Skin, Hair and Nails: Lesson BWHS

Skin, Hair and Nails

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What is the integumentary system?

​Skin

• ​Weighs about 15% of your body weight

• ​largest organ of your body

• ​3 million sweat glands

• ​About 2 DVDs thick on average

• ​Thicker on the soles of your foot

• ​Thinnest on your eyelids

​Epidermis

• ​top layer of skin is called epidermis- epi means above/on top

• ​20-50 layers of flat, DEAD cells

• ​as thick as a piece of a paper

• ​completely shed every 3-4 weeks

• ​and yes, makes up dust found in the air

Random

• ​Pain receptors found in both layers of skin

• freckles are clumps of melanin​

• ​1 square inch of skin contains: 10 hairs, 15 sebaceous glands, 100 sweat glands, 3 feet of tiny blood vessels

​Hair & Nails

• ​Hair grows 1mm every 3 days

• ​100 hairs are lost a day

• ​Hair is made of same material as animal horns/ bird feathers

• ​Fingernails grow 3mm month but toenails grow a lot slower

• ​Small white crescent at base of your nail is called lunula since it looks like a moon

• ​Function of nails is to protect your fingers/toes