Integumentary System
• Sheet-like membranes of epithelium,
connective tissue, and other organs
Types of membranes
• Serous - lines body cavities that don’t open
to the outside
– Parietal and visceral
– secretes serous fluid. What’s the purpose of
serous fluid?
– Where would this be found?
• Peritoneum
• Pleura
• pericardium
Types of membranes
• Mucous - lines cavities/tubes that open to
the outside
– Stratified squamous or simple columnar
– secretes mucus. Purpose?
– Specific locations?
Types of membranes
• Synovial - lines joint cavities
– secretes synovial fluid to lubricate joints
– location?
• Cutaneous - skin
Skin
• One of the largest organs
• What are some functions (pg 111)?
• Consists of the epidermis, dermis,
hypodermis (subcutaneous)
• What is the difference between a
subcutaneous (hypodermic) and a
intradermal injection?
Epidermis
• Consists of stratified squamous. What can
be said about the blood supply?
• New epidermis is created every 25-45 days
• Stratum basale
– Receives the most noursihment
– Cell division
– ~25% of cells are melanocytes
Epidermis
• Stratum Spinosum
– Cell division, how would it compare to the basale?
• Stratum Granulosum
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Abundance of granules (glycolipids and keratin)
What is the purpose of keratin? Glycolipid?
Loses nourishment
What does this result in?
keratinization - the cells fill with keratin protein
Keratinocytes
Epidermis
• Stratum lucidum
– Areas with thick skin possess this layer. Where
would this be? What areas would not possess
this layer?
• Stratum corneum - 3/4 of thickness
– Functions?
– What can be said about the cells here?
– Average person sheds ~40 lbs of skin in their
lifetime
Skin Color
• specialized cells (melanocytes) produce the
pigment melanin (mainly found in the
basale layer)
• melanin ranges from yellow to reddishbrown
– absorbs light radiation
– Significance?
Skin Color
• Melanocytes possess extensions that transport
melanin between epidermal cells
• Cells in stratum basale phagocytize melanin
– Causes?
• UV radiation destroys the bodies folic acid
reserves
• What other effects does UV radiation have? What
layer would be impacted most?
Skin Color
• Most people possess the same number of
melanocytes.
• What would cause the differences in skin
color?
• Determined by genetics and environment
• How could blood affect skin color?
• Carotene can effect skin color.
• What are freckles?
Dermis
• binds the epidermis to underlying tissues
• Varies in thickness, depending on location
• contains of collagenous and elastic fibers.
Significance?
Dermis
• Papillary layer - superficial dermal layer
– Looseness of tissue allows cells to move
around.
• Dermal papillae
– House capillary loops, pain receptors,
Meissner’s corpuscles
– Palms and soles they are arranged in patterns
– Significance?
Dermis
• Reticular layer - deepest skin layer
– Contains: blood vessels, sweat and sebaceous
glands, and Pacinian corpuscles
– Phagocytes also found in this layer
• Collagen and Elastic Fibers
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Found throughout dermis
Binds water to keep skin hydrated
Other roles?
What happens as you age?
Subcutaneous Layer
(hypodermis)
• no distinct boundary between subcutaneous
and dermis
• composed of loose connective and adipose
– If it contains adipose tissue, what is a major
function of the hypodermis?
• contains - major blood vessels
Hair
• Functions of hair?
• hair follicle - group of epidermal cells
inside a dermal sheath
• Functions • nourished by dermal vessels
• Pg 118
• Where do you think cell division happens?
• The hair shaft is completely keratinized.
– How do you think the root differs?
Hair
• Arrector pili muscles attach to the hair follicle.
• What happens when they contract?
• Hair color
– What causes dark vs blonde vs white hair?
– Another pigment, trichosiderin, is found in red hair
Hair
• Hirsutism - excessive hairiness in women
– Results from over production of hormones
caused by an ovarian or adrenal gland tumor
• More testosterone production creates more
terminal hair in women
Sebaceous Gland
• Typically associated with a hair follicle
• secrete sebum, oily mixture, into hair
follicles
• Purpose of sebum?
• These become more active during what
period of life?
Sweat glands
• Consists of a tiny tube originating from a
ball-shaped coil in the deeper dermis
• eccrine glands - most numerous
– function to cool the body
• Sweat consists of water, salts, urea, uric
acid, lactic acid
• Sweat is acidic
– Significance?
Sweat Glands
• appocrine glands - found in genital and axillary
regions
– Secretions are odorless, what causes the odor?
– When do these become active?
– Possible equivalent to sexual sweat glands in other
animals
• Other modified sweat glands are mammary glands
and ceruminous glands (ear)
Nails
• Protective coverings
• What can be said about the keratinization of
epithelial cells in the skin vs. hair vs. nails?
• Cell division happens in the nail matrix
• The lunula is the most active growing
region
• Cells then slide up to the nail bed
• Why do nails have a pinkish color?
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Skin disorders
Jaundice
Bed sores
Acne
Whiteheads
Blackheads
Seborrhea
Blister
Rosacea
Shingles
Striae
Warts
Seborrheic keratoses
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Ringworm
Cyanosis
Athlete’s foot
Boils
Cold sores
Contact dermatitis
Impetigo
Psoriasis
Alopecia
Cysts
Lipoma
Eczma
Vitiligo
Skin Cancer
• Carcinomas - originating in epithelial cells
• What layer?
• Basal Cell Carcinoma
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slow growing
typically removed by surgery
caused by prolonged sun exposure
~80% of skin cancers
Skin Cancer
• melanomas - originating in melanocytes
– Associated with preexisting moles
– can arise from normal skin or a mole
– survival rate is high if removed in horizontal
phase
Melanomas
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ABCD
Asymmetry
Border
Color (several colors)
Diameter (larger than a pencil eraser
Healing Wounds
• Blood vessels break, which causes?
• What part of blood will trigger these
events?
• Cascade of events creates a protein mesh
• How will this help to stop bleeding?
Healing wounds
• What happens to the area around a wound?
• Inflammation
– What cells will trigger this response?
– Vessels dilate and become more permeable
(plasma and leukocytes)
– Benefits of leukocytes?
– Release growth factors
Healing Wounds
• Proliferation
– Fibroblasts migrate to injured region
– What type of tissues do they form? What are
the benefits of this tissue?
– Other cells are responsible for reconstructing
blood vessels, nerves, epidermis
Healing Wounds
• Maturation
– Could take up to a couple years
– The major goal is to increase strength of the
dermis
– What cell would be a primary player?