Bellringer: What is the largest organ of your body? What

system is it part of? Write your answer down on a fresh sheet of

paper or notetaking device!

• http://www.youtube.com/watch?v=uH_uzjY2bEE

Integumentary System

• Integument- “covering”

• Parts:– Skin– Sweat and oil glands– Hair– Nails

Functions?

Fun Facts

• Skin = 7% of your total body weight

• ~80% of dust in your home is dead skin cells

• More than 500 species of bacteria living on your skin

• 1.5-4 mm thick

3 Main Layers

Epidermis

• Epi = upon• Dermis = skin• Tough but loosely anchored• New cells created deep• Mostly dead– “Beauty is only skin deep” ?!

• 5 layers

4 Important Cells:

• Keratinocytes– Produce protein keratin which gives skin protective

qualities• Melanocytes– Produce melanin (nucleus umbrellas!)

• Langerhans– Phagocytes

• Merkel cells– Sensory cell

Stratum Basale “Basal Layer”

• Deepest• Produces keratinocytes• Mitosis hotspots• Merkel hangout

Stratum Spinosum“Prickly Layer”

• Funny shaped keratinocytes• Langerhan hangout• Tension-resisting

Stratum Granulosum“Granular Layer”

• 3-5 cell layers thick• Waterproofing• Cell death line

Stratum Lucidum“Clear Layer”

• Only in thick skin• Just a few rows of dead keratinocytes

Stratum Corneum“Horny Layer”

• 20-30 dead cells thick• 75% of epithelial thickness• Protects against abrasion and penetration

FULL OF HORNY CELLS(they’re shaped like horns)

Activities!

• Color the different layers of the epithelium

• Draw pictures of each cell type and epithelial layer using a microscope