The Skin as an Organ

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The Skin as an Organ
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The integumentary system (skin) Roles protectio
n maintenance of normal body temperature storage
(of fat) synthesis (of vitamin D) excretion
(of salts, water and wastes in sweat) sensory
perception
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Tissues of the skin epidermis- straitified
squamous epithelium basement membrane dermis-
largely connective tissue many nerves and blood
vessels smooth muscle hypodermis- adipose
tissue and more loose connective tissue
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Epithelium deepest layer (stratum germinativum,
or stratum basale)- rapidly dividing
cells stem cells present outermost layer-
stratum corneum dead, keratinized
cells Melanocytes in stratum basale- produce
pigment absorbs UV radiation surround
nucleus Cells vary in amount of melanin they
produce
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Epidermal cells make a precursor form of vitamin
D Modified in liver and kidney Required for
bone formation Protection includes immune
protection Langerhans (dendritic)
cells keratinocytes specialized T cells
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Dermis- capillaries and nerves deeper layers are
dense connective tissue superficial layers are
loose Subcutaneous layer loose connective and
adipose tissue shock absorption, insulation,
energy
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Accessory structures Originate in epidermis
(hair follicle), extend into dermis arrector
pili muscle attached Hair is pigmented
determined by amount of melanin (Red hair
requires a different pigment) Pigment production
decreases with age Several specialized types of
hair
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Nails Nail bed overlaid by nail plate Nail
growth originates from root cells
become keratinized Cuticle is formed from
stratum corneum
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Two types of exocrine glands Sebaceous- sebum
(oil, wax) associated with hair follicles helps
maintain pliability of skin Sweat
glands apocrine (armpits, groin) merocrine
(eccrine)- widely distributed important for
maintaining body temperature
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Aging and the integumentary system Declines
in Cell division in stratum basale Melanocyte
production Glandular activity Hair follicle
function Elastic fiber function in dermis Blood
supply to skin Rate of repair
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Problems of skin Lesions infections (bacterial,
viral, fungal,parasitic) inflammatory
reactions allergens Hyperkeratinization Tumors
basal cell (stratum basale) squamous
cell melanoma
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Trauma abrasions, incisions, lacerations Repair
inflammation scab formation fibroblast
activity (scar formation) Burns- severity
depends on depth of damage Rashes- so many
causes!
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Checkpoint 1Stop and write the answers in your
journal!

• Sketch, label and Describe the parts of a
  fingernail.
• Skin glands produce _______
• 6. The cuticle of the nail is made of this
  tissue layer __
• 7. The outermost portion of the skin is the
• 8.Perspiration is produce by these
  glands_______________

• 1. What are the roles of the skin?
• 2. What are the tissues of the skin?
• 3. Sketch and label the skin!

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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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Checkpoint 2Stop and write the answers in your
journal!

• 1. Cells that are responsible for touch
  /sensation are called __________________
• 2. The layer that contains cells skin that are
  active in the immune process are ________
• 3. The cells that produce the pigment responsible
  for skin color are _______________

• The primary function of hair is___________________
  
• Sebaceous glands produce _____________
• 6. The cuticle of the nail is made of this
  tissue layer ______________
• 7. The inside portion of the skin is the
• 8.Perspiration is produce by these
  glands________________

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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/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
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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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Integumentary Lab Report

1. In which layer of skin are blood vessels located?
   
2. Where does epithelium regeneration begin?
3. Sketch and label a diagram of the skin
4. List the layer of the epidermis in order from top
   to bottom.
5. Explain the relationship between the cells,
   tissues, and glands of the integumentary system.
   ( In 4 sentences!)

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Checkpoint 3Stop and write the answers in your
journal!

• 1. The epidermis is primarily made of this type
  of tissue __________________
• 2. The dermis is made up of this type of tissue
  _________
• 3. This can be found in the subcutaneous layer of
  the skin ________, ____________
• 4. The corpuscles of touch ( Meissners
  corpuscles) are found in this area of the
  skin________________
• 5. The skin layer of the epidermis that contains
  cells capable of continued cell division is
  called______________

• 6. The outermost layer of the epidermis that is
  composed of dead cells that flake off
  is______________
• 7 The layer that contains cells for fighting
  infection is called ___________________
• 8. Cells that are responsible for touch
  /sensation are called _____________________
• 9 The layer that contains cells skin that are
  active in the immune process are ________
• 10 The cells that produce the pigment responsible
  for skin color are _____________