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.
Composed of orderly arrangement of connective tissue and contractile cells. Entire muscle is surrounded by connective tissue wrapping, Epimysium. Skeletal Muscle is made of Fasicles, which are bundles of individual muscle cells, which are each surrounded by a connective tissue layer called Perimysium. Internal Structure of Skeletal Muscle. A bundle of muscle cells (fibers) bound together by connective tissue to form a functional unit.