The CpG PAMP is recognized by the pattern recognition receptor (PRR) Toll-Like Receptor 9 (TLR9), which is constitutively expressed only in B cells and plasmacytoid dendritic cells (pDCs) in humans and other higher primates.
The trachea is an important structure within your respiratory system, which is the organ system that delivers oxygen to your bloodstream. The trachea is a rigid tube that conducts air from your larynx to your bronchi. The trachea's rigidity is maintained by a series of cartilaginous rings arranged along its length called C-shaped cartilage rings.
Lungs are the major organ of our respiratory system, helping us obtain oxygen and get rid of carbon dioxide. Our chest cavity houses a pair of lungs which open to the external environment through the nose and mouth. A cylindrical tube, called trachea, is the main link between the lungs and the nose and mouth. When we breathe in, air travels through the trachea to our lungs. As the trachea moves down the chest, it splits into two branches called bronchus, one for each lung. Each bronchus then further subdivides into several smaller tubes called bronchioles.