Integumentary system

Sept 24-25 2015

How do I keep my body healthy?

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.