First Digit: Solids. The first digit indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects.s defined in international standard IEC 60529, it classifies the degrees of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water in electrical enclosures.
The mucosa is composed of three components (inner to outer): a non-keratinizing stratified squamous epithelium, a lamina propria and the muscularis muscosa. The submucosa is composed of loose connective tissue, blood vessels, lymphatics, lymphoid follicles, the meissner plexus of nerves and submucosal glands.
Link to: 23.1 The GI tract 9. This layer of the GI tract is composed of areolar connective tissue that binds the mucosa to the muscularis. A) Submucosa B) Lamina propria C) Epithelium D) Serosa E) None of the above Ans: A Link to: 23.1 The GI tract 10. This layer functions by secreting a lubricating fluid. A) Serosa B) Submucosa C) Muscularis D) Mucosa E) MALT Ans: A Link to: 23.6 In the small intestine 11. These are composed of prominent lymphatic nodules that function in the immune response.