Integumenatry System

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Integumenatry System
Ch 5
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The Skin as an Organ
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Function

• Protection- mechanical, chemical, bacterial
• Body temperature regulation
• Prevent water loss
• Metabolic- synthesize vitamin D
• Cutaneous Sensation
• Blood reservoir
• Excretion
• Prevent UV damage

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The Skin
An organ, cells constantly dying and being
replaced

• Facts
• Weighs 9-11 lbs
• s.a. 1.5-2m2
• 1 cm2 has 70 cm blood vessels, 55 cm
• nerves, 100 sweat glands, 15 oil glands, 230
  sensory receptors
• New skin produced in 25-45 days

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The Epidermis
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Cells of the Epidermis

• Keratinocytes (90)- waterproofs protects skin,
  nails, hair, stratum corneum
• Melanocytes (8)- produce melanin
• Merkel Cells- slow mechanoreceptors
• Langerhans Cells- immunological defense

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Layers of the Epidermis

• Stratum Corneum
• Stratum Lucidum
• Stratum Granulosum
• Stratum Spinosum
• Stratum Basale- (Germinativum)

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Layers of the Epidermis
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The Dermis
Dermis
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Layers of the Dermis

papillary dermis
reticular dermis
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Components of the Dermis
a. Cellular Fibroblasts (synthesize collagen,
elastin, and reticulin), histiocytes, endothelial
cells, perivascular macrophages and dendritic
cells, mast cells, smooth muscle, and cells of
peripheral nerves and their end-organ receptors.
b. Fibrous Collagen reticulin - provide
tensile strength Elastic fibers- provide for
restoration of shape after a deformation c.
Ground substance glycosaminoglycans hyaluronic
acid, chondroitin sulfate, and dermatan sulfate.
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The Hypodermis
Hypodermis
This layer contains adipose tissue and serves to
attach the dermis to its underlying tissues.
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Skin Color
Some variations in human skin color
(Sub-Saharan African, Indian, Southern European,
and Northwest European)
Skin color due to Melanin, Carotene Hemoglobin

• Melanin Pigments
• Eumelanin
• Phaeomelanin
• gt EumelaninPhaeomalanin- darker skin and hair
  color
• lt EumelaninPhaeomalanin- lighter skin and hair
  color

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Skin Color
Human complexions are generally classified into
six skin types
I -light skinned, burns easily, never tans II -
light skinned, burns easily, tans some III -
light skinned, burns occasionally, tans well IV -
light skinned, tans well, rarely burns V - brown
skinned (Asian, Indo-Asian, Chinese, Japanese),
tans well, burns rarely, can sunburn after
prolonged exposure to UVR VI - black skinned
(Afro-Caribbean), deeply pigmented, can burn
after prolonged exposure to UVR
25 US pop
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Skin Color Conditions

• Cyanotic
• Jaundice
• Erythema
• Pallor

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Skin/Hair Color Pigmentation

• Pigmentation levels usually increase with age.
• - exception premature graying
• Normal pigmentation may be altered by genetic
  defects or by acquired diseases.
• -Hyperpigmentation- age spots
• -Hypopigmentation- vitiligo,
• albinism

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Skin/Hair Color Pigmentation

• External agents can also alter skin color.
• lightening agents
• carotene
• dyes
• Some internal compounds--such as the byproducts
  of hemoglobin metabolism--may color the skin.

Sunless tanning
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Skin Cancer

• Malignant melanoma
• 2 of all cancers
• Risks
• Skin type
• Sun exposure
• Family history
• Age
• Immunological status

Normal mole Melanoma

• A asymmetry
• B border
• C color
• D diameter

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Skin Appendages
Sweat Glands

• Eccrine (merocrine) glands- sweat
• Apocrine glands- axillary anogenital areas
• Ceruminous glands- ears canal
• Mammary glands- female reproductive glands

Sweat glands
Ceruminous glands
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Skin Appendages
Sebaceous
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Skin Appendages
Hair
Hair shaft
Sebaceous gland
Hair root
Hair bulb in follicle
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Skin Appendages
Nail
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Burns
1st Degree epidermal damage Ex. sunburn 2nd
Degree epidermis upper dermis Ex.
blisters 3rd Degree entire thickness of skin
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Burns
Skin replacement http//www.youtube.com/watch?v
eXO_ApjKPaI
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Tissue Repair

• Blood vessels dilate
• WBC clotting agents released
• Scab forms

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Tissue Repair

• Granulation tissue forms
• Capillary beds invade clot
• Clean up begins

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Tissue Repair

• Scar area has contracted
• Epithelium regeneration begins

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INQUIRY

• In which lay of skin are blood vessels located?
• Where does epithelium regeneration begin?
• What color is a persons skin if they are
  cyanotic?
• List the layer of the epidermis in order from top
  to bottom.
• What is the primary tissue of the hypodermis?

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