The Integumentary System

Section 32.3

Functions• Protection• Temperature Regulation• Excretion• Information Gathering• Vitamin D Production

Structure: Skin• Epidermis– Outer layer of skin– Two layers

• Top layer=dead cells• Inner layer=living cells &

stem cells.

– Melanocytes

• Dermis– Contains

• collagen• blood vessels• nerve endings• sensory receptors• hair follicles• smooth muscle• sweat/sebaceous glands

Structure: Hair• Made of keratin• Protects against UV rays, cold temps, and

dirt/pathogens from entering nose/eyes/ears.• Produced in hair follicles

Structure: Nails

• Made of keratin• Grow from nail root– Cells divide and are filled with keratin• This produces a tough, plate-like nail

• Grow at 3mm per month

Skin Problems

• Acne– When sebum/dead cells plug hair follicles– Bacteria trapped in plug– 85% people experience

Skin Problems

• Hives– Red welts, signify an allergic reaction– Histamines released, cause swelling, blood vessel

widening.– Fluid oozes into surrounding tissues.

Skin Problems• Cancer– Excessive exposure to UV radiation.– 60,000 people in USA get it each year, 8000 die.– Protect yourself from both UV-A and UV-B rays!

Skin Cancer

• Basal cell carcinoma• Squamous cell carcinoma• Melanoma