Unit 2 Skin Functions Flashcards
What are the functions of the skin?
- Protection
- Touch
- Temperature Control
- Healing Wounds
What are two ways the skin protects us?
- Epidermis provides a waterproof barrier to which keeps out microorganisms such as bacteria and fungi.
- Melanin protects us from UV radiation in sunlight
What 3 things can sensory nerves in the skin detect?
- Pressure
- Temperature change
- Pain
How does the skin aid in Vitamin D production?
Some skin cells produce a Vitamin D precursor (dehydrocholesterol) , which when exposed to sunlight creates an inactive form of Vitamin D (cholecalciferol).
In the liver and kidneys the inactive form is modifed and becomes active active Vitamin D (calcitriol).
How does the skin help with temperature regulation?
When the body temperature is above the set point, the nervous system tells structures in the skin and other organs to release heat.
When the body temperature is below the set point, the brain triggers different responses to the skin structures.
Explain how the body cools itself during physical exercise.
- Active muscles release heat, which is carried awy in the blood.
- The warm blood reaches the hypothalmus (in the brain) which controls the body’s temperature set point.
- Smooth muscle in the dermal blood vessels are signaled to relax and dilate (vasodilation)
More blood enters them
Some heat is released to,lower body temperature - The merocrine glands also become active to release sweat onto the skin surface
As liquid evaporates it carries heat away from the surface, cooling the skin
Explain how the body warms itself in a cold environment.
- The smooth muscle in the walls of the dermal blood vessels are stimulated to contract
Decreasing the flow of heat-carrying blood through the skin
Helps reduce heat loss - Merocrine sweat glands remain inactive, decreasing heat loss by evaporation
- Skeletal muscles can be stimulated throughout the body to contract slightly which i creases the rate of cellular respiration that releases heat
- Small groups of muscles may rhythmically contract with greater force, which causes the person to shiver, generating more heat
What is hypothermia?
When the body temperature falls below 95 degress.
What are the initial symptoms of hypothermia?
Shivering
Feeling of coldness
What are the symptoms of worsening hypothermia?
- Loss of coordination
- Stiffening muscles
- Confusion
- Fatigue
- Slow, shallow breathing
What is hyperthermia?
Core body temperature above 101 degrees
What are the initial symptoms of hyperthermia?
Skin becomes hot, dry and flushed
What are the symptoms of worsening hyperthermia?
- Weakness
- Dizziness
- Headaches
- Rapid, irregular pulse
How does the skin respond to a shallow wound?
Epithelial cells along the wound margin are stimulated to divide more rapidly.
Newly formed cells fill the gap of the wound
What is a deep wound?
A wound that extends into the dermis or subcutaneous layer.
How does the skin respond to a deep wound?
- Blood vessels break and the released blood forms a clot in the wound
- The blood clot and and dried tissue fluids form a scab that covers and protects underlying tissues
- Fibroblasts migrate into the area and begin secreting collagen fibers that bind the edges of the wound
- Suturing (stitches) or otherwise closing a large break in the skin speeds this process
What are the three stages of wound healing?
- Inflammatory
- Proliferation
- Remodeling
What happens during the inflammatory stage of wound healing?
- The skin around the wound may become inflamed, reddened, swollen, painful and warm to the touch.
- Blood vessels in affected tissue dilate and provide tissues with more nutrients and oxygen to aid healing.
What happens during proliferation stage of wound healing?
- Blood vessels extend into areas beneath the scab
- Phagocytic cells remove dead cells and other debris
- Eventually, the damaged tissues are replaced, and the scab sheds off
What causes a scar?
Extensive production of collagen fibers may form an elevation above normal epidermal surface during wound healing.
What causes skin to appear red after getting a sunburn?
Dermal blood vessels dilate
What is a first degree (partial thickness) burn?
Any burn to only the epidermis
What is a second degree (deep partial thickness) burn?
A burn that destroys some epidermis and some underlying dermis
What is a third degree (full thickness) burn?
A burn that destroys the epidermis, dermis and accessory structures of the skin
How do second degree burns heal?
- Fluid escapes from the damaged dermal capillaries, accumulating beneath the outer layer of the epidermal cells, forming blisters.
- Stem cells divide and their daughter cells grow out onto the surface of the exposed dermis, spread over it and become the new epidermis
Describe the appearance of the skin after a second degree burn?
The skin becomes moist and firm and color varies from dark red to waxy white
How do third degree burns heal?
Epithelial cells from the margin of the wound grow inward.
A skin graft can speed up this process.
Describe the appearance of the skin after a third degree burn.
Skin becomes dry and leathery and may vary in color from black to white
What is a skin graft?
A collagen framework seeded with the patient’s own skin cells that provides a skin substitute for transplant.
What is the rule of nines?
- An aid for estimating the extent of damage burns cause.
- The body is divided into regions, each representing 9% (or multiple of 9%) of the total skin surface area.
In the rule of nines, the trunk counts for what percentage?
36%
In the rule of nines, the arms count for what percentage?
Each arm is 9%
In the rule of nines, the legs count for what percentage?
Each leg counts for 18%
In the rule of nines, the head counts for what percentage?
9%
In the rule of nines, the genetalia counts for what percentage?
1%
