UN Thread Types. UN (Unified) is a specification of the shape and dimensions of the thread for a given size (diameter) of fastener and number of threads per inch of fastener length. UN bolts and machine screws are the type of fastener in everyday use in the US, UK, and Canada. UN, UNR, and UNJ thread dimensions are measured in Imperial units.
Causes The airway can become narrowed or blocked due to many causes, including: Allergic reactions in which the trachea or throat swell closed, including allergic reactions to a bee sting, peanuts, antibiotics (such as penicillin), and blood pressure medicines (such as ACE inhibitors) Chemical burns and reactions. Epiglottitis (infection of the structure separating the trachea from the esophagus)
Sometimes you may swallow and cough because something âwent down the wrong pipe.â The body has two âpipesâ â the trachea (windpipe), which connects the throat to the lungs; and the esophagus, which connects the throat to the stomach. Trachea and esophagus conditions include swallowing disorders and Zenkerâs diverticulum, which occurs when the muscles at the back of the throat become weak and stretched out, forming a pouch.