Final answer:
The pharyngeal tonsils, also known as adenoids, are located near the posterior opening of the nasal cavity on the roof of the nasopharynx and play a crucial role in the body's immune response by trapping and destroying pathogens.
Step-by-step explanation:
The tonsils located near the posterior opening of the nasal cavity are called the pharyngeal tonsils. These are also commonly known as adenoids when they become swollen. The pharyngeal tonsil is an aggregate of lymphoid reticular tissue, similar to a lymph node, found in the superior portion of the nasopharynx. They play a crucial role in the immune system by trapping and destroying invading pathogens that are inhaled. It is interesting to note that the pharyngeal tonsils are more prominent in children and tend to regress and possibly even disappear with age.
The pharyngeal tonsil contains a rich supply of lymphocytes and is covered with a ciliated epithelium that is adept at capturing and eliminating pathogens from the air you breathe. The tonsils in general, including the palatine and lingual tonsils located in the oropharynx, are critical for developing immunity to oral pathogens and trapping pathogens entering through the mouth or nose.