Upper Respiratory Tract Infection (URTI)
Updated: Oct 29, 2021
The upper respiratory tract consists of sinuses, nasal passages, pharynx, and larynx. These structures direct the air we breathe from the outside to the trachea and eventually to the lungs for respiration to take place.
The potential complications of upper respiratory tract infection are Otitis media, Bronchitis,
Bronchiolitis, Pneumonia and several other diseases. The rhinovirus is the most common viral infectious agent. It is one of the chief cause of common cold, which is most common URTI.
(Isosurface of the capsid of human rhinovirus 14, one of the viruses which cause the common cold. Protein spikes are colored white for visual clarity. Note the icosahedral symmetry. Based on Protein Data Bank entry 4RHV. Rendered in Maxon Cinema 4D, Thomas Splettstoesser)
Upper respiratory infection, is an infectious process of any of the components of the upper airway.
Infection of the specific areas of the upper respiratory tract can be named specifically.
The URTI is generally caused by the direct invasion of the inner lining (mucosa or mucus membrane) of the upper airway by the culprit virus or bacteria. In order for the pathogens (viruses and bacteria) to invade the mucus membrane of the upper airways, they have to fight through several physical and immunologic barriers.
The hair in the lining of the nose acts as a physical barrier and can potentially trap the invading organisms. Additionally, the wet mucus inside the nasal cavity can engulf the viruses and bacteria that enter the upper airways. There are also small hair-like structures (cilia) that line the trachea which constantly moves any foreign invaders up towards the pharynx to be eventually swallowed into the digestive tract and into the stomach.
In addition to these intense physical barriers in the upper respiratory tract, the immune system also does its part to fight the invasion of the pathogens or microbes entering the upper airway. Adenoids and tonsils located in the upper respiratory tract are a part of the immune system that helps fight infections. Through the actions of the specialized cells,