Each of these substances is produced by exocrine or endocrine cells found in the mucosa. 1  The main exocrine product of the stomach is gastric juice â a mixture of mucus, hydrochloric acid, and digestive enzymes. 2  Gastric juice is mixed with food in the stomach to promote digestion.
Industry is the production of goods or related services within an economy. The major source of revenue of a group or company is the indicator of its relevant industry. When a large group has multiple sources of revenue generation, it is considered to be working in different industries.
The airline industry became a systems-oriented world. Actually, the industry is a complex system defined by the interactions among its several sub-systems: aircrafts, airports, passengers and aviation policy. It is also a complex system in the sense that it encompasses several simpler sub-systems.