Integumentary system
Sept 24-25 2015
What do you already know about the integumentary system?
Integumentary System
Components:› Skin (aka cutaneous membrane or
integument)› Hair› Nails
Integumentary System
Components:› Skin (aka cutaneous membrane or
integument)› Hair› NailsFun fact:The skin is the largest organ in the body.
The skin of an average adult weighs more than 9 lbs!
Integumentary System
Functions1. Protection 2. Thermoregulation 3. Excretion of wastes4. Synthesis of vitamin D
Functions of Integumentary System
1. Protection › From mechanical and chemical damage
Barrier of tough, keratinized cells Pain receptors warn body of possible damage
› From pathogens Unbroken surface Acidic secretions inhibit bacterial growth Phagocytes ingest foreign material
› From UV radiation Melanin absorbs UV light and prevents it from
reaching deeper layers
Functions of Integumentary System
1. Protection › From thermal damage
Pain receptors warn body of possible damage› From desiccation (drying out)
Keratin and other substances keep skin fairly waterproof
Functions of Integumentary System
2. Thermoregulation How does the skin help us cool down?
How does the skin help us warm up?
Functions of Integumentary System
2. Thermoregulation How does the skin help us cool down?
› Evaporative cooling (sweating)› Increased blood flow through skin (increases
heat loss)
How does the skin help us warm up?› Goose bumps: arrector pili muscles contract to
pull hair upright, and add insulation to body› Decreased blood flow through skin (reduces heat
loss)
Functions of Integumentary System
3. Excretion of wastes – › The sweat glands excrete metabolic wastes
(urea, uric acid), salt, and lactic acid (in addition to water)
4. Synthesis of vitamin D› When UV light hits the skin,
modified cholesterol molecules are converted into vitamin D.
Quick ReviewTurn & Talk (5 min), then share with class.
Scholar on left … Name the four major functions of the integumentary
system. Explain how the skin fights pathogens.
Scholar on the right … Name the three components of the integumentary
system. Explain how the skin allows us to thermoregulate.
Skin StructureThe skin is composed of two layers:
1) Epidermis – made of _______________ tissue
2) Dermis- made of _______________ tissue
Skin StructureThe skin is composed of two layers:
1) Epidermis – made of epithelial tissue
2) Dermis- made of dense connective tissue
Skin Structure
Fun fact:Blisters occur when friction causes the epidermis to pull away from the dermis.
Epidermis StructureEpidermis is made of epithelial tissue.
Quick Review:What are the characteristics of epithelial tissue?
Epidermis StructureEpidermis is made of epithelial tissue.
Quick Review:What are the characteristics of epithelial tissue? Form continuous sheets, have cell junctions Avascular Apical side free Other side attached to basement membrane Regeneration
Remembering these characteristics will help you understand the structure and function of the epidermis!
Epidermis StrataThe epidermis has multiple strata or layers.
Only the deepest layer contains actively dividing cells and melanocytes.
Why?Because the deepest layer is closest to the blood supply.
As new cells form, older cells are pushed towards the surface
Epidermis StrataAs the cells are pushed away from the blood supply, they atrophy and flatten.
The most superficial layer is made of the dry, keratinized membranes of skin cells.
Epidermis CellsTwo main cell types in epidermis:1) Keratinocytes
› Keratin-producing cells› Keratin is the protein that makes skin tough and waterproof.› Most abundant cell in epidermis
2) Melanocytes› Melanin-producing cells› Melanin is the brown-black pigment that is largely
responsible for skin, hair, and eye color› Melanin absorbs UV light to product DNA from damage› Found only in deepest layer of epidermis
JFF: Skin Color Major determinants of skin color
› Amount / type melanin› Amount carotene (from fruits and veggies)› Amount oxygen in blood
Adaptive significance› Trade off between UV protection and vitamin D
production
Dermis The dermis is made of what tissue?
Dermis The dermis is made of what tissue? Connective
(specifically, dense irregular)
Connective tissue cushions and binds things together. In the skin, the connective tissue holds together lots of different elements:• Exocrine glands• Hair follicles• Nerves and sense receptors• Blood vessels
The collagen and elastic fibers of the dermis give skin its strength and elasticity
Diseases & Disorders: Burns
First degree burn: only epidermis is damaged.
Second degree burn:Damage extends partway into dermis.
Third degree burn:Damage extends all the way through dermis.
Diseases & Disorders: Burns
First degree burn: only epidermis is damaged.
Second degree burn:Damage extends partway into dermis.
Third degree burn:Damage extends all the way through dermis.
Signs: red, swollen skinExample: most sun burnsWill heal on own
First degree burn: only epidermis is damaged.
Second degree burn:Damage extends partway into dermis.
Third degree burn:Damage extends all the way through dermis.
Signs: red, swollen skinExample: most sun burnsWill heal on own
Signs: blisteringSkin will heal with care
Diseases & Disorders: Burns
First degree burn: only epidermis is damaged.
Second degree burn:Damage extends partway into dermis.
Third degree burn:Damage extends all the way through dermis.
Signs: red, swollen skinExample: most sun burnsWill heal on own
Signs: blisteringSkin will heal with care
Signs: blackened or blanched (gray-white) skin, lack of pain due to damaged nervesSkin will not heal; grafts must be done
Diseases & Disorders: Burns
Burned skin can no longer carry out its functions
Turn & TalkQuick review: What are the functions of the skin? Analyze: Which functions are most critical?
How do burns disrupt homeostasis?
1)Protection from abrasion / chemical damage / UV damage / pathogens / against dessication
2)Excretion of wastes3)Thermoregulation4)Synthesis of Vitamin D
Burned skin can no longer carry out its functions
Most critically, skin can no longer› Prevent loss of fluids and electrolytes
Fluid loss and electrolyte imbalance can cause kidneys to shut down and patients to go into shock due to low blood volume.
Happens almost immediately, unless fluids are replaced.
› Protect the body from pathogens Infection becomes a major concern within 2-3 days
following severe burns.
How do burns disrupt homeostasis?
Burned skin cannot thermoregulate. Hypothermia becomes a problem.
3rd degree burns cannot regenerate. Scar tissue forms. Scar tissue does a poor job of perfoming the functions of skin, and if the scar tissue is extensive, mobility may be affected.
Other complications of burns
Exit Ticket
In a short paragraph explain how burn classification and severity is related to the structure and function of the skin.