Transcript Integumentary Notes

Integumentary Notes
January 7th, 2015
Major Organ:
Skin (largest organ in the body)
Functions:
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Protects the body from injury and infection
Prevents the loss of water (dehydration)
Regulates body temperature
Gathers information about the environment
Produces vitamin D
Eliminates wastes (excretion)
Skin Diagram
Skin Structure: Epidermis
Epidermis: top layer of skin composed of epithelial
tissue (no nerves or blood vessels)
• Uppermost cells of the epidermis are dead and
filled with keratin (protein in fingernails) which
protects the lower layers
• Epidermal cells only live for about 4 weeks
• Pores: holes in the epidermis that lead to sweat
glands
Skin Structure: Epidermis
• Lower cells in the epidermis produce the pigment
melanin (pigment = color molecule)
• Melanin: dark pigment that protects skin cells
from UV radiation in sunlight which can cause
skin cancer
More melanin = darker skin
Less melanin = lighter skin
Skin Structure: Dermis
• Dermis: Lower layer of skin with blood vessels
and nerves (connective tissue); location of the
following:
• Sweat glands: release salt water from the body
which evaporates on the surface of the skin,
cooling the body; also excretes (releases) waste
chemicals
• Oil glands: found near hair follicles the oil
waterproofs the hair and moistens the skin
Skin Structure: Dermis
Hair follicle: structure from which hair grows
Hair: sense insects, keeps body warm (not humans),
top part is made of dead cells
• Some cells in the dermis also produce Vitamin D
when sunlight hits them
• Vitamin D: regulates calcium uptake in the body,
leads to strong bones