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Bellwork

Bellwork. Do you think the skin is an organ? Explain your answer. Bellwork. YES! An organ is a group of tissues working together for a specific function, therefor skin is an organ. The skin and it’s various accessory structures make up the……. Integumentary System. Chapter 4. Functions.

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Bellwork

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  1. Bellwork • Do you think the skin is an organ? Explain your answer.

  2. Bellwork • YES! An organ is a group of tissues working together for a specific function, therefor skin is an organ. • The skin and it’s various accessory structures make up the……

  3. Integumentary System Chapter 4

  4. Functions • Prevents harmful substances from entering body • Bacteria, UV radiation, chemicals • Prevents too much water loss • Regulates body temperature • Produces vitamin D

  5. Skin and it’s tissues • Two distinct layers: • Cutaneous: (THIS IS YOUR SKIN) • Epidermis (outer): stratified squamous epithelial tissue • Dermis: (inner): connective tissue, smooth muscle, nervous tissue • Subcutaneous: (THIS IS BELOW YOUR SKIN) • Areolar and adipose tissue • Contains major blood vessels to supply the skin

  6. Questions • 1. What kind of tissue is the outer layer of skin made of? • 2. What kind of tissues is the inner layer of skin made of?

  7. Epidermis

  8. Epidermis • Stratum corneum: dead keratinized cells • Stratum lucidum: only present in palms and soles of feet • Stratum granulosum: cells die • Stratum spinosum: keratin fibers accumulate • Stratum basale: cells divide and grow

  9. Question • Explain how the epidermis is formed.

  10. Epidermis • Melanocytes: cells that produce the dark pigment melanin • Melanin absorbs UV radiation which would otherwise cause mutations in DNA

  11. Poll • Do you think African Americans have more melanocytes than Caucasions? • Answer: They all have the SAME! The difference in color of skin has to do with the amount of melanin those cells produce.

  12. Epidermis • Sunlight and tanning beds stimulate melanocytes to produce more melanin and we get darker! • Other factors in color of skin: • Blood oxygen levels • Blood vessel dilation (when embarassed, overheated, or intoxicated you get red; when cold or afraid you get pale)

  13. Questions • 1. What is the function of melanin • 2. How do physiological factors influence skin color?

  14. Dermis • Papillary layer – areolar connective tissue • Reticular layer – dense irregular connective tissue Can be as thin as 0.5 mm on the eyelids or as thick as 3 mm on the bottom of feet!

  15. Dermis • Also contains muscle fibers and dendrites (part of the neuron that picks up signal) • Accessory structures: • Blood vessels, hair follicles, sebaceous glands, sweat glands

  16. Exit Ticket • Given what you learned today about the epidermis and the dermis, where do you think the ink in a tattoo lies? Explain your answer.

  17. http://media.pearsoncmg.com/bc/bc_marieb_happlace_7/labeling/fig_0501.htmlhttp://media.pearsoncmg.com/bc/bc_marieb_happlace_7/labeling/fig_0501.html

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