Bloodstream macrophages mature tissue Chemotaxis. Changes in temperature and humidity. Skin Layers Structure And Function The brain is the best protected organ in the body. . The cellular components include cells of the immune system and the vascular endothelium. These mechanisms include increasing epidermal thickness DNA repair mechanisms and apoptosis antioxidant enzymes and last but not least skin pigmentation. Protection The outermost layer of your skin the epidermis is the thin tough part of your body that acts like a protective shell. Protects against UV radiation by melanin pigments produced by melanocytes in the epidermis and dermis. Sebum unsaturated fatty acids provides a protective film on the skin and inhibits growth. Melanin pigmentation and the evolution of dark skin is an adaptive protective mechanism against high levels of UVR exposure. The next layer of defence is the lymphatic system situ...