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