"Brounchus" appears to be a misspelling or miscommunication, as it does not correspond to any widely recognized term in English. If you meant "bronchus," it refers to the major air passages that branch from the trachea into the lungs. The bronchus plays a crucial role in the respiratory system by allowing air to enter and exit the lungs. If you were referring to something else, please provide more context.
The original source of oxygen in the alveoli is inhaled air that enters the lungs during the process of breathing. Oxygen is extracted from the air in the alveoli and then diffuses into the bloodstream to be circulated to the body's tissues. This process is essential for cellular respiration and energy production.
They are found scattered among the epithelial lining of organs, like the intestinal and respiratory tract. They are also found in the trachea, brounchus. They are also in the respiratory tract, small intestines, the colon, and conjunctiva in the upper eyelid .This information was all found on wikipedia so i cannot take all of the credit for this.