Mucous MembraneTwo to three layers :epitheliumlamina propria (an areolar connective tissue)muscularis muscosae (a layerof smooth muscle).Lines the passages that open to the exterior environment; have absorptive, secretory and protective functions; traps bacteria and foreign particles. Digestive, respiratory, urinary and reproductive tracts.Serous Membrane (serosa) Simple squamous epithelium resting on a thin layer of areolar connective tissueLine the insides of some body cavities and form a smooth outer surface on some of the viscera. The pleurae, pericardium and peritoneum.Serous membranes produce watery serous fluid, which arises from the blood and derives its name from the fact that it’s similar to blood serum in composition.Tunica interna of the blood vessels andendocardium of the heart are membranes made up of a simple squamous epithelium called endothelium. Endothelium rests on a thin layer of areolar tissue, which often rests in turn on an elastic sheet.4. Integumentary System: consists of the skin and its accessory organs-the hair, nails and cutaneous glands. The study of the integumentary system is Dermatology.The skin is the body’s largest and heaviest organ.The skin consists of two layers: epidermis and dermis.Thick skin covers the palms, soles and surfaces of the fingers and toes. Thick skin has a layer of dead cells called the stratum corneum.