pores.
• gland located in dermis but releases fluid
  through tube onto the top of the epidermis.
• sweat water salts (mainly sodium chloride)
  and other wastes.
• Where do you have the most eccrine glands?

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Sweat glands (cont.)

• 2. Apocrine glands.
• active when a person is emotionally upset,
  frightened, or in pain.
• found under the armpits and in the groin.
• sweat is food for bacteria, which just increases
  the bad smell.

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Other Integumentary Glands

• - Ceruminous glands - secrete ear wax to trap
  foreign particles before reaching the ear drum.
• Why does ear wax smell bad?
• - Mammary glands - secrete milk.

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Regulation of Body Temperature

• Regulation is important b/c heat affects the rate
  of metabolic reactions.
• When temp rises above the set point, dermal blood
  vessels dilate (get larger) and glands secrete
  sweat.
• When temp drops below the set point, dermal blood
  vessels constrict (get smaller) and glands become
  inactive.
• WHAT TYPE OF FEEDBACK IS THIS?

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Healing of Wounds

• Skin injuries trigger inflammation blood vessels
  dilate and become more permeable, forcing fluids
  to leave the blood vessels and enter the damaged
  tissues.
• WHAT TYPE OF FEEDBACK IS THIS?
• Dilated blood vessels supply the damaged cells
  with more oxygen and nutrients this speeds
  healing.
• More platelets are supplied to clot blood.
• More white blood cells needed to fight infection.

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Skin cancer

• There are three main types of skin cancer basal
  cell carcinoma, melanoma, and squamous cell
  carcinoma.
• Both UVA and UVB contribute to skin cancer.
• Basal cell carcinoma is the most prevalent
  affecting over 2 million Americans a year.
• Basal cell carcinoma develops in the cells of the
  basement membrane typically due to sun exposure.

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Melanoma

• Melanoma is the most deadly form of skin cancer
  while also being the most rare.
• 120,000 new cases are diagnosed in the U.S. each
  year.
• If caught early it is usually treatable, however
  if it spreads to other parts of the body
  treatment becomes much more difficult.
• Melanoma develops in the melanocytes located in
  the epidermis.
• Melanoma usually appears black or brown.

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Squamous cell carcinoma

• Squamous cell carcinoma is the second most
  prevalent type of skin cancer.
• It originates in squamous cells of the epidermis.
• It is more prevalent in areas exposed to the sun
  and in people with lighter skin.
• Twice as many men as women develop this type of
  skin cancer.
• http//www.skincancer.org/skin-cancer-video.html